Chemistry Perfect Score Module Form 4 2011 No Logo
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Form 4 Score A+ Module
CHEMISTRY SCORE A+ MODULE FORM 4
SET 1
1. The Structure of Atom 2. Chemical Formulae and Equations
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Form 4 Score A+ Module
STRUCTURE OF THE ATOMS 1.
Matter is anything that …………………………………………………. and has ……………………. …………………….
2.
The particle theory of matter state that matter is ……………………………..…………………………
3.
Type of particle Example
4. Property Diagrammatic representation of the particles part icles in each of the physical states Arrangement of particles.
Solid
Liquid
Gas
Forces of attraction between particles Movement of particles Energy content
5.
Subatomic particles in an atom. Subatomic particle
6.
Symbol
Isotope are atoms with the same
Relative mass
Charge
………………………………………………… but different
…………………………………………………………………………………. 7.
The isotopes of an element have same ………………………………………….….. but different ………………………………… because they have ….………………………………………………
8.
Compare and contrast the atoms below. 12
14
C
C
6
6
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Form 4 Score A+ Module
9.
Complete the table below.
Isotope Carbon-14
Uses
Cobalt-60
Sodium-24
PAPER 2 : STRUCTURE 1. (a)
Diagram Diagra m 1.1 shows the results of an experiment experiment to investigat e the movement of bromine particles part icles in air.
Air
Gar jar Cover
Bromine vapour
Diagram 1.1
Reddish brown vapour spreads throughout throughout both gas jars within 10 minutes
Cover removed
(i)
State the name of the process involved in this experiment.
(ii)
………………………………………………………………………………………...…...……… [1 mark] State the type of particles present in bromine gas. ………………………………………………………………………………………….....……… [1 mark]
(iii)
Explain the observation in this experiment based on the kinetic theory of matter. ……………………………………………………………………………………….…...……… ……………………………………………………………………………………….…...……… ……………………………………………………………………………………….…...……… [3 marks]
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Form 4 Score A+ Module
Temperature
83 Diagram 1.2
R
T
Time, s (b)
Diagram 1.2 shows a graph gra ph of temperature against time when solid X is heated? (i) State the melting point of X. ………………………………………………………………………………...………………… [1 mark] What happens to the temperature while the substance c hanges state? Explain.
(ii)
……………………………….…………………………………………………...…………..…… …………………………………………………………………………………...…………...…… …………………………………………………...………………………………………...……… [2 marks] (iii)
Explain the movement of particles X between R and T during heating. ……………………………………………………………………………………………...……… ……………………………………………………………………………………………...……… [2 marks]
Glass wool soaked in concentrated hydrochloric acid
Glass wool soaked in concentrated ammonia solution
Diagram 2 2.
Diagram 2 shows the set-up of apparatus appara tus to investigate the reaction between concentrated hydrochloric acid and concentrated ammonia solution to form substance X. Based on the information, answer the following questions. (a)
(i)
What is the observation observati on in the glass tube? ……………………………………………………………………………………...……… [1 mark]
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Form 4 Score A+ Module
(ii)
Name substance X ……………………………..……………………………………………………………...……… [1 mark]
(iii)
Name the process occurs in the glass tube. …..………………………………………………………………………………………...……… [1 mark]
(b)
Which gas diffused faster? Why? …………………………..…………………………………………………………………...…….…… ………….…….………………………………………………………………………………...………. [2 marks]
(c)
Write the chemical equation for the reaction in the experiment. ……………………..…………………………………………………………………………...……… [1 mark]
3.
Table 3 shows proton number and nucleon number for atom W, X and Y. Atom
Proton number
Nucleon number
W
11
23
X
17
35
Y
17
37
Table 3
(a)
(b)
(i)
What is meant by proton number?
(ii)
.....................................................................................………………………………............... [1 mark] What is the number of neutron in atom W ?
......................................................................………………………………………................ [1 mark] Which atoms are isotopes? Explain why. ............................................................................................................................................................
(c)
........................................................................................................................................................... [2 marks] Write the electron electr on arrangement arra ngement of atom a tom X . .......................... ................................................................................................................................... [1mark]
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Form 4 Score A+ Module
(d)
(i)
Draw the electron arrangement of atom Y. In your diagram , show the number of proton and the number of neutron in the nucleus.
[2 marks] (ii)
What is the number of valence electron electro n of atom Y?
(iii)
..................................................................................................................................................... [1 mark] Write the formula of ion Y. ..................................................................................................................................................... [1 mark]
(e)
Write the symbol of atom X in the form of
A Z
X.
.............................................................................................................................................................. [1 mark] 4.
(a)
Diagram Diagra m 4.1 shows the set-up of an experiment to determine determi ne the melting point of solid X.
Thermometer
Water
Diagram 4.1
The temperature of X is recorded at 30 seconds intervals as shown below.
Time/second
0
30
60
90
120
150
180
210
70
77
80
80
80
82
85
95
o
Temperature/ C
(i)
Plot the graph of temperature against time for the heating of X on the graph paper. [3 marks]
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Form 4 Score A+ Module
Graph temperature against time
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Form 4 Score A+ Module
(ii)
On the graph that you have drawn in (a), label the melting point of substance
X.
[1 mark] (iii)
Explain why the temperature tempera ture remains constant from 60 s to 120 s? …………….……......................................................................................................................
(iv)
………….................................................................................................................................. [2 marks] o Draw the arrangement arra ngement of particles part icles in X at 85 C
[ 1 mark ] (b)
(c)
Why has the solid X in the boiling tube be stirred constantly consta ntly with the thermomet er during the experiment? …………………………….................................................................................................................... [1 mark] Why solid X is not directly heated without using water bath? …………..………………..................................................................................................................... [1 mark]
5.
Table 5 shows four substances and their respective formulae. Substance
Chemical formula
Iodine Copper Ethanol Potassium chloride
I2 Cu C2H5OH KCl Table 5
(a)
State 2 substances substanc es that consist of molecules.
(b)
……………………………..................................................................................................................... [2 marks] Which of the following substances substa nces has a highest melting point?
(c)
……………………............................................................................................................................... [1 mark] State the substance that can conduct electricity in the solid state.
(d)
……………………............................................................................................................................... [1 mark] Name the particles part icles present in potassium potass ium chloride. ……………………............................................................................................................................... [1 mark]
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Form 4 Score A+ Module
PAPER 2 : ESSAY 6.
Diagram 6.1 shows an atom of an element based on the model by James Chadwick.
Electron Proton Neutron Diagram 6.1 (a)
Compare the relative mass and the charge of two of the subatomic subatomic particles in diagram 6.1. [4 marks]
7p 7n
Diagram 6.2 Diagram 6.2 shows an atom of element X. (b) (i) Describe Describ e fully the atomic structure struc ture shown in diagram 7.2. [4 marks] (ii)
Write a symbol for the element in the form of
A Z
(c)
X
[2 marks]
Graph 6.3 shows the heating curve of element Y. o
Temperature / C
Melting point
Graph 6.3 to
t1
t2
t3
Time, minutes
Describe the graph in term ter m of states of matter, particles arrangeme arra ngements nts and changes in energy. [10 marks]
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Form 4 Score A+ Module
7
(a)
What is meant by “melting point”? During the melting of naphthalene, the temperature remains constant even though heat is applied. Explain why. [4 marks] Condensation is the process where a gas changes to its liquid state at a certain temperature and pressure when it is cooled.
(b)
Describe the change of the kinetic energy, arrangement and the forces of attraction between the particles at the following states: (i) (ii) (iii)
Before condensation During condensation After condensation [10 marks]
(c)
3+
Diagram 7 shows the electron arrangement of ion Y . e e
3+
e e e
14 n
n e
e e
neutron electron
e e e
Diagram 7
(i) Calculate the nucleon number of atom Y.
[2 marks]
(ii) Y reacts with oxygen to form oxide Y, with the formula Y2O3. The chemical equation for reaction Y with oxygen is show as: 4Y + 3O2 2Y2O3. Given that the relative atomic mass of Y = 27 and O = 16. Calculate the mass of oxide Y, Y2O3 formed when 10.8 g Y is completely burnt in oxygen. [4 marks] PAPER 3 : STRUCTURE Gas jar cover
Jelly Water
Gas jar Potassium manganate(VII)
Bromine vapour
A
B
Diagram 8
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C
Form 4 Score A+ Module
8.
A group of of students students set up the apparatus for an experiment experiment as shown in diagram 8. The result is is obtained obtained by the students are shown in table 8. Experiment A B C (a)
Observation After a few minutes the gar jar was filled with a reddish brown gas. After a few hours, the water turns purple. After a few days, the jelly turns purple.
State the aim of the experiments carried carr ied out. ……………………................................................................................................................................
(b)
State the hypothesis of the experiments. experiments . ……………………............................................................................................................................... ……………………...............................................................................................................................
(c)
State (i) The manipulated variable. variab le.
(ii)
……………………..................................................................................................................... The responding respond ing variable. …………………….....................................................................................................................
(iii)
The fixed variable of the experiments. experiments. …………………….....................................................................................................................
(d)
(e)
Based on the observat observation, ion, arrange the three states of mater mater in a sequence to show their speed in increasing order. …………………….............................................................................................................................. Based on the the rate of the movement movement of of the particles, describe describe the arrangement of of the particles in the three states of matter. …………………….............................................................................................................................. …………………….............................................................................................................................. ……………………..............................................................................................................................
(f)
Give the daily application applicati on of the process proc ess in one of the above experiment experiment.. ……………………..............................................................................................................................
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Form 4 Score A+ Module
CHEMICAL FORMULA AND EQUATION
1.
Write the chemical formula of the compound in the table below. Ion Sodium
Chloride
Nitrate
Hydroxide
Sulphate
Carbonate
oxide
Magnesium Lead(II) Copper (II) Iron (II) Iron (III) Aluminium 2.
Write balanced chemical equation for the following chemical r eactions. (a) Heat solid of copper (II) carbonate
(b)
…………………………………………………………………………………………. Nitric acid reacts with sodium hydroxide
(c)
…………………………………………………………………………………………. Hydrochloric acid reacts with zinc metal
(d)
…………………………………………………………………………………………. Copper(II)nitrate reacts with magnesium
(e)
…………………………………………………………………………………………. Chlorine gas reacts with lithium hydroxide
(f)
…………………………………………………………………………………………. Hydrogen gas reacts with lead(II) oxide ………………………………………………………………………………………….
3.
Avogadro constant, N A is defined as the number of particles in one mole of a substance [1 Mol any substance consist of 6.02 X 10 23 particles]. Calculate the number of particles in: (a) 0.1 mol of calcium
(b)
1.5 mol of iron
(c)
2.0 mol of oxygen gas
(d)
1.5 mol of helium
(e)
2.0 mol hydrogen chloride
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Form 4 Score A+ Module
4.
5.
Calculate the number of moles of the following f ollowing substances. 23 (a) 6.0 x 10 aluminium
(b)
1.8 x 1021 argon
(c)
1.2 x 1023 bromine gas
(d)
2.4 x 10 carbon dioxide
(e)
3.0 x 1023 ammonia
20
Calculate the mass of following substances.
a) 1.5 mol of chlorine gas
b) 2.5 moles of oxygen gas
c) 2.0 moles moles of sulphuric acid
d) 0.5 moles of ammonia, NH3
e) 2.5 moles moles of lead (II) carbonate
f) 0.5 moles copper(II) nitrate, Cu(NO3)2
Molar volume: The volume of one mole of the gas 3 -1 [22.4 dm mol at STP, standard temperature and pressure] [24 dm3 mol-1 at Room condition] 6.
Calculate the volume of gases below. (a)
0.5 mol of chlorine at STP.
(b)
0.2 mol of carbon dioxide at Room condition.
(c)
1.5 mol of methane at room condition.
(d)
0.5 mol of helium at room condition.
(e)
2.5 mol of ammonia at STP
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Form 4 Score A+ Module
7.
Calculate the number of moles of the gases below. 3 (a) 250 cm of carbon dioxide in room temperatur e.
(b) 500 cm3 of hydrogen sulfide at STP.
3
(c) 200 cm of hydrogen chloride in room temperature.
(d) 750 cm3 of neon in room t emperature.
(e) 300 cm3of ammonia at STP.
8.
Magnesium powder reacts with hydrochloric acid to produce salt and hydrogen gas. (a) Write the balance chemical equation for this reaction.
(b)
…………………………………………………………………………………………. If 2.4 g of magnesium powder is added into excess hydrochloric acid, calculate, (i) The mass of salt formed.
(ii) The volume of hydrogen gas liberated at room temperature.
9.
Lead is extracted according to the following equation. C
+
PbO
CO2
+
Pb
(a)
Write the balanced chemical equation for the reaction.
(b)
Determine the number of moles of lead extracted from 0.5 mole of lead (II) oxide.
(c)
Calculate the number of moles of carbon required to extracts 0.5 mole of lead(II) oxide.
(d)
What is the mass of lead are produced if 44.6 g of lead (II) oxide is heated with excess carbon. [ RAM : Pb = 207, O = 16, C = 12 ]
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Form 4 Score A+ Module
10.
Excess sodium carbonates is added into 50 cm 3 of 0.5 mol dm-3 copper(II) chloride. The chemical equation for for the reaction is is as follows: CuCl2 +
11.
Na2CO3
NaCl
+
(a)
Balance the chemical equation for the reaction.
(b)
Calculate the mass of copper(II)carbonate c opper(II)carbonate..
CuCO3
5g of calcium carbonate is added to excess hydrochloric acid. (a) Write balanced chemical equation for the r eaction. ……………………………………………………………………………………….……. (b) Determine the volume of carbon dioxide gas evolved at room temperature
12.
When sodium bicarbonate is heated, it decomposed to sodium carbonate, carbon dioxide and water. (a) Write a balanced chemical equation for the decomposition of sodium bicarbonate on heating. ……………………………………………………………………………………………..…. (b) If 8.4 g of sodium bicarbonate decomposes, calculate (i) The volume of carbon dioxide gas evolved at room temperature.
(ii) The mass of sodium carbonate formed. f ormed.
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Form 4 Score A+ Module
Concentration of acids and alkalis (STOICHEIOMETRY)
The concentration of a solution is the mass (in gram) or the number of mole of solute dissolved in a solvent 3 to form 1.00 dm of solution. Concentration, g dm-3
Mass of solute, g Volume of solution , dm 3 Number of mole of solute, mol Volume of solution , dm3
-3
Concentration, mol dm / molarity
Titration Formula
Ma Va a
= Concentration of the acid, = Volume of used acid, = the number of mole of acid,
MaV2 =
a
MbVb
b
Mb Vb b
= Concentration of the alkali = Volume of used alkali = the number of mole of alkali
Dilution M1V1 = M2V2 3
-3
13.
100cm of HCl 2.0 mol dm reacts completely with excessive zinc powder. C alculate the volume of gas released at room temperature? (Molar volume = 24 dm 3 at room temperature).
14.
5 g of Calcium Calciu m carbonates carb onates dissolves in 100 cm3 of nitric acid 0.5 mol dm-3 to produce salt, carbon dioxide gas and water. (i) Write out the equation. ………………………………………………………………………………………..…… (ii) Calculate the moles moles of calcium carbonates used. used. (RAM Ca =40, C = 12, O = 16).
(iii) Calculate the moles of acid.
(iv) Calculate the volume of gas produced.
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Form 4 Score A+ Module
15.
X g sodium carbonate reacts completely with 100 cm3 hydrochloric acid -3 1.0 moldm to produce sodium chloride, carbon dioxide and water. Find X. (relative atomic mass: Na =23, C = 12, O = 16)
16.
10 g of copper(II) oxide oxide reacts react s completely completel y with 100 cm hydrochloric hydrochloric acid to form copper(II) chloride and water. Calculate the molarity of acid used. (JAR Cu =64, =64, O = 16 )
17.
The concentration of sodium hydroxide solution is 8.0 g dm -3. (a) What is the molarity of the solution?
3
(b) What is the molarity of the solution produced when 100 cm 3 of distilled water is added to 50 cm 3 of this solution?
18.
In the titration experiment, 25.0 cm3 of 2.0 mol dm-3 sodium hydroxide solution is titrated titra ted with sulphuric 3 acid from a burette. 18.50 cm of sulphuric acid is needed for complete neutralization. neutralization. (a) Write a balanced chemical equation for the neutralization. ………………………………………………………………………………………………… (b) Calculate the number of mole of sodium hydroxide used in this experiment.
(c) Calculate the number of moles of sulfphuric acid needed to exactly neutralize 25.0 cm 3 of 2.0 mol dm3 sodium hydroxide.
(d) Calculate the molarity of sulphuric acid.
19.
-3
3
-3
1.25 mol dm hydrochloric acid reacts completely with 25.0 cm of 1.0 mol dm sodium carbonate. (a) Write a balanced chemical equation for this reaction. …………………………………………………………………………………………………… (b) Calculate the number of mole of sodium carbonate used in this experiment.
(c) Calculate the volume of hydrochloric acid needed to exactly neutralize 25.0 cm 3 of 1.0 mol dm-3 sodium carbonate.
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Form 4 Score A+ Module
PAPER 2: STRUCTURE 1.
Diagram 1 shows the set-up of the apparatus for an experiment to determine the empirical formula of an oxide of copper.
Oxide of copper
Dry hydrogen gas
Heat Diagram 1 Table 1 shows the results of an a n experiment after heating, cooling and weighing are repeated until a constant weight is obtained. Substance Mass of combustion tube + porcelain dish Mass of combustion tube + porcelain dish + oxide of copper Mass of combustion tube + porcelain dish + copper
Mass(g) 18.75 g 20.75 g 20.35 g
Table 1 (a)
(b)
What is meant by empirical formula? ………..…………………………………………………………………………………………. [1 mark] Based on Table 5 results, (i) Calculate Calcula te the mass of copper and the mass of oxygen used in the experiment. experi ment.
[2 marks] (ii)
Calculate Calcula te the mole ratio rat io of copper atoms to oxygen atoms. Given that the relative atomic mass of Cu, 64; O ,16.
[2 marks] (iii)
State the empirical empirical formula of this oxide of copper.
(iv)
……….……………………………………………………………………………………… [1 mark] Write the chemical chemica l equation for the reaction reactio n in this experiment. experiment . ……………...……………………………………………………………………………… [1 mark]
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Form 4 Score A+ Module
(c)
Describe Describ e the steps that should be taken to ensure that all the air in in the combustion combust ion tube has been expelled , before any heating is carried out. …………………………..…………………………………………..………………………… . ……………………………….……………………………………………………………… ……………………………………...………………………………………………………… [3 marks]
2.
(a)
Culculate the relative molecular or formula masses of the following substances. (i) Ethanol, C 2H5OH. Given that relative atomic mass of H = 1, C = 12, O = 16.
[1 mark] (ii) Zinc nitrate, Zn(NO3)2 Given that relative atomic mass of O = 16 , N = 14, Zn = 65 .
[1 mark] (b)
A closed glass bottle contains 4 mol molecules of oxygen, O 2. (i)
What is the number of oxygen molecules in the bottle?
[1 mark] (ii)
How many oxygen atoms are there in the bottle?
[1 mark] (c)
Find the number of moles of atoms in a sample containing 9.03 × 10 20 atoms of copper.
[1 mark] (d)
Calculate the mass, in gram, of 3.5 moles of copper(II) ca rbonate, CuCO3. Given that relative formula mass of CuCO 3 = 124
[1 mark] (e)
When silver carbonate, Ag 2CO3 is heate heated, d, it will decompose to produce silver metal, carbon dioxide gas and oxygen gas as shown in the equation below.
2Ag2CO3(s)
4Ag(s) + 2CO2(g) +
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O2(g)
Form 4 Score A+ Module
A student heats 8.28 g silver carbonate. Calculate the volume of carbon dioxide gas, CO2 collected at room temperature. Given that relative atomic mass of C = 12, O =16, Ag = 108,
[3 marks] 3.
Diagram 3 shows 3.1 g of copper (II) carbonate being heated strongly in attest tube. The gas given out is passed into limewater in a test tube through a delivery tube.
Copper(II) carbonate Heat strongly
Lime water
Diagram 3 (a)
State the observation made when copper(II)carbonate powder is heated until the reaction is complete.
(b)
………………………………………………………………………………………………… [1 mark] Write the chemical equation to represent the reaction that takes place.
(c)
……………………………………………….………………………………………………… [1 mark] Calculate the number number of moles moles of copper(II)oxide produced.
[2 marks] (d)
Calculate the volume of gas produced at STP.
[2 marks] (e)
(i)
What can be observed observ ed if the product is heated in a stream of hydrogen gas?
(ii)
..……………………………………………………………………………………… [1 mark] Calculate Calculat e the mass of the substance substa nce produced. produce d.
[2 marks]
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Form 4 Score A+ Module
PAPER 2 : ESSAY
4. (a)
The information below is regarding substance X
Carbon 85.70%
Hydrogen 14.30%
Relative molecular mass = 56
(i)
Determine the empirical formula of substance X. [Given that the relative atomic mass of C = 12 , H = 1]
(ii)
Determine the molecular formula of substance X.
(iii)
Based on the answers in (a)(i) and (a)(ii) , compare and contrast the empirical formula and the molecular formula. [ 8 marks]
(b)
Magnesium can react actively with oxygen to form magnesium oxide. Describe an activity that can be carried out in the laboratory to determine the empirical formula of magnesium oxide. Include the calculations involved in your answer. Given that the relative atomic mass for O = 16, Mg = 24. [11 marks]
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Form 4 Score A+ Module
PAPER 3 : STRUCTURE 5.
A student carried out an experiment to determine the empirical empirical formula of magnesium oxide. The steps and set-up of apparatus of the experiment are shown in Diagram 5. 1. The crucible and lid are weighed. lid crucible
123.3632g
digital balance
2. The crucible, crucible, lid and magnesium powder are weighed. weighed.
Magnesium powder
128.1580g
3. The magnesium powder is heated until it reacts completely with oxygen. oxygen.
white fumes
heat
4. The crucible, crucibl e, lid and magnesium oxide are weighed when cooled.
magnesium oxide powder
131.3580g
Diagram 5
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Form 4 Score A+ Module
(a)
Complete the following table by stating the observations and related inferences in the experiment. Observations
Inferences
(i) ................................................
(i) ................................................................
....................................................
....................................................................
(ii) ...............................................
(ii) ...............................................................
....................................................
.....................................................................
(iii) ) ....................................................
(iii) .................... ...............................................
.................................................... .................................................................... [6 marks] (b)
Round off the reading to two decimal places and record it in the table below.
Description
Mass / g
The crucible and lid. The crucible, lid and magnesium powder. The crucible, lid and magenesium oxide.
(c)
(i)
Calculate
the mass of magnesium that has been used.
(ii)
Calculate
the mass of oxygen which reacted with magnesium.
(iii)
(d)
Determine the empirical formula for mula of magnesium magnesiu m oxide. Use the information that that the relative atomic mass, mass, O = 16, Mg = 24
The student wants to determine the empirical empirica l formula of lead(II) oxide. He used the steps and set-up of apparatus as the experiment before. Predict whether the empirical formula of lead(II) oxide can be determined. determin ed. Explain your answer. ...............................................................................................................................................................
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Form 4 Score A+ Module
CHEMISTRY SCORE A+ MODULE FORM 4
SET 2
Periodic Table of Elements Chemical Bonds
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Form 4 Score A+ Module
PERIODIC TABLE OF THE ELEMENTS Periodic Table of Elements 1
2
13 14 15 16 17 18
Transition elements
Group 1 : Alkali Metals Li Na K Rb Cs
2. 1 2. 8. 1 2. 8. 18. 1 2. 8. 18. 18. 1 2. 8. 18. 32. 18. 1
1. Each atom has one …………………………………………….…………………………………………. 2. That’s why the elements in the group have similar ………………….…………………….… properties. properties. 3. All atoms in the group can form ion with one positive charge. How? …………….……………………………………………………………………………………………. 4. The reactivity of alkali metals increases down the group. Why?
Atomic size increases.
Distance of valence electron from nucleus is further.
Attraction between nucleus and valence electron is weaker.
Easier to donate/ release the valence electron.
5. Chemical properties : Reaction With water.
Product Alkali and hydrogen gas
Chemical equation 2Li + 2H 2O 2LiOH + H2
With oxygen.
Oxide metal / base.
4 Li
Base dissolves in water.
Alkali
Li2O +
with halogen (chlorine, bromine, iodine)
Salt
2Li
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+
+
2 Li2O (white)
H2O
2LiOH
Cl2
2 LiCl (white)
O2
Form 4 Score A+ Module
Group 18 : Noble Gas
He Ne Ar Kr Xe Rn
2 stable / duplet electron electr on arrangement arra ngement 2. 8 2. 8. 8 2. 8. 18. 8 octet electron electr on arrangement arra ngement 2. 8. 18. 18. 8 2. 8. 18. 32. 18. 8
1. Elements in this group are in the form of monatomic. 2. They are chemically inert, whereas they do not easily …………………….………………………… , ……………………………………….or …………………………………………electrons with others. 3. This is because their outer shell is fully filled with ………………………...…… electrons (except He). 4. Physical Properties : i)
When going down the group, the atomic radius …………….…………………………………….. This is because ……………………………………………………………………….…………….
ii)
When going down the group, the melting point and boiling point ……………………….……….. This is because ………………………………………….………………………………………….
Group 17 : HALOGEN
F Cl Br I As
2. 7 2. 8. 7 2. 8. 18. 7 2. 8. 18. 18. 7 2. 8. 18. 32. 18. 7
1. Diatoms at room temperature. (Cl2, Br2, I2) 2. Each atom has seven …………………………………………………………………………………….. 3. That’s why the elements in the group have similar ……….…………………………………………….. 4. All atoms in the group can form ion with one ……………………………….………………….. charge. How? ………………………………………….…………….…………………………………………………..
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Form 4 Score A+ Module
5.
Chemical properties: Reaction Reactio n With water. With alkali. With metal (iron).
Product acid salts salt
Chemical equation Cl2 + H2O HCl + HOCl Cl2 + 2KOH KCl + KOCl + H2O 2Fe + 3Cl2 2FeCl3 (brownish)
6. The Melting Point Point and Boiling Point increases increases down Group 17. Why?
Molecular size increases. Forces between molecules become stronger. More heat energy is needed to overcome the forces.
Elements across the Period: 1. Element Na Mg Metals Oxide
Na 2O
MgO
Base
Al
Al2O3
Si Metalloid SiO2
P
P2O5
S Nonmetal SO2
Cl
Cl2O7
Acidic
Amphoteric
2. Changes of elements when across the p eriod atomic size decreases melting point increase then decreases electronegativity electronegativity increases from metals to non-metals Chemical properties from basic to a cidic. 3. Why the atomic size (atomic radius) r adius) decreases across the period? Proton numbers increase. The numbers of electrons in shells incr ease. The positive charges in nucleus increase. The force of attraction attra ction from nucleus towards all the electrons in the s hell increases. Thus the atomic size increase. Transition elements 1. State special characteristic of transition elements and examples. Special characteristic character istic Form coloured ions.
Example Cu2+ - blue, Cr 3+ - green, Fe3+ - brown
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Ar
Form 4 Score A+ Module
PAPER 2 – STRUCTURE
1.
Diagram 1 shows part of the Periodic Table of the Elements A, B, C, D, E and F do not represent the actual symbol of the elements.
A B
C
E
D
F
Diagram 1 Using the letters in the Periodic Table of the Elements in Diagram 1, answer the following questions. (a)
(i)
State the position of element B in the Periodic Table. ………………..…………………………………………………………………………………. [2 marks]
(ii)
Choose the element which exhibit different differ ent oxidation numbers in its compounds. ………………….………….……………………………………………………………………. [1 mark]
(b)
Element E combines with element A to form a compound. (i)
Write the chemical chemica l formula of this compound. …………………………………………….……………………………………………….……. [1 mark]
(ii)
State one physical property propert y of this compound. …………………………………………..………………………………………………………. [1 mark]
(c)
B and E have the same chemical chemica l properties. propert ies. (i)
Which element is more reactive? reacti ve? ……………………………….……………………………………………………………….…. [1 mark]
(ii)
Explain your answer in (c) (i). ……………….…………….……………………………………………………………………. …………………….……….……………………………………………………………………. [2 marks]
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Form 4 Score A+ Module
(d)
(i)
Which element exists as diatomic molecules? ……………………………………………………………………………...…………….…..…. [1 mark]
(ii)
Name the chemical chemica l bond in these diatomic molecules. …………….…………………………………………………………………….………………. [1 mark]
2.
Diagram 2 shows shows part of the Periodic Table of of the Elements. P, Q, R, S and T do not represent the actual symbol of the elements.
Group
P R
S
Q T
Period
Diagram 2 (a)
Using the Periodic Table of the Elements in Diagram 2, answer the following questions. (i)
Choose an element that is a halogen. ……………………………..……………………………………………....……………………. [1 mark]
(ii)
Which element is monoatomic? ……………………………..……………………………………………………..……………... [1 mark]
(iii)
Which element forms an amphotheric amphother ic oxide? …………………………………….……………….……………………………………….…… [1 mark]
(b)
Arrange P, Q, R, S and T according to increase increas e in size of the atoms. ………….………………………………………………………………………………………........... [1 mark]
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Form 4 Score A+ Module
(c)
Write the electron arrangement for an atom of element S. ……………………………………………………………………………..………………………….. [1 mark]
(d)
Write the formula for the ion formed from an atom of element T. ……………….………………………………………………………………….…………………….. [1 mark]
(e)
Why are elements P and Q placed in the same period? ……………………….………………………………………….…………………………………….. [1 mark]
(f)
When a small small piece of element R is put into into water, ROH solution is formed and hydrogen hydrogen gas is released. releas ed. State one observation when red litmus paper is put into the water. …………………….………………………………………………………………………………….. [1 mark]
(g)
State the common name of the elements between Group 2 and Group 13. ……………………….………………………………………………………………………………..
3.
The diagram 3 shows part of the Periodic Table of the Elements. A, B, C, D, E, F and G do not represent the actual symbol of the elements.
A D
B
C E
F G
Diagram 3 Using the letters in the Periodic Table of the Elements in Diagram 3, answer the following questions (a)
Write the formula for the ion formed from an atom of (i)
element D ………………………………………………………………..…………………………………. [1 mark]
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Form 4 Score A+ Module
(ii)
element B ………………………………….………………………………………………………………. [1 mark]
(b)
F is is a reactive metal that is is situated situated in Group 1. (i)
+
Give the number of electrons electr ons in ion F ? ……………………………………………………………………….…………………………. [1 mark]
(ii)
What is the electron electr on arrangement arra ngement of ion F+? ……………………………………….………….………………………………………………. [1 mark]
(c)
Which of the elements can be used as a catalyst? ……………………………………………..………………………………………………………….. [1 mark]
(d)
Element D reacts with with element E to form a compound (i)
Write the chemical chemica l formula of this compound ………………………………………….……………….………………………………………. [1 mark]
(ii)
Draw the diagram of the electron electron arrangement for the compound formed between D and E.
[2 marks] (iii)
State one condition conditio n by which which the compound in (d) (ii) conducts electricity? electric ity? Explain your answer. ………………………………………….……….………………………………………………. …………………………………….………….…………………………………………………. [2 marks]
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Form 4 Score A+ Module
PAPER 2 – ESSAY
4.
Diagram 4.1 and 4.2 show the diagrams of the electron arrangement for atoms of two elements from Group 17 in the Periodic Table of the Elements.
Diagram 4.1 (a)
Diagram 4.2
Based on Diagram 4.1 (i)
Write the electron arrangement for the atom of the element and name the element. [2 marks]
(ii)
Write a chemical equation for the reaction between this element and sodium hydroxide. [3 marks]
(b)
Compare the attractive forces between between the nuclei nuclei and the valence electrons electrons in the atoms in Diagram Diagram 4.1 and Diagram 4.2 and relate this to their respectively reactivity. [6 marks]
(c)
Another element in Group 17 is a black coloured solid. Predict the reactivity of this element in its reaction with sodium hydroxide compared to that of the element in the Diagram 4.2. [1 mark]
(d)
Diagram 4.3 shows the set up up of the apparatus to investigate investigate the reaction of an element element from Group 17 with iron metal.
Iron wool Chlorine gas Sodium hydroxide solution
Diagram 4.3 Part A
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Part B
Form 4 Score A+ Module
(i)
State two precautions that must be taken while carrying out the experiment. [2 marks]
(ii)
Describe and write the chemical equations for the reactions that occur in Part A and Part B. [6 marks]
PAPER 3 – STRUCTURE
5.
An experiment is carried carr ied out to investigate investigat e the statement stateme nt above. Table 5 shows the apparatus set up and the observations for the experiment to determine the reactivity of the Group 1 elements based on their reactions with water. Apparatus set-up
Observation Observatio n towards the metal
Lithium
water
Lithium moves slowly on the surface of the water with a “hiss” sound.
Potassium
)) )))) )
water
Potassium moves vigorously and randomly on the surface of the water with a “hiss” sound.
sodium
)) )
water
Sodium moves quickly and randomly on the surface of the water with a “ hiss” sound.
Table 5 (a)
State the variables that are involved in the experiment. Name of variables variabl es Action to be taken (i) Manipulated Manipula ted variable: variab le: (i) The way to manipulate manipulat e variable: variabl e:
(ii) Responding variable:
(ii) What to observe in the responding respond ing variable:
(iii) Controlled variable:
(iii) The way to maintain the controlled variable:
[6 marks]
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Form 4 Score A+ Module
(b)
State one hypothesis for the experiment. …………………………………… ……………………………………………….....………… ………….....……………...............………………………… …...............…………………………...... ...... …………………………………… …………………………………………………… ………………………....................………………….................. ………....................………………….................. [3 marks]
(c)
State the operational definition for the reaction. …………………………………… ……………………………………………….....………… ………….....……………...............…………………………...... …...............…………………………...... [3 marks]
(d) Based on the observations observa tions in the figure above, arrange lithium, potassium potass ium and sodium in the descending order of reactivi r eactivity ty of metals towards water.
Descending order of reactivity of metals towards water. [3 marks] (e)
Solution X was produced from the reaction of potassium with water. water. Classify the ions ions that exist exist in solution X into positive ions and negative ions. Positive Ions
Negative Ions
[ 3 marks]
PAPER 3 – ESSAY
6.
The reactivity of the alkali metals increases as you go down the group
Refering to the statement above, plan an experiment to prove it true by using the reactions of lithium, sodium and potassium with water. Your planning must include the following items: (a) (b) (c) (d) (e)
Problem statement All variables involved List of materials and apparatus Experimental Experimental procedure Tabulation of data [17 marks]
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Form 4 Score A+ Module
CHEMICAL BONDS FORMATION OF IONS Cations
+
Releases 1 electron
Half equation: + Li Li + e Lithium atom, Li
Lithium ion, + Li 2+
Releases 2 electrons
Half equation: 2+ Mg Mg + 2e
Magnesium atom, Mg
Magnesium ion, 2+ Mg
Anions
Receives 1 electron Half equation: F+e F
Fluorine atom, F
-
Fluoride ion, F
2Receives 2
Oxygen atom, O
Half equation: 2O + 2e O
2-
Oxide ion, O
Page 35 / 96
Form 4 Score A+ Module
FORMATION OF IONIC BONDS a)
Formation of sodium chloride compound, NaCl
-
+ +
Sodium atom
Chlorine atom
Sodium ion
Chloride ion
Explanation: The electron arrangement of sodium atom is 2.8.1 and chlorine atom is 2.8.7
To achieve octet electron arrangement; +
o
Sodium atom releases releas es one electron electr on to form sodium ion, Na .
o
Half equation: Na Na + e Chlorine atom receives recei ves one electron to form chloride ion, Cl .
+
-
Half equation: Cl + e Cl Sodium ion and chloride ion are attracted to one another by strong electrostatic force which called an ionic bond
Ionic compound NaCl is formed
FORMATION OF COVALENT BONDS
Example
X X
+
Oxygen atom
XX
XX
X
X XX XX
X
X
Oxygen molecule, O2
Oxygen atom
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X X
Form 4 Score A+ Module
Explanation The electron arrangement of oxygen atom is 2.6
An oxygen atom contribute 2 electron and attain / achieve the octet electron arrangement.
Two oxygen atom share 2 pairs of electron to one another to form a double covalent bond
A covalent molecule, O2 is formed
PAPER 2 : STRUCTURE 1.
Diagram 1 shows the symbols for atom of element X, Y, and Z.
Y
X
X
Y
Z Z
Diagram 1 (a)
(b)
(i)
Write the electron electro n arrangement arra ngement of atom X.
(ii)
……………………………...........……………..………………………………………… Write the electron electro n arrangement arra ngement of ion X.
(iii)
……………………………………………………………………………………..……. Draw the diagram diagra m to show the formation format ion of ion X
(iv)
Write the half-equation half-equa tion to show the formation for mation of ion X
(v)
………………………………………………………………………………………….. Explain the formation of ion X.
(i)
………………………………………………………………………………………… What is the proton number of element Y?
(ii)
………………………………………………………………………………………… Write the electron electro n arrangement arra ngement of atom Y. …………………………………………………………………………………………
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Form 4 Score A+ Module
(iii)
Write the electron electro n arrangement arra ngement of ion Y.
(iv)
…………………………………………..…………………………………………………… Draw the diagram diagra m to show the formation forma tion of ion Y.
(v)
Write the half-equation half-equa tion to show the formation for mation of ion Y. ………………………………………………………………..………………………………
(c)
(vi)
Explain the formation forma tion of ion Y.
(i)
……….……………………………………………………………………………………… What is the proton number of element Z? ...............................................................................................................................................
(ii)
Atom of of element element Z has a nucleon nucleon number of of 35. Calculate the number of of neutrons neutrons in atom Z. ………………………………………………………………………………………………
(iii)
(d)
Write the standard representation of element Z.
Element Y and Z are reacted to form a compound T. (i) Name the type of compound T.
(ii)
……….……………………………………………………………………………………… Draw the electron arrangement for the compound T.
(iii)
State one physical property of compound T. ………………………………………………………………………………………………
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Form 4 Score A+ Module
(e)
Element X can react with carbon to form a compound. [ Proton number of C = 6 ] (i)
Name the type of bond in the compound compou nd formed. for med.
(ii)
……………………………………………………………………………………………… Draw the electron arrangement arra ngement for the compound formed.
(iii)
State one physical property proper ty of compound formed. ………. ..……………………………………………………………………………………
2
Table 2 shows the proton proto n numbers of elements A, B and C. Elements
Proton Number
A B C
11 8 1 Table 2
a)
b)
(i)
Write the electron arrangement for atom A
(ii)
……….………………………………………………………….…………………….……. Write the electron electr on arrangement arrange ment for ion A
(iii)
………..........…………………………………………………….…………………….…… Draw the diagram to show the formation for mation of ion A
(iv)
Write halfhalf- equatio equation n to show the formation for mation of ion A
(i)
…………………………………………………….……………………………………… Write the electron arrangement for atom B ………………………………………………….…………………………………………
(ii)
Write the electron arrangement for ion B.
…….……………………………………………………………………………………… (iii)
Write halfhalf- equatio equation n to show the formation for mation of ion B ……………………………………………………………………………………………
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Form 4 Score A+ Module
c)
d)
A and B react to form a compound ( i) What type of bond in the compound formed?
(ii)
……………………………………………………………….........……………….……….. Draw the electron arrangement of the compound formed in (c)(i)
(iii)
State one physical property of the the compound formed
……………………………………………………………………………………………… C can react with B to form a compound. (i) What is the molecular formula of the compound formed?
(ii)
(iii)
(iv)
……....................…………………………......................................................................... Draw the electron arrangement arra ngement of the compound formed in (d)(i)
What is the relative molecular mass of the compound in d(i). [ Given that relative atomic mass C = 1; B= 16] ………..…………………………...............…………… ………..…………………………...............………………………………… ………………………………… …………… Name another compound that has the same physical properties as the compound formed. ………………………………………………………………………….............…………
Diagram 3 shows the position of several elements P, Q, R, S, T, U and W.
3
P
V
Q R
T U
S
W
Diagram 3
Page 40 / 96
X
Form 4 Score A+ Module
Using the symbols P, Q, R, S, T, U and W, answer the following questions. (a) Write the electron arrangement of
(b)
(i)
Atom R:….…………………….……
(ii)
Ion P:……………………………….
Explain the formation of ion U …….………………………………………………………………………………………………
(c)
……..…………………………………………………………………………………………….. (i) What is the formula for ion formed for med by Q
(ii)
(d)
……….....……………….………………………………… ……….....……………….…………………… …………………..........…………..……… ……..........…………..……… Write half- equation equation for (c) (i)
…....…………………………………………………………........………………..……… Atoms of P and U can reacted to form a compound. (i)
Name the type of bond in the compound formed between atom P and U
………….....……………….……………………………………………………………… (ii) Draw the electron arrangement for the compound formed.
(e)
4.
Atom V and T can also react to form a compound. Draw the electron arrangement for the compound formed.
Diagram 4 shows the chemical symbols of element sodium, s odium, oxygen, carbon and chlorine.
23
16
Na 11
12
O 8
19
C 6
Diagram 4
Page 41 / 96
F 9
Form 4 Score A+ Module
(a)
(b)
(c)
Write the electron arrangement of (i)
Sodium atom:………………………………..…..
(ii)
Oxide ion: ……………………………………….
(iii)
Carbon atom:........................................................
(iv)
Flouride ion:..................................................
State the period and the Group for Flourine in Periodic Table of element (i)
Period:………………………………………….
(ii)
Group:………………………………………….
Sodium atom and oxygen atom react to form a compound. (i)
Name the type of bond in the compound compou nd formed when sodium react with oxygen. …………..…………………………………………………….……………………………
(ii)
Draw the electron arrangement for the compound formed.
(d)
Carbon atom and Flourine atom can also react to form a compound. Draw the electron arrangement arra ngement for the compound formed.
(e)
Compare one physical property of compound formed (b) and (c). Explain your answer. ……………………………………………………………..........………………………………… …………………………………………………………………….........……………………….… ……………………………………………………….........………………………………….……
Page 42 / 96
Form 4 Score A+ Module
PAPER 2 : ESSAY
5
Table 5 shows the proton numbers of three elements. Element
Proton Number
Carbon, C Sodium, Na Chlorine, Cl
6 11 17 Table 5
(a)
State the valence electron electr on of the (i) Sodium atom (ii) Chlorine atom. [2 marks]
(b)
(i)
Select two elements that react to form an ionic compound. State your reason. r eason. [2 marks]
(ii)
Referring Referr ing to their proton number, explain how the compound compou nd in (b) ( i ) is formed. [6 marks]
(c)
(i)
Select two elements that react to form a covalent compound. State your reason. r eason. [2 marks]
(ii)
Referring Referr ing to their proton number, number, explain how the compound in (c )(i) is formed. [4 marks]
(d)
The compound in (b) has higher melting point than in (c). Explain why. [4 marks]
Page 43 / 96
Form 4 Score A+ Module
CHEMISTRY SCORE A+ MODULE FORM 4
SET 3
Electrochemistry
Page 44 / 96
Form 4 Score A+ Module
Electrolysis
1.
Define the meaning of electrolyte and non-electrolyte and respective examples. Electrolyte
Non-electrolyte
Meaning
Example
2.
Define electrolysis: ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..
3.
Energy change :
Electrolysis: Electrolys is: ……………………….. ………………………..….. ….. energy to ………………………………energy. Voltaic cell: ……………………………..energy to ………..……………………. energy. 4.
Write the half equation to represent the discharge of anion and cation.
Anion Hydroxide ion, OH-
Half equation
Cation Hydrogen ion, H+
Chloride ion, Cl-
Sodium ion, Na+
Bromide ion, Br
Silver ion, Ag+
Iodide ion, I
Lead (II)ion, 2+ Pb
Oxide ion, O2-
Copper(II) ion, 2+ Cu
Half equation
Aluminium ion, 3+ Al 6.
Products of electrolysis depend on three factors, they are a) ………………………………………………………….…………………………………..……….. b) ………………………………………………………………………………………………………. c) ……………………………………………………………………………………………………….
Page 45 / 96
Form 4 Score A+ Module
7.
Complete the electrochemical series below.
Cation
Anion
+
F
K
-
2+
Ca
-
Cl
2+
Zn
H
+
Ease of discharge increases
Diagram: Electrochemical Series
Page 46 / 96
Form 4 Score A+ Module
Sodium nitrate -3 solution, 0.5 mol dm
Carbon electrodes
Electrolysis of sodium nitrate solution.
8.
Describe Describ e the electrolysis electr olysis of sodium nitrate nitrat e solution using carbon electrodes. Anode
Write the formula of all ions present in the electrolyte. Write the formula of ion/ions which is/are attracted to anode and cathode. Which is selectively discharged? Give a reason.
Write the half equation to represent the discharge.
What will you observe at the electrode? Name the product. State the test to identify the product.
Page 47 / 96
Cathode
Form 4 Score A+ Module
Potassium chloride -3 solution, 0.5 mol dm Carbon electrodes
Electrolysis of potassium chloride solution
9.
Describe the electrolysis of potassium chloride solution using carbon electrodes. Anode
Write the formula of all ions present in the electrolyte. Write the formula of ion/ions which is/are attracted to anode and cathode. Which is selectively discharged? Give a reason.
Write the half equation to represent the discharge.
What will you observe at the electrode?
Name the product.
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Cathode
Form 4 Score A+ Module
Copper electrode Iron electrode
Copper(II)nitrate solution, 0.5 mol dm
-3
Electrolysis of copper (II) nitrate solution 10. Describe the electrolysis electrolysis of copper (II) nitrate solution solution using metal electrodes. electrodes.
Anode Write the formula of all ions present in the electrolyte. Write the formula of ion/ions which is/are attracted to anode cathode. and cathode. Which is selectively discharged? Give a reason.
Write the half equation to represent the discharge.
What will you observe at the electrodes?
Name the product. What will you observe to the electrolyte? Explain why?
Page 49 / 96
Cathode
Form 4 Score A+ Module
Voltaic cell / Simple cell
Zinc electrode Copper electrode
Copper(II)sulphate solution, 0.5 mol dm -3
11.
Describe the voltage cell. Negative terminal State all ions present in the electrolyte. Identify positive terminal and negative terminal. Explain why? Write half equation at negative terminal. Write the formula of ions which are moved to positive terminal. Which is selectively discharged? Give a reason. Half equation at positive terminal What will you observe at negative and positive terminal? What will you observe to the electrolyte? Explain why? Overall / Full ionic equation
Page 50 / 96
Positive terminal
Form 4 Score A+ Module
Application of electrolysis
12.
State the aim of electroplating electropla ting of metal. ………………………………………………………………………..……………………………….. ………………………………………………………………………..………………………………..
13.
The principal of electroplating. electroplating. (a) The thing to be electroplating must be ………………………………………………………………... (b) The electrolyte ………………………………………………….………….………………………….. (c) The anode ………………………………………………….………….……………………………….
14. To electroplate the spoon with silver.
Silver electrode
Iron spoon
Silver nitrate solution, 0.5 mol dm
(a)
(b)
-3
Write the half equation at silver electrode. ………………………………………………………………………………………………….. Write the half equation at iron spoon.
………………………………………………………………………………………………….. (c) State the observation at silver electrode. ………………………………………………………………………………………………….. (d)
State the observation at the iron spoon.
………………………………………………………………………………………………….. (e) An even and lasting layer of metal is obtained if: ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
Page 51 / 96
Form 4 Score A+ Module
15.
Purification Purifica tion of metal. (a) Things to be purified must be at …………………………………………….…………………….. (b) The other electrode ………………………….……………………………………….……………. (c) The electrolyte ……………………………………………………………………………….…….
The electrochemical series 16.
The electrochemical series ………………………………………………………………………………………………………..
17.
……………………………………………………………………………………………………….. The electrochemical series can be constructed based on; (a) The potential difference between two metals, in voltaic cell. The higher the voltage value, the ………………………………………………………………………………………… (b) The ability/ tendency of a metal to displace another metal from its salt solution. A metal which ………………………………………………… able to displace displace metal below it it in the series from its salt solution.
PAPER 2: STRUCTURE 1. Diagram 1 show the apparatus set-up used to electrolyze 0.1 mol dm -3 of sodium chloride solution using carbon electrodes.
Gas Q Gas P -3
0.1 mol dm of sodium chloride solution
Electrode X
Electrode Y _
+
Diagram 1 (a)
Name electrodes X and Y . ……………………………………………………………..………………………………………….. [1 mark]
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Form 4 Score A+ Module
(b)
Write the formula of all ions present in the solution.
(c)
…………………………………………………………………….………………………………….. [1 mark] (i) Name gas P collected in the test tube. …………………………………………………………………………………………………….. [1 mark] (ii) State a chemical test to confirm your answer to (c)(i). …………………………………………………………………………………………………….. [1 mark] (iii) Write a half equation for the reaction that takes place at electrode X .
(d)
(i)
……………………………………………………….………………………………………….. [1 mark] Name gas Q collected in the test tube.
…………………………………………………………….……………………………………….. [1 mark] (ii) State a chemical test to confirm your answer to (d)(i). …………………………………………………………………………………………………….. [1 mark] (iii) Write a half equation for the reaction that takes place at electrode Y .
(e)
…………………………………………………………………………………………………….. [1 mark] -3 What difference will it make if the experiment is repeated by using 2 mol dm of sodium chloride solution? Explain your answer. …………………………………………………………………………………………………….. …………………………………………………………………………………………………….. [2 marks]
2. Diagram 2 shows the apparatus set-up to carry out an electrolysis of aqueous copper(II) sulphate solution.
copper elecrodes
-3
carbon electrdes
0.2 mol dm of copper(II) sulphate solution Experiment I
Experiment II Diagram 2
(a)
Write the formula of all the ions present in the copper(II) sulphate solution. ………………………………………………………………………………………………….. [1 mark]
Page 53 / 96
Form 4 Score A+ Module
(b)
(i)
Name the product produced at the anode in Experiment Experi ment I.
………………………………………………………………………………………………….. [1 mark] (ii) Write a half equation for the reaction react ion that takes place at this electrode. electr ode.
(c)
………………………………………………………………………………………………….. [1 mark] (i) Name the product produced at the anode in Experiment Experi ment II. ………………………………………………………………………………………………….. [1 mark] (ii) Write a half equation equation for the reaction react ion that takes place at this electrode. electro de. ………………………………………………………………………………………………….. [1 mark]
(d) (i)
What happen to the intensity of the blue copper(II) copper(I I) sulphate sulphat e solution in Experiment I? ………………………………………………………………………………………………….. [1 mark]
(ii)
(e)
Explain your answer in (d) (i).
………………………………………………………………………………………………….. [1 mark] (i) What happen to the intensity of of the blue copper(II) copper(I I) sulphate sulphat e solution in Experiment II? ………………………………………………………………………………………………….. [1 mark] (ii) Explain your answer in (e) (i). ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. [1 mark]
3.
Diagram 3 shows a simple cell
V
electrode
electrode X
electrolyte Diagram 3
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Y
Form 4 Score A+ Module
Two different electrodes are immersed into an electrolyte. The voltage of the cell is recorded. The experiment is repeated by using different pairs of electrode. Table 3 shows the results obtained. The metals of which electrodes V, W, X, Y and Z ar e made of, for divalent ions. Experiment
Pairs of electrodes
Positive terminal
Negative terminal
Voltage/V
1
X/Y
Y
X
0.70
2
X/Z
X
Z
1.05
3
X/W
X
W
1.55
4
Y/V
V
Y
0.50
Table 3
(a)
Suggest a suitable electrolyte for the above experiments.
(b)
…………………………………….………………………………………………………………….. [1 mark] State the direction of the flow of electrons in Experiment 1 which used electrodes X and Y .
(c)
(d)
……………………………………….………….…………………………………………………….. [1 mark] Write half equation for the reaction reacti on that takes takes place at the negative terminal termina l in Experiment Experi ment 2 which used electrodes X and Z . ………………………………………………..……………………………………………………….. [1 mark] State a hypothesis hypothesis for the above experiments.
………………………………………………………………………………………………………….. [1 mark] (e) Arrange the metals V, W, X, Y and Z in decreasing order in the Electrochemistry Series.
(f)
………………………………………………..……………………………………………………….. [1 mark] A chemical cell is set-up using electrodes Z and V . (i) State the negative terminal of the cell. …………………………………………….………………………………………………………….. [1 mark] (ii) Calculate the voltage of the cell.
[1 mark] (g)
(i)
State the pair of electrodes electr odes that will give the highest voltage reading.
………………………………………………………………………………………………………….. [1 mark] (ii) Calculate Calcula te the voltage of the cell.
[1 mark]
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Form 4 Score A+ Module
PAPER 2 : ESSAY 4.
(a)
Ethanoic acid solution is is electrolysed electrolys ed by using platinum electrode. What is produced at the cathode? Write a half equation for the reaction that occurs at the cathode. [2 marks]
(b)
Diagram Diagra m 4 shows Cell X and Cell Y.
V
Zinc plate
Copper plate
copper electrode
copper(II) nitrate Cell X
Cell Y
Diagram 4
Cell X is a chemical cell while cell Y is an electrolytic cell. Compare cell X and cell Y. [8 marks] (c) A student wants to purify an impure copper plate by the pr ocess of electrolysis. Design an experiment in the laboratory to purify the impure copper plate. Your answer should include the following: materials and apparatus needed a diagram with the arrangement of apparatus the procedure observation chemical equation involved [10 marks] PAPER 3 : STRUCTURE 5.
A student carries out an experiment to study the potential difference between two types of different metals. The apparatus arrangement used is shown in Diagram 5.
After experiment
Before experiment
V
V
zinc plate
Zinc plate iron plate co
er II nitrate
Diagram 5
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iron plate
Form 4 Score A+ Module
(a)
State the observation and inference involved in the experiment in the table below. Metal plate
Observation
Inference
Zinc Iron
(b)
The student repeated the experiment by replacing the iron metal with copper metal, aluminium metal and magnesium metal. Table 5 shows the voltage reading obtained from the metal pairs. Metal pairs
Negative terminal
Positive terminal
Voltage/V
Zinc – iron
Zinc
Iron
0.4
Zinc – copper
Zinc
Copper
1.1
Zinc – almunium
Aluminium
Zinc
0.8
Zinc – magnesium magnesiu m
Magnesium Magnesiu m
Zinc
1.4
Table 5
Based on the information above, complete the table below. Type of variables
Action to be taken
(i) Manipulated Manipulate d variables :
(i) Way to change the manipula manipulated ted variables variabl es :
___________________________
_________________________________
(ii) Responding variables variab les :
(ii) How do these variables respond:
___________________________
_________________________________
(iii) Constant variables :
(iii) Way to fix the constant variables :
___________________________
_________________________________
[6 marks] (c)
State the hypothesis of the experiment …………………………………………………………………………………………………..
(d)
If the experiment is repeated by using lead metal to replace iron metal, predict the possible reading recorded by the voltmeter. …………………………………………………………………………………………………..
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Form 4 Score A+ Module
6. Diagram 6 shows two set-up apparatus apparat us used to electrolyzed 0.001 mol mol dm-3 hydrochloric acid and 1.0 mol dm-3 hydrochloric acid by using carbon electrodes.
Carbon electrode
-3
-3
0.001 mol dm hydrochloric
acid
1.0 mol dm hydrochloric
acid
Diagram 6 (a)
State a suitable hypothesis for the experiment. …………………………………………………………………………………………………..
(b)
State all the variables variabl es involved in the experiment (i) Manipulated variable ………………………………………………………………………………………………….. (ii) Responding variable ………………………………………………………………………………………………….. (iii) Constant variables …………………………………………………………………………………………………..
(c) Write the observations at the anode and cathode for both sets of experiment. Electrolyte Terminal
Set 1 ( 0.001 mol dm-3 hydrochloric acid )
Set 2 ( 1.0 mol dm-3 hydrochloric hydrochloric acid )
Anode
Cathode
(d)
Write half-equation half-e quation for the discharge dischar ge of ions at anode for Set 1 and Set 2. ………………………………………………………………………………………………….. ………………………………………...…………………………………………………………..
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Form 4 Score A+ Module
(e)
Predict the observation observati on at the anode and cathode cathod e when 0.0001 mol dm-3 potassium nitrate solution is electrolysed. ………………………………………………………………………………………………….. …………………………………………………………………………………………………..
PAPER 3 : ESSAY 7.
“Concentration of ions used during electrolysis electrolysis affects the product of electrolysis at the anode”. Using sodium chloride solution, describe an experiment to prove the above statement. Your answer should include: (a) (b) (c) (d) (e) (f)
Problem statement Hypothesis Variables Materials and apparatus used Procedure of the experiment Tabulation of data
The further the distance between two metals in the electrochemical series, the bigger the potential difference . 8.
You are given the copper strip, strip, lead lead strip, iron iron strip, zinc strip, strip, aluminium aluminium strip, magnesium magnesium strip and copper(II) sulphate solution.Referring solution.Referring to the statement above, plan a laboratory experiment experiment to construct c onstruct the electrochemical series of the potential differences using different pair of metals. Your explanation should include all the followings: (a) (b) (c ) (d) (e) (f)
Aim of the experment All the variables Statement of the hypothesis List of materials and apparatus Procedure of the experiment Tabulation of data [ 17 marks ]
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Form 4 Score A+ Module
CHEMISTRY SCORE A+ MODULE FORM 4
SET 4
Acids and Base Salts
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Form 4 Score A+ Module
ACID AND BASES 1.
+
+
hydroxonium, H3 O when An acid is a chemical compound that produce hydrogen ion, H or hydroxonium, dissolves in water. HCl + H2O H3O+ + ClH2O
HCl
+
-
H + Cl
2.
An acid shows its acidic properties only in the presence of water. of water.
3.
A base is defines as a chemical substance that can neutralise an acid to produce a salt and water. Example: CuO + 2HCl
4.
CuCl2 + H2O
An alkali is defined as a chemical compound that dissolves in water to produce hydroxide ions, OH-. Example: HO 2
KOH 5.
K+ + OH-
Define weak acid : ...............................……………………………………………………………………………...
6.
Define strong acid : ...............................……………………………………………………………………………...
7.
Define strong alkali : ...............................……………………………………………………………………………...
8.
Define weak alkali: ...............................……………………………………………………………………………...
9.
10.
Define basicity : the number of ionisable ............................ ........................... of an acid.
atoms per molecule
Using a suitable examples explain what is meant by a) Monoprotic acid : ...............................………………………………………………………………………… b)
Diprotic acid : ...............................…………………………………………………………………………
c)
Triprotic acid : ...............................…………………………………………………………………………
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Form 4 Score A+ Module
11.
Write an equation of dissociation for t he following acid. a) Nitric acid : ...............................………………………………………………………… ...............................…………………………… …………………………………………… ……………… b)
Ethanoic acid : ...............................………………………………………………………… ...............................…………………………… …………………………………………… ………………
c)
Carbonic acid : ...............................……………………………………………… ...............................…………………………… ………………………………………… ………………………… …
d)
Sulphuric acid : ...............................………………………………………………………… ...............................…………………………… …………………………………………… ………………
e)
Chemical properties of acid. Reaction
With reactive metal
Product
Salt and hydrogen gas
Example and Chemical equation Zn + 2HCl ZnCl2 + H2
PAPER 2 : STRUCTURE
1.
An experiment is carried out in the laboratory to determine the end point of the reaction between 25.0 3 -3 cm of potassium hydroxide solution and 1.0 moldm of sulphuric acid. Phenolphthalein is used in the titration to detect the end point of the reaction. diagram 1 shows the set-up of apparatus for the titration.
Sulphuric acid -3 1.0 moldm
Diagram 1
Potassium hydroxide + phenolphthalein
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Form 4 Score A+ Module
The volume of sulphuric acid added and the change of the colour of potassium hydroxide solution shown in the Table 1 below. Volume of sulphuric acid (cm3) Colour of potassium hydroxide solution
4,5
4.6
4.7
4.8
Pink
4.9
5.0
5.1
5.2
5.3
Colourless
Table 1
(a)
Name the chemical reaction between potassium hydroxide solution a nd sulphuric acid.
(b)
…………………………..................……………… …………………………..................……………………………………… ……………………………… ……… [1 mark] Write a chemical equation for the reaction. ………………………………................……………… ………………………………................……………………………………… ……………………………. …….
(c)
[1 mark] Write the formula of ions which are present in t he conical flask when the volume of s ulphuric acid added is: 3 (i) 4.5 cm ................................................................................................................................... (ii)
5.0 cm3 ................................................................................................................................... [2 marks]
(d)
What is the volume of sulphuric acid needed to neutralise 25 cm3 potassium hydroxide solution? …..................................................................................................................................... [1 mark]
(e)
(f)
Calculate the concentration of potassium hydroxide solution in this experiment.
[2 marks] If sulphuric acid is replaced with nitric a cid with the same molarity, predict the volume of nitric acid require to n eutralise 25.0 cm3 of the the potassium hydroxide solution. Explain why. .................................................................................................................................... .................................................................................................................................... [2 marks]
2.
Hydrogen chloride gas is dissolved in two different solvent, producing solutions X and Y.
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Form 4 Score A+ Module
Experiment I and II are carried out. Table 2 below shows the results of the experiment.
Observations Experiment Solution X
Solution Y
I
Marble chips added into solutions
Gas bubbles
No changes
II
Electrical conductivity
Deflection of ammeter reading
No deflection of ammeter reading
Table 2
a)
Name a suitable solvent to produce (i) Solution X
(ii)
..................................................................................................................................... Solution Y ..................................................................................................................................... [2 marks]
b)
(i)
(ii)
Which solution shows acidic properties ................................................................................................................................. What is the role of the solvent used to produce the acid in (b)(i) ................................................................................................................................. ................................................................................................................................. [2 marks]
c)
(i)
(ii)
Name the gas produce in Experiment I ................................................................................................................................ Describe a chemical test to verify the gas in (c)(i). ................................................................................................................................. ................................................................................................................................ [3 marks]
d)
Solution X can conduct electricity but solution Y cannot. Explain this statement. .......................................................................................................................................... .......................................................................................................................................... [2 marks]
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Form 4 Score A+ Module
3.
Table 3, below shows the pH value of four solutions. The solutions are of the same concentration Solution
W
X
Y
Z
pH
1
5
7
14
Table 3
a)
(i)
Name one example of solution Z.
(ii)
................................................................................................................................. Write a chemical equation for for the reaction of Z in a(i) a(i) with with sulphuric acid. .................................................................................................................................
(iii)
Name the chemical chemical reaction occur in a(ii). ................................................................................................................................. [3 marks]
b)
Which solution possibly can be sodium sulphate? .......................................................................................................................................... [1 mark]
c)
(i)
(ii)
Which solution can change a blue litmus paper to red? ................................................................................................................................. State one test to prove the chemical chemical property of c(i) c(i) without without using an indicator. ................................................................................................................................. ................................................................................................................................. …………………………………………………………………………………….
[3 marks] d)
Explain why solution W and Solution a nd solution X have different pH val ues. ..................................................................................................................................... ..................................................................................................................................... [2 marks]
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Form 4 Score A+ Module
Dry hydrogen chloride gas
Filter funnel
Methyl benzene ` Beaker A
Dry hydrogen chloride gas
Filter funnel Water
Beaker B
4.
Figure above shows the arrangement of apparatus used to prepare hydrogen chloride in methyl benzene and in water respectively. resp ectively. a) What is the purpose of using filter funnels funnels in this experiment experiment ? ................................................................................................................................................ [1 mark] b)
(i)
What is observed when a piece of magnesium magnesium ribbon is placed in Beaker A and Beaker B respectively. Beaker A : .................................................................................................................
(ii)
Beaker B :................................................................................................................. State the reason for your answer in b(i) ................................................................................................................................... ................................................................................................................................. [3 marks]
c) Name the types of particles present in Beaker A ; ........................................................................................................................ Beaker B : ........................................................................................................................ [2 marks]
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Form 4 Score A+ Module
d) Water is added to the solution i n Beaker A and the mixture is then shaken. W hen sodium carbonate solution is added, effervesence occurs. (i)
Name the gas and suggest a suitable suitable test to identify the gas evolved. evolved.
(ii)
................................................................................................................................ State the role of water that caused t he liberation of the gas.
(iii)
................................................................................................................................. Write the ionic equation for the rea ction involving the liberation o f the gas. .................................................................................................................................. [3 marks]
5.
Diagram 5 shows four test tubes contain dry glacial ethanoic acid, aqueous solution of dilute hydrochloric acid and aqueous solutio n of X.
Dry glacial ethanoic acid Blue litmus paper P
Aqueous solution of ethanoic acid 0.1 moldm-3
Dilute hydrochloric acid
Blue litmus paper
Blue litmus paper Q
ethanoic acid,
Aqueous solution of X
R
S
Diagram 5
a)
(i)
State the colour change of the litmus paper in test tubes Q and R. ................................................................................................................................
(ii)
Write the formula of ion which which caused caused the colour change of of the litmus paper. ..................................................................................................................................... [2 marks]
b)
Is there any changes of colour of of the litmus litmus paper in test tube P? Explain why. why. .............................................................................................................................................. .............................................................................................................................................. [2 marks]
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Form 4 Score A+ Module
c)
Table 5 shows the pH value of aqueous solution of ethanoic acid and of the same molarity. Type of acid
Molarity pH value
aqueous solution of ethanoic acid 0.1 moldm moldm-3 3.0
dilute hydrochloric acid
dilute hydrochloric acid
0.1 moldm-3 1.0
Table 5 Explain why the pH value of aqueous solution of ethanoic acid is higher than the pH value of dilute hydrochloric acid. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. d)
[2 marks] Calcium carbonate powder is added into test tube R. Write the chemical chemical equation for the reaction that takes place. .................................................................................................................................................. [1 mark]
e)
Aqueous solution of X is an acidic solution. As a chemistry student, describe briefly how you are able to prove that X is an acidi c solution. You are not allow to use lit mus paper, pH meter or any indicators. Procedure:
.................................................................................................................................................. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... [3 marks] Observation:
................................................................................................................................................... .................................................................................................................................................. [1 mark]
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Form 4 Score A+ Module
6.
(a)
A student carried out an experiment to study the pH of a few aqueous solutions using pH The results were tabulated below. Aqueous solution
P
Q
R
S
T
U
pH
13
7
4
8
20
1
paper.
Table 6
Which of the solution in the table above could be (i)
Distilled water
(ii)
…………………………………………………………………………….………… Vinegar ……………………………………………………………………………….………
(iii)
Sodium hydroxide …………………………………………………..…………………………………...
(iv)
Hydrochloric acid ………………………………….……………………………………………...……. [4 marks]
b)
(i)
An apple contains maleic maleic acid C4H8O5 which which is a weak acid, What is meant by weak acid ? ……………………………………………………………………………….………
(ii) The pH of 1.0 mol mol dm-3 maleic acid solution is higher than hydrochloric acid with the same concentration. Explain why. …………………………………………………………………………...………….. ………………………………………………………………………………………. [2 marks] c)
Zinc powder is added to the test tube containing hydrochloric acid. (i)
Name the gas released. …………………………………………………………………………….…………
(ii)
Describe a chemical test to identify the gas. …………………………………………………………………………….………… …………………………………………………………………………….…………
(iii) Write a balanced balanced equation equation for the reaction. reaction. ………………………………………………………………………….……………
[3 m a rks rks]
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Form 4 Score A+ Module
PAPER 2: ESSAY
7.
(a)
(i)
What is meant by ‘standard solution’ ?,
[1 mark] (ii) Describe how 100cm of 2.0 moldm sodium hydroxide solution can be prepared in the school laboratory, Your description should include the calculation Use the information, Relative atomic mass of Na = 23, O =16 , H = 1 [7 marks] -3 Using the 1.0 mol dm sodium hydroxide solution from (a) above. Describe how you would determine the unknown concentration of a sample of hydrochloric acid, HCl using the titration method. 3
(b)
-3
You may use either methyl orange or phenolphthalein as indicator. Include, in your answer, the chemical equation and calculation. [12 marks] 8.
(a)
The following information is about sodium hydroxide solution and ammonia solution.
pH of sodium hydroxide solution 1.0 mol dm-3 is 14
pH of ammonia solution 1.0 mol mol dm is 10
-3
Explain why both solutions have different pH value. [6 marks] (b)
The label of a reagent bottle was dirty caused by a chemical substance. substance. The reagent is suspected suspected to contain dilute hydrochloric acid. Describe two chemical tests which can be used to identify the chemical chemical solution is dilute hydrochloric acid.
solution if the [8 marks]
(c)
Glacial ethanoic ethanoic acid acid does not release any gas gas when it is poured into pieces of calcium calcium carbonate. However, effervescence occurs when several drops of water are added into the mixture of ethanoic acid and pieces of calcium carbonate. Explain the statement. [ 6 marks]
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Form 4 Score A+ Module
PAPER 3: STRUCTURE
9.
Diagram 9 shows the results of titration between sulphuric acid and sodium hydroxide solution.
1.0 mol dm-3 Sulphuric acid, H2SO4
Initial reading
Final reading
25.0 cm3 sodium hydroxide, NaOH solution + phenolphthalein DIAGRAM 9
(a)
Based on the diagram 2, record record the final and initial burette readings of the burette.
Final reading
=
…………………. cm3
Initial reading
=
…………………. cm3
=
………………… cm
Volume of H2SO4 used
3
[3 marks] (b)
Construct a table that can be be used used to record the result result of the experiment.
[3 marks]
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Form 4 Score A+ Module
(c)
(d)
(i)
State the colour change in the solution.
(ii)
……………………………………………………………………………………… [3 marks] State the inference of the colour change.
…….………………………………………………………………………………… [3 marks] Write the operational definition for the neutralisation. …………………………………………………………………………………………… …………………………………………………………………………………………… [3 marks]
(e)
You are given three examples examples of acids; sulphuric acid, ethanoic ethanoic acid and and hydrochloric acid. Classify them into monoprotic and diprotic acids.
[3 marks] (f)
Based on the titration results, calculate the molarity of sodium hydroxide solution used used . Given the chemical equation for the neutralisation is as follow: 2NaOH + H2SO4
Na2SO4 + 2H2O
[3 marks]
10.
A student student carried carried out two experiments experiments to determine the concentration concentration of HX acid acid solution. Experiment I Titration of HX acid solution of unknown concentration with 20cm3 of sodium hydroxide solution 1.0 mol dm-3 using phenolftalein as indicator.
Experiment II 3
Titration of similar HX acid solution of difference difference concentration with 20cm of sodium -3
hydroxide solution 1.0 mol dm using phenolftalein as indicator.
Page 72 / 96
Form 4 Score A+ Module
Diagram 10, shows the initial and final burette readings for both experiments. Experiment 1
0
20
1
21
Initial burette reading
Final burette reading
Experiment II
15
25
16
26
Initial burette reading
Final burette reading Diagram 10
(a)
Construct a table to record the initial and final burette readings and the volumes of the acid used for both experiments.
[ 3 marks] (b)
State the colour change of phenolftalein in the titration.
………………………………………………………………….................……………….. [ 3 marks]
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Form 4 Score A+ Module
(c)
The chemical equation for the reaction in the experiment is : HX +
NaOH
NaX
+
H2O
Calculate the concentration of HX acid solutions used in both experiments. (i)
Experiment I
(ii)
Experiment II
[ 3 marks] (d)
State the hypothesis in this experiment.
…………………..……….............………………………………………………………… .......………………………………………………………………………………………… [ 3 marks] (e)
If HX acid is replaced replaced with sulphuric acid of the same concentration, it is found found that the volume of the sulphuric sulphuric acid used in the titration is half of the volume of HX acid. why.
Explain
……………………………………………………………………………………….......… ……………………………………………………………………………………….......… …………………………………………………………………………………….......…… [ 3 marks] PAPER 3 : ESSAY
11. Solid sodium hydroxide does not give any effect on dry red litmus paper. On the other hand, sodium hydroxide solution changes dry red litmus paper to blue.
With reference to the above statement, plan an experiment in the laboratory to study the role of water on the properties of alkali. Your planning of experiment must include the following: a) Problem statement b) Hypothesis c) List of materials and apparatus d) Procedure e) Tabulation of data
[17 marks]
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Form 4 Score A+ Module
SALTS 1.
A salt is an ionic compound that is
formed when the ………………………… … ion in +
an acid is replaced by a …………………………………… ion or ammonium ion (NH4 ). 2.
Solubility of salts. Type of salt Sodium, potassium and ammonium salts Nitrate salts
Solubility in water All are soluble.
Sulphate salts Chloride salts Carbonate salts
3.
Preparation of soluble salts. Preparation of soluble salts An acid reacts with reactive metal.
4.
Example / Reactants Magnesium and hydrochloric acid
Chemical equation Mg + 2HCl MgCl2 + H2
Insoluble salts can be prepared by ………………………….…. in double decomposition reaction. Example: Silver nitrate solution reacts with sodium chloride solution, white precipitate formed. Chemical equation:
AgNO AgNO3 +
Ionic equation :
Ag+
AgCl(s) + NaNO3 NaCl NaCl AgCl(s)
+ Cl- AgCl(s)
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Form 4 Score A+ Module
5.
Quantitive analysis of salts. (a) Colour of salts Colour White or colourless
Solid
Solution
Sodium,potassium,magnesium,, ammonium, Sodium,potassium,magnesium
Na+,K+,Mg2+,
Lead ,chlorides, sulphates,nitrates.
Pb2+, Zn2+, NH4+
Green
Blue
Brown
(b)
Action of heat on Carbonate and Nitrate salts. Type of salt
Colour of salt before heating
Colour of residue Hot
Copper (II) carbonate Lead (II) carbonate
White
Brown
Lead (II) carbonate Zinc carbonate Magnesium nitrate Zinc nitrate Sodium nitrate
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Cold
Form 4 Score A+ Module
Test for Anions.
(c)
Summarise the tests used to identify anions in the table below. Anion
Test
Observation and inference
Carbonate, CO32-
Add 2 cm3 hydrochloric acid, bubble the gas produced through lime water.
Chloride, Cl Sulphate, SO42-
White precipitate is formed, sulphate ion is present.
Nitrate, NO3
(d)
Specific tests for cations
Cation
Reagent
Observation
Ammonium, NH4+
Iron (II), 2+ Fe
Iron (III), Fe3+
Lead (II), Pb2+
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Form 4 Score A+ Module
PAPER 2: STRUCTURE
Oxide M
Compound J
(Brown when hot, yellow when cooled) Heat
+ dilute nitric acid
+ Gas L (Colourless)
White precipitate Q (Dissolved in excess sodium hydroxide solution)
Reaction I
+ NaOH (aq)
Reaction II
Colourless J solution
White precipitate R + H 2 2 SO 4 (aq)
Diagram 1 1.
Diagram 1 shows a series of chemical test done by a student to identify a compound J. a)
b)
c)
With reference to reaction I, white precipitate Q is formed when reacts with sodium hydroxide hydroxide solution and it is soluble soluble in excess excess sodium hydroxide solution. Name all the ions which are probably present in solution J. .............................................................................................................................................................. [1 mark] Referring to reaction I and II, Name the cation that is present in solution J. .............................................................................................................................................................. [1 mark] Write the ionic equation for the reaction forming the white precipitate, R. ………………………………………………………………………………………………………. [1 mark]
d)
Name two cations which produce white white precipitates precipitates with with sodium hydroxide solution that do not not dissolve in excess sodium hydroxide h ydroxide solution. ………………………….……...…………………………………………………………………… [1 mark]
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Form 4 Score A+ Module
(e)
Describe a confirmatory test which you can use to differentiate the cations you named in (d). ........................................................................................................................................................... ........................................................................................................................................................... ........................................................................................................................................................... ........................................................................................................................................................... [4 marks]
2.
An experiment to investigate the effect of heat on solid lead (II) carbonate is shown on diagram 2. Boiling tube
Lead (II) carbonate
Heat Lime water
Diagram 2 (a)
(i)
State two observations of the above experiment. ………………………………………………………………………………………………… …………………………………………………………………………………………………
… [2 marks] (ii)
Write an equation for the reaction ……………………………………………………………………………………………….. [1 mark]
(iii)
Name the residue formed inside the boiling tube at at the end of the experiment experiment …………………..…..………………………………………………………………………. [1 mark]
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Form 4 Score A+ Module
(b)
The result of the experiment is shown in Table 2. [Relative atomic mass: Pb=207, C=12, O=16; 1 mol of gas occupies 24dm3 at room temperature and pressure] Substance Mass of boiling tube Mass of boiling tube and lead (II) carbonate before heating heatin g Mass of boiling tube and residue after heating
Mass (g) 12.45 23.13 22.56
Table 2
(i)
Calculate the mass lead (II) carbonate used.
(ii)
Calculate the mass of residue formed.
(iii)
Calculate the volume of carbon dioxide evolved at room temperature and pressure.
[2 marks]
[2 marks]
[2 marks] (c)
All the residue is formed during the heating of lead (II) carbonate was dissolved in dilute nitric acid to form a colourless solution. When excess of sulphuric acid is added to the colourless solution, a white precipitate is formed. (i) Name the white precipitate precipit ate formed.
(ii)
…………………..…………………………………………………………………………… [1 mark] Write an ionic equation for the reacti on. …………………..…………………………………………………………………………… [1 mark]
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Form 4 Score A+ Module
3.
Diagram 3 shows the formation of zinc nitrate and its conversion to other substances + dilute nitric acid
Zinc nitrate
W
Nitrogen dioxide + Gas X
+ dilute NaOH (aq) + potassium iodide solution
+ sodium carbonate solution
Y + sodium nitrate R + sodium nitrate Z + potassium nitrate
Diagram 3 (a)
(b)
W is a white powder which reacts with dilute nitric acid. The powder is yellow in hot. Give the name of W. ……………………………………………………………………………………………………… [1 mark] A small amount of sodium hydroxide solution is added to zinc nitrate solution. Precipitate Y is produced. (i) Write the chemical formula of Y.
(ii)
(c)
(i)
(ii)
…………………..…………………………………………………………………………… [1 mark] Describe what happens when sodium hydroxide is added to zinc nitrate. ………………..……………………………………………………………………………… [1 mark] Zinc nitrate can be converted to nitrogen dioxide and gas X. How can this conversion be carried out? ………………..……………………………………………………………………………… [1 mark] Name gas X ………………….……………………………………………………………………………. [ 1 mark]
(iii)
Describe the observation during the experiment. ………………….……………………………………………………………………………. ………………….……………………………………………………………………………. [1 mark]
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Form 4 Score A+ Module
(d)
When potassium iodide is added to zinc nitrate solution a precipitation precipitation takes place. (i) Name the substance Z
(ii)
(e)
………………………………………..……………………………………………………… [1 mark] Write an ionic equation to show how Z is produced.
…………………………………….…………………………………………………………. [1 mark] Write the chemical formula of substance R ……………………………………………………………………………………………………….. [1 mark]
PAPER 2: ESSAY
4. (a)
The following are three examples of sulphate salts that can be prepared in the laboratory. Potassium sulphate Lead (II) sulphate Zinc sulphate (i)
From these examples, identify soluble and insoluble salts [2 marks]
(ii)
State the reactants for the preparation of the insoluble salts in 4 (a) (i). [2 marks]
(b)
With the aid of a labeled diagram, explain the crystallization method for preparing a soluble salt from its saturated solution. [6 marks]
(c)
You are given a solution that contains a mixture of iron (III) nitrate and iron (III) chloride. chloride. Describe the confirmatory test to determine the presence of cation and anion in the solution. Your description must include all the materials used, observation and conclusion. [10 marks]
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Form 4 Score A+ Module
5. (a)
Lead (II) sulphate is insoluble in water. Describe the preparation of lead (II) sulphate in the laboratory. In your description, include the reagents an d chemical equation involved. [10 marks]
(b)
Table 5 shows shows the observations from some tests carried out on salt X. Test
Observation
I: Heating on salt X solid II: Salt X solution is mixed with excess aqueous ammonia
A metal oxide is formed and a brown gas is given off. A white precipitate which is insoluble in excess ammonia is formed. formed. Table 5
Based on the information in Table 5. (i)
Identify anion that is present in Test I and describe a chemical test to verify the anion. [4 marks]
(ii)
Identify cations.
two
cations that are present in Test II and describe a chemical test to verify the [6 marks]
PAPER 3: STRUCTURE
6.
Seven test tubes of the same size are labelled 1 to 7. A fixed volume of 5.0 cm3 of 1.0 moldm-3 potassium chromate (VI) solution is placed in each of the seven test tubes. Varying amounts of 1.0 moldm-3 of a nitrate salt of metal M is added to each test tube. For example, 1 cm3 to test tube 1, 2 cm3 of test tube 2, and so on until 7 cm3 is added to test tube 7. The height of the yellow precipitate formed in each test tube are recorded in the table 6. Test tube Height of precipitate (cm)
1 1.0
2 2.0
3 3.0
4 4.0
5 5.0
6 5.0
7 5.0
Table 6
(a)
Based on results from table 6 , plot a graph of precipitate heights against volumes of M nitrate solution added.
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Form 4 Score A+ Module
(b)
What is the volume of M nitrate solution that reacted completely with 5.0 cm3 of potassium chromate (VI) solution? Explain your answer. ……………….………………………………………………………………………………………
(c)
Calculate the number of moles of potassium chromate (VI) found in the test tube and the number of moles of M ions that reacted completel y with the 5.0 cm3 of potassium chromate (VI) solution.
(d)
Determine the formula of M chromate (VI). ………………….……………………………………………………………………………………..
(e)
Write the ionic equation for the formation of M chromate (VI). ………………….……………………………………………………………………………………. [1 mark]
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Form 4 Score A+ Module
7.
Diagram shows two containers, containing colourless solution labelled A and B.
A
B
You are told that the two colourless solutions are calcium nitrate and magnesium nitrate. You are required to label correctly the name of each solution in the containers. Design an experiment to identify which is calcium nitrate and which is magnesium nitrate solution by using aqueous of ammonia solution as a reagent. Your answer should include the following: (a) Problem statement (b) Hypothesis (c) All variables (d) List of materials and apparatus appar atus (e) Procedure (f) Tabulation of data [17 marks]
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Form 4 Score A+ Module
CHEMISTRY SCORE A+ MODULE FORM 4
SET 5 Manufactured Substances in Industry
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Form 4 Score A+ Module
PAPER 2 : SRUCTURE 1
Ammonia is produced in mass quantities in industry through a process as shown in diagram 1 below. Nitrogen Gas
Catalyst chamber
Ammonia gas
Hydrogen gas
Diagram 1 (a)
State the name of the process for the production producti on of ammonia in industry.
(b)
............................................................................................................................................................... [1 mark] Write an equation for the process stated state d in (a)?
(c)
.............................................................................................................................................................. [1 mark] State the catalyt cata lyt used in this process?
(d)
............................................................................................................................................................... [1 mark] Other than the use of catalyst, cata lyst, state two conditions required for optimum optimum production producti on of ammonia.
(e)
............................................................................................................................................................... [1 mark] Ammonia Ammonia react react with with sulphuric acid to form a fertilizer.Name fertilizer.Name the fertilizer.
(f)
............................................................................................................................................................... [1 mark] The reaction between between ammonia ammonia and carbon dioxide produce urea, CO(NH2)2 and water. (i)
(ii)
(g)
Write the equation for the reaction. ...................................................................................................................................................... [1 mark] Determine the percentage by mass of nitrogen in urea. [Relative atomic mass ; H,1; C,12; N,14; O,16 ]
[2 marks] Aqueous ammonia can be used as a reagent to identify cations. State State the observation when aqueous ammonia is slowly added until excess to a solution containing Cu 2+ ion. ................................................................................................................................................................ ............................................................................................................................................................... [2 marks]
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Form 4 Score A+ Module
2.
Diagram 2 shows a flow chart for the formation of Salt A through Process X and Process Y.
Sulphur
Sulphur dioxide
Process X
Sulphur trioxide
Nitrogen
Hydrogen
Process Y
Diagram 2
(a)
Ammonia
Sulphuric Acid
Salt A
Name (i)
Process X : ....................................................................................................
(ii)
Process Y : .................................................................................................... [2 marks ]
(b)
(i)
(ii)
Write the equation for the formation formati on of sulphur trioxide in Process X .................................................................................................................................................... [1 mark] State the catalyst cata lyst used in Process X ................................................................................................................................................... [1 mark ]
(c)
(i)
Write the equation for the formation formati on of ammonia in Process Y
(ii)
................................................................................................................................................... [1 mark ] State the optimum temperature and pressure for Process Y Temperature:.................................... Pressure:................................................... [1 mark ]
(d)
(i)
(ii)
Name salt A ..................................................................................................................................................... [1 mark ] Write the formula for salt A ..................................................................................................................................................... [ 1 mark]
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Form 4 Score A+ Module
(iii)
Calculate Calculat e the percentage perc entage of nitrogen by mass in salt A . Given relative atomic mass H = 1, 1, N = 14 , O = 16, S = 32
[2 mark ] (e)
State one use of sulphuric acid in everyday life.. .............................................................................................................................................................. [1 mark ]
3
Table 3 shows certain polymers and monomers for a polymerization polymerization process. Monomer
Polymer
Amino acid Starch Ethene Chloroethene
Polychloroethene(PVC) Natural rubber Table 3
(a)
What is meant by polymer?
(b)
................................................................................................................................................................ [ 1 mark ] Complete Table 2 by writing the correct polymer or or monomer for the respective respec tive monomer monomer or polymer. [4 marks]
(c)
Draw the structural struct ural formula for the polymer formed from the polymerization polymeriza tion of ethene.
(d)
Diagram Diagra m 3 shows the structural struct ural formula for the polymer polychloroeth polychloroethene ene or PVC.
[ 1 mark ]
H | C | H
H | C | Cl
H | C | H
H | C | Cl
H | C | H
Diagram 3
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H | C | Cl
Form 4 Score A+ Module
(i)
Draw the structural struct ural for the monomer of polychloroethene. polychlor oethene.
[ 1 mark ] (ii)
(e)
In the system syste m for water supply to homes, PVC pipes are widely used to replace metal pipes. State one advantage of using PVC pipes compared to using metal pipes in terms of their chemical properties.
..................................................................................................................................................... [ 1 mark ] Classify the polymers in Table 3 into natural natura l polymers and synthetic polymers. Natural Natura l polymer
Synthetic polymer
[ 2 marks ] PAPER 2 : ESSAY 4.
(a)
Diagram 4 shows the arrangement of atoms in pure copper and an alloy of copper, brass.
Pure copper
brass
Diagram 4 (i)
Explain why is pure copper softer than its alloy. [3 marks]
(ii)
Explain why the alloy, brass is stronger than pure copper. [3 marks]
(iii)
State the aim of alloying. [3 marks]
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Form 4 Score A+ Module
(b) (i)
Explain why pure aluminium aluminiu m is not suitable suitabl e for building bodies of planes. [2 marks]
(ii)
State the alloy suitable suitabl e for building bodies of planes and give reasons for your answer [4 marks]
(c)
(i)
Malaysia is proud of the products from pewter as souvenirs for tourists. Name the main metal and the foreign metal in pewter. [2 marks]
(ii) Besides hardness, state three advantages adva ntages of the alloy pewter to its pure metal. [ 3 marks] 5.
(a)
(i) (ii)
What is meant by the term ‘polymers’?. Name two examples of synthetic polymers. polymers. For F or each example , state its monomer and one common use.
(b)
(i) (ii)
What is meant by the term ‘composite material’?. Name two examples of composite composit e materials and their respective uses.
[ 7 marks ]
[ 5 marks ] (c)
Diagram 5 shows the waste products products from a factory which which affect affect the quality quality of the environment.
a. amples/uses b. pollution
Sulphur dioxide Factory
Building Toxic waste Diagram 5
Based on diagram 5, describe how the waste products affect the quality of the environment. Your description should include the following aspects: Source of pollutants Process Effect [ 8 marks ]
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Form 4 Score A+ Module
PAPER 3 : STRUCTURE 6.
Diagram 6 shows shows the set up up of apparatus of of an experiment to compare compare hardness hardness of copper and brass. The steps of carrying out the experiment are as follows.
1.A steel ball-bearing ball-bearing is is taped onto a copper of of block . 2. A 1-kg weight is hung at a height of 50 cm above the copper block . 3. The weight is allowed to drop onto the ball bearing.
1 kg weight
Metre ruler
4.The diameter of the dent produced by the ball bearing on the copper block is measured. 5. Steps 1 to 4 are repeated on other parts of the copper block to obtain an average value for the diameter of dents.
Steel ball bearing
6. Experiment is repeated by using brass block to replace copper block.
Copper block
Diagram 6 Table 6 shows the results of the experiment Experiment
1
2
3
Diameter of dent on copper block/ cm
0.5
0.6
0.5
Diameter of dent on brass block/cm
0.3
0.3
0.2
Average diameter/ cm
Table 6 (a)
Based on Table 6, record record the average diameter diameter of of dents dents in the space provided. [3 marks]
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Form 4 Score A+ Module
(b)
Give a statement to describe the operational definition of the hardness based on this experiment. ………………………………..………...…………………………….………………………….…
(c)
………………………………..………...…………………………………………………….…… [3 marks] Complete table below.
Name of variables variabl es (i) Manipulated variable:
Action to be taken (i) The way to manipulate variable:
…………………………………………………
…………………………………………………
………………………………………………… (ii) Responding variable:
………………………………………………… (ii) Way to observe in the responding variable: …………………………………………………
………………………………………………… ………………………………………………… ………………………………………………… (iii) Fixed variable:
(iii) The way to maintain the fixed variable:
.. ………………………………………………
…………………………………………………
…………………………………………………
………………………………………………… [6 marks]
(d)
State the hypothesis for this experiment. ...……………………………...……………………………………………………………………… [3 marks]
(e)
Classify the following materials into pure metals and alloy. Iron, steel, copper, a luminium luminium Duralumin, Bronze, [3 marks]
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Form 4 Score A+ Module
7.
Concrete and reinforced concrete are two types of composite materials. Diagram 7 shows an experiment to investigate the strength of concrete and reinforced concrete. The 10kg weight is dropped from a fixed height.
10 kg weight
.
concrete
clamp
Diagram 7 (a)
What is concrete? ……………………………………………………………………………………………………….
(b)
……………………………………………………………………………………………………..... [3 marks] What is the material used to reinforce reinfor ce concrete? concret e? Why is this material able to strengthen the concrete? …………………………………………………………………………..……………………….…. ………………………………………………………………………….…..……………………..... …………………………………………………………………………….………………………...
(c )
…………………………………………………………………………………………………........ [6 marks] State three uses of reinforced concrete. ………………………………………………………………………..……………………………. ………………………………………………………………………..…………………………..... ………………………………………………………………………….…………………………. [6 marks]
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Form 4 Score A+ Module
(d) State the problem statement for this experiment. experi ment. …………………………………………………………………………………….………………….
(e)
(f)
……………………………………………………………………………………………………..... [3 marks] Based on the experiment above, state (i) the manipulated variable. variabl e.
(ii)
...........………………………………………………………………………………………….. the responding respon ding variable. variabl e.
(iii)
...........…………………………………………………………………………………………. the fixed variable. variab le.
..........………………………………………………………………………………………… [3 marks] What is the operational operationa l definition of strength of the composite material in this experiment.. …………….……………………………………………………………………..……………………
……………………………………………………………….…………………..…………………… [3 marks] (g) A commonly used composite material is photochromic photochr omic glass which is made made by embedding glass with silver chloride. (i)
State two uses of photochromic photochro mic glass. …………………................ …………………..................………………… ..…………………………… …………………………… ………………………...……………… ……...………………
…………………………………..................……………… …………………………………..................………………………………… ………………………...…………… ……...…………… [3 marks] (ii) Describe how silver chloride can be prepared in the laboratory. ……………………….................…………………………… ……………………….................…………………………………………….……… ……………….………………… ………… ………………………................……………………… ………………………................…………………………………………… ……………………..………………… ..………………… ……………………………................………………………………………………………… [3 marks]
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Form 4 Score A+ Module
PAPER 3: ESSAY
Kitchen utensils such as pan, pots, spoons and forks rust easily if they are made from iron. To overcome the problem of rusting, kitchen utensils are made from steel.
8.
Referring to the explanation explanation above, plan a laboratory laboratory experiment experiment to compare the rusting of iron and steel. steel. Your experiment should cove the following items: (a) (b) (c) (d) (e) (f)
Statement of problem Variables Hypotheses List of materials materials and apparatus Experimental Experimental procedure Tabulation Tabulat ion of data
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