Module Perfect Score 2009 Chemistry

BAHAGIAN PENGURUSAN SEKOLAH BERASRAMA PENUH DAN SEKOLAH KLUSTER

MODUL PERFECT SCORE  2009

CHEMISTRY

   

Chemistry Perfect Score Module 2009

Set 1 Set 2 Set 3 Set 4

1

CHEMISTRY PERFECT SCORE MODULE 2009 CONTENT

 

1



Guidelines & Anwering Techniques

   

Format of an instrument of chemistry Construct requirement Guidelines for answering paper 1 Guidelines for answering paper 2 Guidelines for answering paper 3 The common command words in paper 2 and 3 The common diagram



2

Set 1

3

Set 2

The structure of Atom  Chemical Formulae and equations  Periodic Table of Elements  Chemical Bonds

 

Electrochemistry Oxidation and Reduction



4

Set 3

5

Set 4

Acids and Bases Salts  Rate of reaction  Thermochemistry 



Carbon compounds Manufactured Substance in Industry  Chemicals for Consumers 

Question Validation Panel • • • • •

Pn En Pn Pn Pn

Wan Noor Afifah Bt Wan Yusoff (SBPI Gombak) Che Malek Bin Mamat (SBPI Batu Rakit) Foo Koi Hoon (SMS Seri Puteri) Faridah Bt Hamat (SMS Seremban) Masodiah Bt Mahfodz (SMS Hulu Selangor)

Question Construction Panel 1 2 3 4 5 6 7 8 9 10 11

En Che Ramli bin Che Ismail En Che Malik bin Mamat Pn Sa’adah binti Mohayuddin En Jong Kak Ying Pn Foo Koi Hoon En Muhammad Arif bin Sawiran Pn Aishah Peong binti Abdullah Pn Lim Ai Lee@Lim Irene Pn Wan Noor Afifah binti Wan Yusoff Pn Norini binti Jaafar En Ooi Yoong Seang

Chemistry Perfect Score Module 2009

SMSTFP SBPI BR SMSSP SMS Kuching SSSP SMSAS SBPIT SMSS Selangor  SBPI Gombak SAS SMS Muar 

2

CHEMISTRY PERFECT SCORE MODULE

GUIDELINES &

ANSWERING TECHNIQUES

CHEMISTRY SPM

Chemistry Perfect Score Module 2009

3

GUIDELINES AND ANSWERING TECHNIQUES FOR SPM CHEMISTRY PAPER 1.0

FORMAT OF AN INSTRUMENT OF CHEMISTRY BEGINNING SPM 2003

No 1

Item Type of instrument Type of item

Paper 1 (4541/1) Objective test Objective it

Number of question

50 (answers all)

Duration of time

1 hour 15 minutes

2

3 5 2.0

4.0

Paper 3 (4541/3) Written Practical Test Subjective Item : Structured Item Extended Response Item: (Planning an experiment)

Structured Item : 1/2 items (answer all) Extended Response Item : 1 item 1 hour 30 minutes

2 hour 30 minutes

CONSTRUCT REQUIREMENT Construct Knowledge Understanding Application Analysis Synthesizing Science process Total mark

3.0

Paper 2 (4541/2) Subjective test Section A : Structured Item Section B : Essay restricted response Item Section C : Essay extended response Item Section A : 6 (answer all) Section B : 2 (choose one) Section C : 2 (choose one)

Paper 1 20 m ( No 1- 20) 15 m ( No 21 – 35) 15 m ( No 36 – 50) 50

Paper 2 14 21 29 21 15 100

Paper 3 50 50

TIPS TO SCORE “ A “ CHEMISTRY 3.1

Master 1. 2. 3. 4.

the topics that contains the basic concepts of chemistry : The structure of the atom Chemical Formulae And Equations Periodic Table Chemical Bond

3.2

Familiarize with different types of questions as listed below and complete the previous SPM papers : 1. Objectives questions (MCQ) (Paper 1) 2. Structured questions ( Paper 2 & 3) 3. Essays (Paper 2) 4. Planning an experiment ( Paper 3) 5. Draw and label the diagram 6. Writing chemical equation( equation( balanced equation, equation, ionic ionic equation, equation, half equation)

3.3

Try to get : 40 marks above for paper 1  60 marks above for paper 2  40 marks above for paper 3

(Total = 140/2 =70 -1A)

GUIDELINE FOR ANSWERING PAPER 1 4.1

Paper 1 questions test students on 1. Knowledge ( Number 1 – 20) 2. Understanding ( Number 21 – 35) 3. Application ( Number Number 36 – 50 )

4.2

Score in paper 1 Indicates student’s level of understanding in chemistry: Less than 20 – very weak 20 – 25 - weak 26 – 30 - average 31 – 39 - good 40 – 45 - very good 46 – 50 - excellent.

4.3

Answer all SPM objective question ( 2003 – 2008). Objective questions for each year contain all topics. If  your score in paper 1 is 40 and above, you will able to answ er questions in paper 2 & 3 easi ly.

Chemistry Perfect Score Module 2009

4

5.0

6.0

GUIDELINE FOR ANSWERING PAPER 2 ( STRUCTURE AND ESSAY) 5.1

Paper 2 questions test student on 1. Knowledge 2. understanding 3. analyzing 4. synthesizing .

5.2

Steps taken are: 1. Underline the command word and marks allocated for each question. 2. Match the command word to the mark allocated for each question. 1 point is awarded 1 mark. 3. Follow the needs of the question ( Refer to the command words, page ……. ) 4. Unnecessary repetition of the statement in the question is not required.

5.3

Three types of questions which involve experiments in paper 2 : I. Type 1 Describe an experiment on…………………Include on…………………Include a labeled diagram in your answer  1. Diagram 2. Procedure 3. Observation/example/data/calculation/equation/sketch of graph/conclusion graph/conclusion II. Type 2 Describe an experiment……………( The diagram will support your answer.) 1. No m ark is allocated for a diagram 2. Procedures 3. Observation/example/calculation/equation/sketch of graph/conclusion III. Type 3 Describe a chemical/confirmatory test for ……. 1. Procedure 2. Observation 3. Conclusion

GUIDELINE FOR ANSWERING PAPER 3 6.1

Structure Question 1/2 Test The Mastery of 11 Scientific Skills 1. Observing 2. Classifying 3. Inferring 4. Measuring (burette , stopwatch, thermometer, voltmeter) 5. Predicting 6. Communicating( e.g construct table and draw graph) 7. Space-Time Relationship 8. Interpreting Data 9. Defining Operationally 10. Controlling Variables 11. Hypothesizing Each answer is allocated mark as follows: 3 marks/2 marks/1 mark/0

6.2

Score : 11 X 3 = 33

Question 3 (essay) Test The Mastery of Planning Experiment . Planning should include the following aspects : 1. Aim of of the the experiment/Statement of the problem 2. All the variables 3. Statement of the hypothesis 4. List of substances/material and apparatus – should should be separated 5. Procedure of the experiment 6. Tabulation of data

• • •

• •

Score : (5 X 3) + 2 = 17

The question normally starts with certain situation related to daily life. Problem statement/ aim of th e experiment / hypothesis and variable can be concluded from the situation given. State all the variables Manipulated variable : − − Responding variable : − Constant variable : list down all the fixed variables to ensure the outcome of the responding variable is related only to the ma nipulated variables. Separate the substances and apparatus Procedure : All the steps taken in the procedure procedure must include the apparatus apparatus used, quantity and type of  − substance ( powder, solution, lumps … etc).

Chemistry Perfect Score Module 2009

5

−

•

7.0

No mark is allocated for the diagram. The complete labeled diagram can help students in : I. Writing the steps taken in the procedure II. Listing the apparatus and materials

Tabulation of data: − The number of columns and rows i n the table is related to the manipulated and responding variables Units must be written for all the titles in each row and column of the table − DO NOT WRITE the observation/inference/conclusion in the table. −

THE COMMON COMMAND WORDS IN PAPER 2 & PAPER 3 CHEMISTRY • • •

The question normally starts with a command word. Students must know the meaning of t he command word to make sure t hat the answer given is according to the question’s requirement. Match the command word to the m ark allocated for each question.

Command word Name/State the name (paper 2 & 3) State (paper 2 & 3)

State the observation (Paper 2 & 3)

Explain (Paper 2 & 3)

What is meant by.. (Definition) (Paper 2 & 3)

Describe chemical test (Paper 2 & 3)

Describe gas test. (Paper 2 & 3)

Explanation/example Give the name , not the formula. Example: Name the main element added to copper t o form bronze. Wrong answer : Sn. Correct answer : Tin Give brief answer only. Explanation is not required. Example : State one substance which can conduct electricity in solid state. Answer : Copper  Write what is observed physically . Example 1 : State one observation when magnesium magnesium powder is added to hydrochloric hydrochloric acid. [ 1 mark] Wrong answer  : Hydrogen gas is released. released Correct answer : answer : Gas bubbles are released Indicate the change of colour , give the initial and final colour of t he substance/chemical. Example 2 : What is the colour change of copper(II) suphate solution. [ 2 marks] Wrong answer : The solution becomes colourless Correct answer : answer : The blue colour of of the solution becomes colourless Give the answer with reasons to explain certain statement statement / fact / observation/ principal. Example 1 : Explain why bronze is harder than pure copper [4 marks] Correct answer : answer : Copper atoms in pure copper are all of the same size and ...........1 they are arranged in layers that can slide easily when force is applied .......... 1 The presence of tin atoms in bronze that are different in size disturb the orderly arrangement of atoms in bronze. ..........1 This reduces the layer of atoms from sliding. .........1 Give the exact meaning Example: What is meant by hydrocarbon. Wrong answer: A compound that contains carbon and hydrogen Correct answer : A compound that contains carbon hydrogen hydrogen only State the method to conduct the test , observation and conclusion. Example : Describe how to identify the ion present in the solution . 3  Answer :  Answer : - Pour in 2 cm of the solution in a test tube. Add a few drops of s odium hydroxide solution and the test tube is shake the test tube - A reddish brown precipitate formed. 3+ - Fe ions present State the method to conduct the test observation and conclusion. conclusion. Example: Describe the confirmatory test for gas released at the anode(oxygen). Wrong answer : Test with a glowing glowing wooden splinter. splinter. Correct answer: - Place a glowing wooden splinter to the mouth of the test tube - The glowing wooden splinter is lighted up - Oxygen gas is released -

Describe an experiment ( 8 - 10 marks) marks) (Paper 2)

-

Plan an experiment ( 17 marks) ( Paper 3)

[ 3 marks] .........1 .........1 ………1 [ 3 marks] …….1 ……1 …….1

No mark is awarded for the diagram. The diagram can help students write the steps taken in the procedure. List of materials 1m Can be obtained from the diagram List of apparatus 1m Procedure - ( 5 – 8 m) Observation/tabulation of data/ calculation/sketch of the graph/ chemical equation /ionic equation /conclusion …… etc. Any additional details relevant derived from the question.

Answer the question according the requirement : Problem statement/Aim of experiment − Hyphotesis − Variables −

Chemistry Perfect Score Module 2009

6

List of substances and apparatus − Procedure − − Tabulation of data Note: For question 3, unlike PEKA report report students only need to answer according to what is stated in the question. - No mark for the diagram. diagram. Diagram can help student student writing the steps taken in the procedure. Describe the process … Describe the structure …. Describe and write equation… Describe how … (Paper 2 & 3) Predict (Paper 2 & 3) Compare (Paper 2) Differentiate (Paper 2) Draw a labeled diagram of the apparatus (Paper 2)

Draw a diagram to show the bonding formed in the compound (Paper 2)

Draw graph (Paper 3)

Draw the energy level diagram ( Paper 2) Draw the arrangement of  particles in solid, liquid and gas. (Paper 2) Draw the direction of  electron flow (Paper 2 /3) Write chemical equation (Paper 2 & 3)

Calculate (Paper 2 & 3) Classify (Paper 3)

Give relevant details derived from the the question.

Make a prediction for for something that might happen based on facts Example: Example: Experiment 1 is repeated using a larger beaker.Predict the increase in temperature Answer : The increase in temperature is lower than experiment 1. 1. Give the similarities and differences between two items/ situations Give differences between two items/situations Example : State three differences between ionic and co valent compound. Answer : State three properties of ionic compound and three properties covalent compound Draw a complete set up of apparatus (i) Functional set up of apparatus (ii) Complete label (iii) Shade solid, liquid and gas correctly. (iv) Draw an arrow and label ’ heat’ if the experiment involves heating (i)Ionic compound – The number of electrons in each shell is correct, 2 electrons in the first shell and 8 electrons in the second and third shell.  – Show the charge of each particle.  – Write the symbol of each element at the centre of the ion. (ii) Covalent compound The number of electrons in each shell is correct, 2 electrons in the first shell and − 8 electrons in the second and t hird shell. − The number of atoms sharing pair of electrons is correct. − Write the symbol of each element at the center of each atom in the molecule. Draw graph as follows : Label the two axis with the correct unit − − Choose suitable scale, the size of the graph graph should be at least ¾ of the size of the graph graph paper. − Plot all the points correctly − Smooth graph ( curve or straight line ) − For the determination of of the rate of reaction (i) Draw a tangent at the curve. (ii) Draw a triangle at the tangent Calculate the gradient of the tangent Draw an arrow for the vertical vertical axis only and label with energy energy . − Draw two horizontal lines for t he reactants and products −

− − −

Solid : Draw at least three layers of particles closely packed in orderly manner and the are not overlap. Liquid : The particles packed closely but not in orderly manner  Gas : The particles are very far apart from from each each other  Draw the direction for the flow flow of electrons on the circiut, not not through the solution.

− −

− − −

Write the balanced chemical equation Differentiate : (i) Balanced chemical equation (ii) Ionic equation (iii) Half equation for oxidation (iv) Half equation for reduction Show all the steps taken Give final answer with unit. Draw table to represent the classification.

Chemistry Perfect Score Module 2009

7

8.0

THE COMMON DIAGRAM IN CHEMISTRY SPM SYLLABUS Labelled Diagram for the Setup of Apparatus/ Apparatus/ Structural Formula

The Structure Of  Atom Determination of  melting and boiling point of naphthalene Determination Melting Point

Determination of Freezing Point

Particle arrangement in solid , liquid and gas

Solid

Liquid

Gas

Chemical Formulae and Equations Determination of  empirical formula

Magnesiu m oxide

Copper(II) oxide

Reaction between sodium/potassium with oxygen Periodic Table

Chemical Bond The electron arrangement in ionic and covalent compound. * Make sure you can explain the formation of the bonds accurately

Reactions between chlorine gas and iron .

Chemistry Perfect Score Module 2009

8

Sodium chloride

Tetrachlorometha ne

Magnesium chloride

Carbon dioxide

Electrochemistry

Molten Lead (II )bromide

Copper(II) sulphate solution (Copper electrode)

Electrolysis

Sulphuric Acid , Potassium sulphate Hydrochloric acid ( gas bubbles released )

Electroplating Electroplating an iron key

Purifying an impure metal

Chemistry Perfect Score Module 2009

9

Voltaic cell

Simple cell

Daniell cell (porous pot)

Daniell cell (Salt bridge bridge )

1.Heating of copper(II) carbonate and confirmator y test for carbon dioxide

ACID ,BASE & SALT 1. Heating of  carbonate compound and confirmatory test for carbon dioxide

2. Preparation of soluble salt (Method I) – Sodium nitrate

2. Preparation of  soluble salt (Method I & II) 3. Preparation of  insoluble salt

3.Preparation of soluble salt (Method II) – Copper(II) sulphate

4. Preparation of insoluble salt – Lead(II) iodide

Chemistry Perfect Score Module 2009

10

Manufactured Substances in industry

H

CH3

C =

C

H H Propene H

Polymerisation

Chloroethane

Alloys Arrangement of  atoms in a metal and an alloy

Polypropene Cl

H

Cl

H

C─ C─C─

C─ C

H

H

H

H

H

Polivinly chloride (PVC)

Arrangement of atoms in a pure metal

Arrangement of atoms in alloy(Bronze )

Rate of reaction Gas is collected using water displacement for carbon dioxide gas, oxygen and hydrogen

Redox 1.Usage of tube U , oxidising agent : a. Chlorine Water  b. Bromine Water  c. Potassium manganate (VII) acidified Reduction agent a.KI b.KBr  c.FeSO4 * Mark the positive and negative terminal 2.Rusting of iron

Iron Diagram to show the rusting of iron

Chemistry Perfect Score Module 2009

11

Thermochemistry

Determination of  Heat Combustion

Carbon Compound

Alcohol Dehydration

Oxidation of alcohol and esterification through reflux

Alcohol Dehydration

Chemistry Perfect Score Module 2009

Oxidation of alcoholand esterification through reflux

12

CHEMISTRY PERFECT SCORE MODULE

SET

1. 2. 3. 4.



The Structure of Atom Chemical Formulae and Equations Periodic Table of Elements Chemical Bonds

Chemistry Perfect Score Module 2009

13

PAPER 2 – STRUCTURE 1

SECTION A o Graph 1 shows the cooling curve of molten naphthalene beginning from 90 C. Tem Tem erat eratur ure/ e/◦C ◦C

90

T

P

R

0

t1

t2

t3

Time/min

Table 1 Based on Table 1, answer answer the following question. (a) State the melting point of naphthalene. …………………………………………………………………………………………………………………………… [1 mark] (b) State the time when all the liquid naphthalene has frozen . …………………………………………………………………………………………………………………………. [1 mark] (c) Why does the temperature of naphthalen e remains constant from t1 to t2? …………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………….. [2 marks] (d) (i) What is the the type of particles particles in naphthalene? naphthalene? …………………………………………………………………………………………………………………………… [1 mark] (ii) Draw the arrangement of particles of naphthalene at point P and R in the space provided.

Point P

Point R [2 marks]

(e) State the physical state of naphthalene during the time (i)

t1 to t2: ……………………………………………………………………………………………………….

(ii)

t2 to t3: …………………………………………………………………………………………………….. [2 marks] (f) When solid naphthalene is heated with direct flame and the physical state of naphthalene changes from solid to gas. Name the process that occurs. ……………………………………………………………………………………………………………………….

Chemistry Perfect Score Module 2009

14

[1 mark] 2

Table 2 shows four substances and their respective formulae Substance

Chemical Formula

Bromine

Br 2

Nickel

Ni

Phenol

C6H5OH

Sodium chloride

NaCl

Table 2 (a) State all substance s that exist as molecules. ………………………………………………………………………………………………………………….. [1 mark] (b) Which substance is an electrolyte? …………………………………………………………………………………………………………………… [1 mark] (c) What is the physical state of bromine at room temperature? …………………………………………………………………………………………………………………… [1 mark] (d) State the substance that can conduct electricit y in solid state ………………………………………………………………………………………………………………… [1 mark] (e) Draw the arrangement of the particles in the substance in (d) at room temperature.

[1 mark] (f)Name the partic les present in sodium chlor ide. ……………………………………………………………………………………………………………………… [1 mark] (g) Graph 2 shows the temperature against time when solid phenol is heated. Tem Tem erat eratur ure/ e/◦◦ C S Q

T1 T0

R

P Time/s

Graph 2 (i) State the melting point of phenol. ………………………………………………………………………………………………………………………. [1 mark] (ii) Explain why there is no change in temperature from Q to R. ………………………………………………………………………………………………………………………. ………………………………………………………………………………………………………………………. [2 mark] (iii) State how the movement of naphthalen e particles changes between R and S during the heating. ……………………………………………………………………………………………………………………….. [1 mark]

Chemistry Perfect Score Module 2009

15

3

Diagram 3 shows the set -up apparatus of an experiment to determine the empirical formula of copper  (II) oxide. Copper(II) oxide Hydrogen gas Porcelain dish

Heat

Anhydrous calcium chloride, CaCl2 Diagram 3 (a)

What is the meaning of chemical formula?

(b)

.........………….………………………………………………………………………………......... [1 mark ] State one precaution that must be taken before the copper (II) oxide is heated.

(c)

………….……...……………………………………………………………….......………………………. [1 mark ] Table 3 shows the results of an experiment carried out by a student. Mass of combustion tube + porcelain dish Mass of combustion tube + porcelain dish + copper (II) oxide Mass of combustion tube + porcelain dish + copper Table 3 (i) Calculate the number of moles of copper in this reaction. [Relative atomic mass : Cu = 64]

30.24g 32.26g 31.86g

[1 mark ] (ii)

Calculate the number of moles of oxygen in this reaction. [Relative atomic mass : O = 16]

(iii)

Determine the empirical formula of copper (II) oxide.

[1 mark ]

(d)

[2 marks] marks] Name another metal oxide that uses the same method to determine the empirical formula. ……..…………………………………………………………………………………….………… [1 mark ]

(e)

M is a reactive metal. State how to determine the empirical formula of the oxide of M. ........................................................................................................................................... [1 mark ]

Chemistry Perfect Score Module 2009

16

4

Diagram 4 shows the apparatus set-up to determine the empirical formula of oxide metal metal M. M oxide

Dry hydrogen gas

Asbestos paper  DIAGRAM 4 (a)

(i)

Name two chemicals used to prepare hydrogen gas in the laboratory. ................................................................................................................................... [2 marks] marks]

(ii)

Write a chemical equation for the reaction in (a)(i). …………………………………………………………………………….………………... [1 mark ]

(b)

Table 2 shows the result of the experiment: Mass of combustion tube + asbestos paper Mass of combustion tube + asbestos paper + M oxide before heating Mass of combustion tube + asbestos paper + product after heating (i)

Determine the empirical formula of M oxide. [Relative atomic mass of O=16, M=55]

(ii)

Write a chemical equation for the reduction of M oxide by hydrogen gas.

39.25 g 47.95 g 44.75 g

[3 marks] marks]

................................................................................................................................... [1 mark ] (c)

State one precaution that must be taken when carrying out the experiment. ............................................................................................................................................

(d)

[1 mark ] Can the empirical formula of magnesium oxide be determined by the same method? Explain your  answer. ............................................................................................................................................ ............................................................................................................................................ [2 marks] marks]

Chemistry Perfect Score Module 2009

17

5

Diagram 5 shows the set-up of apparatus for an experiment to determine the empirical formula of magnesium oxide. Lid Magnesium ribbon

Crucible

Diagram 5 Result: Mass of crucible + lid Mass of crucible + lid + magnesium magnesium ribbon Mass of crucible + lid + magnesium oxide

= 24.0 g = 26.4 g = 28.0 g

(a) What is meant meant by empirical formula? ................................................................................................................................... [1 mark] (b) Based on the above result, (i) calculate the mass of magnesium and the mass of oxygen that have reacted.

[1 mark] (ii)

calculate the mole ratio of magnesium atoms to oxygen atoms. [Relative Atomic Mass: O=16; Mg=24]

[1 mark]

(iii)

determine the empirical formula of magnesium oxide.

[1 mark] (iv)

write the chemical equation for the reaction in the experiment.

[1 mark] (c) Why was the crucible lid opened once in a while during the experiment? ................................................................................................................................... [1 mark] (d) Metal X is placed below hydrogen in the reactivity series. You are required to carry out an experiment to determine the empirical formula of the oxide of metal X. The apparatus provided are combustion tube, glass tube, cork, Bunsen burner, and porcelain dish. (i) Draw a labelled diagram of of the apparatus set-up for the experiment.

[2 marks]

Chemistry Perfect Score Module 2009

18

(e) Describe the steps that should be taken to ensure that all the air in the combustion tube has been expelled. ............................................................................................................................................................................. ............................................................................................................................................................................ .............................................................................................................................................................................. [3 marks] 6

Diagram 6 shows the symbols for atom of element X, Y, and Z.

X

 Y

Z

Diagram 6 (a)

(i) Write the electron arrangement of atom X. ………………………………………………………………………………...… [1 mark] (ii) State the period and the group for element X in the Periodic Table. Period : ….…………………………………… ….…………………………………………………………….. ……………………….. Group : ………………………………………………….……….......... [2 marks]

(b)

(i) What is the proton number of element Z? ....................................................................................................................................................... [1 mark] (ii) Atom of element Y has a nucleon number of 35. Calculate the number of neutrons in atom Z. …………………………………………………………………………………………………. [1 mark] (iii) Write the th e standard representation of element Z ....................................................................................................................................................... [1 mark]

(b)

Element Y and Z are located in the same Group in the periodic table of element. Compare reactivity of element Y and Z. Explain your answer  ………………………………………………………………………………………………………........................... …………………………………………………………………………………………………………………………… …………………………………………………………………………………..................................................... [4 marks]

(c)

Element X can react with sodium to form a compound (i)Name the type of bond in the compound formed between atoms X and sodium. …………………………………………………………………………………...................................................... [1 mark]

Chemistry Perfect Score Module 2009

19

(ii) Give one physical property of the compound in (c)(i). …………………………………………………………………………………......................................................... [1 mark] (d)

Element X can also react with carbon to form a compound. Draw the electron arrangement for the compound formed. [ Proton number of C = 11 ]

[2 marks] 7

Table 7 shows the proton numbers of elements X, Y and Z. Elements

Proton Number 

X Y Z

12 8 6

a)

Table 7 Write the electron arrangement for atom X

b)

………………………………………………………………………………………………………………… [1 mark] X and Y react to form a compound i)

What type type of bond holds holds atom X and Y together? together?

……………………………………………………………………….……………………………………….. [1 mark] ii)

What will happen to atom X during the formation of the compound with atom Y? Explain why. ……………………………………………………………………….................................................. ………………………………………………………………………...................................................

…………………………………………………………………………………………………………… [2 marks] iii) Draw the electron arrangement of the compound formed in in (b)(ii)

[2 marks] iv) State one physical property of the compound formed ……………………………………………………………................................................................ [1 mark]

Chemistry Perfect Score Module 2009

20

c)

Z can react with Y to form a compound. i)

What is the molecular formula of the compound formed? …………………………..................................................................................................... [1 mark]

ii)

What is the relative molecular mass of the compound in c(i). [ Given that relative atomic mass Z = 12; Y= 16] …………………………………………………………………………………………………….. [1 mark]

iii)

Name another compound that has the same physical properties as the compound formed. …………………………………………………………………………..................................... [1 mark]

8

Diagram 8 shows the position of several elements P, Q, R, S, T, U and W.

P Q

T

R

S

V

U W

X

Diagram 8 Using the symbols P, Q, R, S, T, U and W, answer the following questions. (a) State one metal metal and one non- metal Metal:….…………………….…… Non-metal:………………………. [1 marks] (b) Write the electron arrangement of atom V. ..………………………………………………………………………………………………………………………. [1 mark] (c) Which of the elements elements has the biggest atomic atomic radius? ……………………………….………………………………………………………………………………………… [1 mark] (d) (i) Compare the electronegativity of elements Q, T, V and U. ………………………………………..…………………………………………………………………………… [1 mark] (ii) Explain your answer in (d)(i). ……………………………………………………………………………............................................……… ……………………………………………………………………………………............................................. ……………………………………………………………………………............................................……… …………………………………………………………………………………….......................................... [4marks]

Chemistry Perfect Score Module 2009

21

(e) State the ion formed by Q. ..…………………………………………………….………………….……………………………………………… [1 mark] (f) (i) Which element is chemically inert? …....…………………………………………………………………..…………………………………………….…. [1 mark] (ii) Explain your your answer. …....…………………………………………………………………..……………………………………………… [1 mark] (g) Write an equation for the reaction between R and U. …....…………………………………………………………………..…………………………………………………. [1 mark] (h) Give one special characteristi c of S. ……….………………………………………………………………..…………………………………………………. [1 mark] 9

Diagram 9 shows the chemical symbols which represent element P, Q, R and S. 23 11 (a)

(i)

P

16 8

Q

14 6

R

35 17

S

Diagram 9 Write the electron arrangement of atom Q. ………………………………………………………………………………...……………………

(ii)

[1 mark ]

State the period and the group for element Q in the Periodic Table. Period : ….………………………………… ….…………………………………………………………….. ………………………….. Group : ……………………………………… ………………………………………………….………........... ………….………........... [2 marks] marks]

(b)

Atoms of P and Q can react to form a compound. (i)

Name the type of bond in the compound formed between atoms P and Q. ………………………………………………………………………………………………………

(ii)

(c)

[1 mark ]

Draw the electron arrangement for the compound formed.

[2 mark ] Atoms of R and S can also react to form a compound. Draw the electron arrangement for the compound formed.

[ 2 marks] marks]

Chemistry Perfect Score Module 2009

22

(d)

Compare one physical property of compound formed (b) and (c). Explain your answer. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………[4 marks]

10

Table 10 shows the melting point, boiling point and electrical conductivit y of substances P, Q, R, R, and T .

Substance P Q R T

o

Melting point ( C)

o

Electrical conductivity

Boiling point ( C ) Solid

Molten

805

1460

No

Yes

1549

2950

Yes

Yes

-210

-153

No

No

-7

59

No

No

Table 10 (a) Which of the substances is a metal ? ……………………………………………………………………………………………………………………….. [1 mark] (b) (i) State the type of particle in substance P ? …………………………………………………………………………………………………………………………. [1 mark] (ii) Explain why substance P cannot conduct electricity in solid form but can conduct electricity in molten state. ............................................................................................................................................................. ............................................................................................................................................................. [2 marks] (c) (i) What is the physical state of R and T at room temperature ? R : ............................................ T : ....... .................... ................. [2 marks] (ii) Draw the arrangement of particles in substance T at room temperature .

[2 marks] (iii) Explain why the melting and boiling points of substance R and T is low ?

………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………….. [2 mark]

Chemistry Perfect Score Module 2009

23

PAPER 2 ESSAY SECTION B 11 (a) Diagram 11.1 shows two isotopes of an element X 35 17

37

X

17

X

Diagram 11.1

(i) State the number of neutron in each isotope

[ 2 marks]

(ii) State two similarities and two differences between the isotopes [4 marks] (b) Diagram 11.2 shows an atom of element P. The letter used is not the actual symbol of the element. \

X

6p + 6n

Diagram 11.2 . (i) Describe the atom shown in Diagram11.2 (ii)

[4 marks] Another atom of element P has 7 neutrons. Compare Compare this atom with the atom in Diagram 11.2 [4 marks] o

o

(c) X is a substance which melts at 71 C and boils at 314 C o (i) Sketch a graph of temperature against time when molten X at 100 C is cooled to

o

60 C. [2 marks]

o

(ii) Based on the graph in (c)(i), state the physical state of substance X at 71 C and explain the changes in terms of the kinetic energy and the arrangement of particles [4 marks] 12 3

1 mole of any gas occupies 24 dm at room condition. (a)

Explain why 16 g of oxygen occupies the same volume as 22 g of carbon dioxide at room condition. [ 4 marks ]

(b) Caffeine is one of the substance s in coffee. 0.97 g of caffeine consists of 0.48 g carbon, 0.05  –1 g hydrogen, 0.28 g nitrogen and 0.16 g oxygen. The molar mass of caffeine is 194 g mol . Based on the information above, Determine the empirical formula and molecular formula of caffeine. [8 marks] marks] (c) Fertilisers usually have a high content of nitrogen. Nitrogen is needed to increase the growth of  plants such as vegetables. The following substances are the examples of fertiliser which are used by farmers . ♦ Ammonium suplhate, (NH4)2SO4 ♦ Urea, CO(NH2)2 ♦ Hydrazine, N2H2 Calculate the percentage of nitrogen by mass in each of the three fertilizers given above and hence determine the best fertiliser a farmer should used for his plants.

Chemistry Perfect Score Module 2009

24

[ 8 marks ]

13. (a) Diagram 13.1 shows the standard representat ion for sodium element

Diagram 13.1 State three information that can be deduced from the diagram Draw the atomic structure of sodium atom . [6 marks]

Chemistry Perfect Score Module 2009

25

(b) Diagram 13.2 shows the empirical formula of glucose :

Diagram 13.1 (i) What is the meaning of empirical formula ? (ii) The relative molecular mass of glucose is 180, determine the molecular  formula of glucose [4 marks] (c) (i)

A chloride of iron contains 2.80 g of iron and 5.32 g of chlorine. Determine Determine the empirical formula of the compound. [ Relative atomic mass : Fe = 56 , Cl Cl = 35.5 ] [4 marks]

(ii) Write a chemical equation equation to represent represent the reaction reaction between iron iron and chlorine. Calculate the volume of chlorine gas that reacts completely with 2.80 g iron. 3 [ 1 mole of gas occupied 24 dm at room temperature and pressure ] [6 marks] 14

(a) What is meant by empirical formula? [1 mark ] (b) A carbon compound contains 92.3% of carbon and 7.7% of hydrogen by mass. The relative molecular mass of this compound compound is 78. Find the molecu lar formula of this compound. [Relative atomic mass: C=12; H=1] (c) Describe how you could determine the empirical empirical formula of magnesium oxide in the laboratory. Your description should include • procedure of experiment • tabulation of result • calculation of the results obtained [Relative atomic mass: O=16; Mg=24]

[5 marks] marks]

[11 marks] marks]

(d) Magnesium can reduce reduce copper oxide oxide to copper. Explain why the empirical formula of the copper oxide cannot be determined by heating the mixture of  copper oxide and magnesium powder. [2 marks] marks]

Chemistry Perfect Score Module 2009

26

PAPER 2 ESSAY SECTION C 15 (a) Diagram 15 shows the electron arrangement of a compound formed from the reaction between element Y and element Z These letters are not the a ctual symbols of the elements.

+

Y

Z

Diagram 15 (i) Based on diagram 15 , write the electron arrangement for atoms of element Y and Z. Explain the position of element Y in the Periodic Table of the Elements. [6 marks ] (ii) Element Y can react with sodium and sodium hydroxide to form compounds. Write the chemical equation to represent the reaction . [4 marks ] (b) Table 15 shows the proton number for atoms P , Q and R. These letters are not the actual symbols of the elements. Elements

Proton number 

P Q R

11 17 6 Table 15

Using the information information in table 15, explain how two compounds can be formed from these elements . The two compounds should have different bond types. [10 marks ]

Chemistry Perfect Score Module 2009

27

PAPER 3 STRUCTURE 16 An experiment is conducted to find out the freezing point of liquid naphthalene. A boiling tube containing molten naphthalene at 95 ° C is allowed to cool in a conical flask to room temperature. The temperature of naphthalene is recorded at half-minute intervals. Diagram 1 shows the reading of the thermometer for this experiment.

95

90

90

90

90

85

85

85

85

80

80

80

Initial temperature

Temperature at

Temperature at

Temperature at

0 s : ………

30 s : ………

60 s : ………

90 s : ………

85

85

85

85

80

80

80

75

75

75

70

Temperature at

Temperature at

Temperature at

Temperature at

120 s : ………

150 s : ………

180 s : ………

210 s : ………

Diagram 16 (a) Record the temperature in the spaces provided in Diagram 16. [3 marks] (b) Construct a table to record the data shown in Diagram 16.

[3 marks] (c)

(i)

Draw a graph of temperature against time. [3 marks]

(ii)

On your graph , mark the freezing point of naphthalen e.. e.. [3 marks]

Chemistry Perfect Score Module 2009

28

(d)

(i)

What is meant by freezing point ? ………………………………………………………………………………………………………………

(ii)

[3 marks] th th Explain why the temperature of naphthalen e remains constant form 90 seconds to 150 seconds during the cooling process.

……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………. [3 marks] (e) Why is the boiling tube placed in the conical flask during the cooling process ? ……………………………………………………………………………………………………………………. …………………………………………………………………………………………………………………… [3 marks]

Chemistry Perfect Score Module 2009

29

(f) Diagram shows the arrangement of particles of four substances. Na Na

Na

Na

Na

Na

Na

Na

Na

+

-

Na

Cl

-

Na

Cl

+

+

Na -

-

Cl

+

Cl

Na

Cl Cl

O O

Na

Na

Na

Na

+

Na

-

Cl

P

+

Na

-

Cl

Q

H

O

Cl Cl

Cl Cl

H O

Cl Cl

R

H

H

S

Classify P, Q , R, and S into element and compound. Element

Compound

[ 3 marks ]

17

A student carried out an experiment to determine the empirical formula of magnesium oxide. The step and set-up of apparatus of the experiment are shown in Diagram 17.

Step 1. Crucible and lid are weighed

Set-up of apparatus

2. Crucible, lid and magnesium ribbon are weighed

3. Magnesium and ribbons heated until the reaction is complete

4. Crucible, lid and magnesium oxide are weighed when cold

Diagram 17

Chemistry Perfect Score Module 2009

30

(a) Complete the following table by stating the observations and related inferences in the experiment. Observation

Inferences

(i)

(i)

(ii)

(ii)

[6 marks] (b) Record the reading to two decimal places for  The mass of crucible and lid :…………….g The mass of crucible, lid and magnesium ribbon: …………. g The mass of crucible, lid and magnesium oxide when cold: ………… g [3 marks] (c) (i) What is is the mass of magnesium that has been used?

(ii) What is the mass of oxygen which reacted with magnesium?

(iii) Determine the empirical formula of magnesium oxide. Use the information that the relative atomic mass, Mg = 24 and O = 16

[3 marks] (d) Based on your answer in (c)(iii), how many moles of magnesium and oxygen atoms have reacted?

[3 marks]

Chemistry Perfect Score Module 2009

31

18

Elements in Group 1 of the Periodic Table of Elements can be arranged based on the reactivity of the elements with water. An experiment is carried out to investigate the statement above. Table 18 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 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 18 (a) State the variables that are involved in the experiment. Name of variables Action to be taken (i) Manipulated variable: (i) The way to manipulate variable: ……………………………………..

………………………………………..

……………………………………..

………………………………………...

(ii) Responding variable:

(ii) What to observe in the responding variable: ………………………………………..

…………………………………… ………………………………………..……… …………………………………… (iii) Controlled variable:

(iii) The way to maintain the controlled variable:

……………………………………..

………………………………………

……………………………………..

……………………………………… [6 marks]

(b)

State one hypothes is for the experiment. ……………………………………………………………………………………… ………………………………………………………………………………………

Chemistry Perfect Score Module 2009

[3 marks] marks]

32

(c)

Based on the observations in the figure above, arrange lithium, potassium and sodium in the descending order of reactivity of metals towards water.

Descending order of reactivity of metals towards water. [3 marks] marks] (d)

Solution X was produced from the reaction of sodium with water. Classify the ions that exist in solution X into positive ions and negative ions. Positive Ions

Negative Ions

[3 marks] marks]

19 “When lithium metal is put into water, it moves moves very slowly on the surface of the water. When sodium metal is put into water, it moves quite fast and produces “hiss” sound. When potassium metal is put into water, it moves very fast and produces small explosion”. Metal

Water 

Plan an experiment in the laboratory to investigate the reactivity of lithium, sodium and potassium with water  and describe the effect of the solution produced towards a red litmus paper. The planning of your experiment must consist of the following: (a) Aim of experiment (b) Statement of the hypothesis (c) All the variables (d) List of substances and apparatus (e) Procedure of the experiment (f) Tabulation of data [17 marks]

Chemistry Perfect Score Module 2009

33

CHEMISTRY PERFECT SCORE MODULE



SET 

1. Electrochemistry 2. Oxidation and Reduction

Chemistry Perfect Score Module 2009

34

1

-3

Diagram 1 shows the set-up of apparatus to investigate the electrolysis electrolysis of 1.0 mol dm of sodium sulphate solution using carbon electrodes.

Carbon electrode Y

Carbon electrode X

-

sodium sulphate 1.0 mol dm

solution

A Diagram 1 (a)

i) W hat is meant by anion? anion ? .............................................................................................................................................................. [1 mark] ii) State all the anions present in the electrolyte.

(b)

.............................................................................................................................................................. [1 mark] What is the energy change that occurs in the above process? ............................................................................................................................................................. [1 mark]

(c)

(d)

Write the formulae of the ions which move to the electrode X. ……………………................................................................................................................................. [1 mark] i) State the name of the gas collected in the test tube at the electrode X ............................................................................................................................................................. [1 mark] ii) Write the half equation for the the reaction at the electrode electrode X ……………………………………………………………………................................................................. [1 mark] iii) Describe the chemical test to confirm the gas in (d) (i)

.

............................................................................................................................................................ ........................................................................................................................................................... [2 marks] (e)

If the sodium sulphate solution is replaced by the copper(II) sulphate solution in the above electrolysis, i) what is the observation at the electrode X ……………………………..……………………………………………………………………………….. [1 mark] ii) Explain your answer in (e) (i). ……………….…………………………………………………………………………………………….... ……………………………………………………………………………………………………………….. [2 marks]

Chemistry Perfect Score Module 2009

35

2

Diagram 2 shows the set up of apparatus of a chemical cell.

Copper 

Magnesium

Copper(II) nitrate solution

Magnesium nitrate solution

Salt bridge Diagram 2 (a) Mark the direction of the flow of electrons in the above diagram.

[1 mark]

(b) (i) What is is the function of the the salt bridge? ……………….………………………………………………………………………………………………….. [1 mark] (ii) Suggest a suitable chemical substance to be used as salt bridge. ………………………….……………………………………………………………………………………….. [1 mark] (c) State the energy change in the cell above. …………………………………………………………………………………………………….………………. [1 mark] (d) i) State the negative terminal ……….……………………………………………………………………………...................................... [1 mark] ii) Explain your answer in d(i). …….…………………………...…………………………………………................................................. [1 mark] (e) i)

ii)

(f) i)

ii)

State one observation at the copper electrode.

…………………..………………………………………………………………………………………....... [1 mark] Write the half equation for the reaction in (e) (i). ………………………….………………………………………………………………………………...... [1 mark] Voltage value of the cell is 2.7 V. If the the magnesium is replaced by zinc, predict the voltage value produced. …………….....……………………………………………………………………………………………. [1 mark] Explain your answer. ………… …………………………………………………………………........................................ ………….………………………………………………………………………………………………. [1 mark]

Chemistry Perfect Score Module 2009

36

3

Diagram 3 shows the set-up of the apparatus to study the reactions that take place in test tubes X and Y. Chlorine water 

Bromine water 

Iron (II) sulphate solution

Sodium bromide solution

X

Y

Diagram 3 (a)

State the observation for the reaction i)

in the test tube X

ii)

…….……………………………….………………………………………………………………………. [1 mark] in the test tube Y ……………………………………………………………………………………………………………….. [1 mark]

(b)

Write the ionic equation for the reaction in (a)(ii)

(c)

…………………………..…………………………………………………………………………………. [2 marks] State what is meant by an oxidising agent in terms of electron transfer.

(d)

…………………………………………………………………………………………………………….. [1 mark] Referring to the reaction that takes place in the test tube X, i)

what is the change in the oxidation number of bromine ?

ii)

……………………………………………………………………………………………………………. [1 mark] state the name of the reducing agent. ……………………………….………………………………………………………………………….. [1 mark] Referring to the reaction that takes place in test tube Y,

(e) i)

state the substance that is oxidised.

ii)

…………………………………….……………………………………………………………………. [1 mark] write the half equation to represent the reaction that occurred in (e)(i).

…………………………………………………………………………………………………………. [1 mark] iii) what is function of chlorine water? ………………………………..……………………………………………………………………….. [1 mark] iv) State the name of another reagent that can replace chlorine water. ………………………………..……………………………………………………………………… [1 mark]

Chemistry Perfect Score Module 2009

37

4

Table 4 shows the observation of an experiment to study the reactivity of metals X , Y and Z with oxygen. Metal powders of X , Y and Z are heated vigorously in a flow of oxygen. Potassium manganate(VII) powder is used as the source of oxygen.

Metal powder  and colour  X

Brown

Y Z

Observation While heating

after heating

Glows faintly

Black powder 

Grey

Burns vigorously with bright flame

White powder 

Grey

Burns fairly bright Yellow powder 

White powder 

Table 4 (a) State the name of one of one compound that can be used to substitute potassium manganate(VII) in this experiment. …………………………………………………………………………………………………………………. [1 mark] (b) (i) State the type of reaction undergone by the metal powders? …………………………………………………………………………………………………………… [1 mark] (ii) Give a reason for your answer in (b)(i). …………………..………………………………………………………………………………………. [1 mark] (c) Suggest the name of metal Z. ………………………………………………………………………………………..……………………… [1 mark] (d) Based on the observation in table 1 , arrange the reactivity of metal X , Y and Z in ascending order. ………………………………………………………………………………………………………………. [1 mark] (e) Draw a labelled diagram of the set-up of apparatus for this experiment.

[2 marks] (f) 4.8 g of metal metal Y reacts reacts with oxygen to produce produce 8.0 g of oxide Y. Y. Calculate the empirical formula of oxide Y. [Relative atomic mass: O=16 ; Y = 24]

[3 marks]

Chemistry Perfect Score Module 2009

38

Essay (Section B) 5

(a) Copper (II) sulphate solution is electrolyse d using carbon electrodes. What is produced at the cathode. Write a half equation for the reaction occurred . [2 marks] (b) Diagram 5 shows the set-up of apparatus to study whether substance X is an electrolyte or non- electrolyte .

Carbon electrode Substance X

DIAGRAM 5 Table 5.1 shows substance X and their observation . Substance X

Observation

Solid sodium chloride

Bulb does not light up

Sodium chloride aqueous solution

Bulb lights up

Solid naphthalene

Bulb does not light up Table 5.1

(i)

Explain the observation for each substance .

(ii)

[6 marks]

Classify substance X into electrolyte and non-electrol yte. [1 mark]

(b)

Concentration Concentration of electrolyte affects the product of electrolysis at the electrode. By using sodium chloride solution, explain briefly how to prove that statement. In your  explanation, write the chemical equation involved. [6 marks]

(c)

Table 5.2 shows the result of experiment for displacement reaction between substanc e P, Q and R with salt solution of P, salt solution of Q and salt solution of R. Salt solution of P

Salt solution of Q

Salt solution of R

X X

√ X

√ √ -

P Q R

√

: reaction occur 

X

: No change Table 5.2

Arrange metal P, Q and R in ascending order of electropositivity. Explain your answer. [4 marks]

Chemistry Perfect Score Module 2009

39

6

Table 6 shows the observation of two experiment to study the effect of metal P and metal Q on the rusting of iron. Rusting of iron is a redox reaction. Experiment

After 1 day

I

II

Observation Large amount of dark blue precipitate

No dark blue precipitate. Solution turns pink.

Table 6 (a)

By using a chemical equation , explain what is meant by redox reaction in term term of electron transfer. [3 marks]

(b)

Explain why there is a difference in observation in experiment I and experiment II. Arrange in descending order metals P, iron and Q based on the electropositivity of the metals. [8 marks]

(c)

With the aid of a suitable diagram, describe the rusting process of iron. [7 marks]

(d)

Explain why the rusting of iron at coastal area is faster. [2 marks]

Essay (Section C) 7

a) Explain why potassium iodide can conduct electricity in the molten state but cannot do so in the solid state. [2 marks] b) Diagram 7 shows two types of cells.

Silver  electrodes

Silver  electrode

Zinc electrode

Silver nitrate solution Cell B

Cell A Diagram 7

Compare and contrast cells A and B. Include in your answer the observations and half equations for  the reactions at the electrodes in both cells. [8 marks]

Chemistry Perfect Score Module 2009

40

c) A student intends to purify an impure copper plate. Design an experiment to purify the copper plat. Your answer should consist of the following: • Chemical required • Procedures of the experiment • Labelled diagram showing the set up of apparatus • Half equation involved in the reaction • Observations [10 marks] 8

(a) The equation shows a redox reaction. M is a metal. X(s) + CuSO4 (aq) XSO4 (aq) + Cu(s) Suggest metal X and explain the redox reaction in terms of the transfer of electrons . [6 marks] (b) By using a suitable example and the chemical equation, explain why the neutralization reaction is not a redox reaction. [4 marks] (c) Table 8 shows some examples of oxidizing agents and reducing agents.

Oxidising agent

Reducing agent

Acidify potassium manganat(VII) solution, KMnO4

Iron(II) Sulphate solution, FeSO4

Acidify potassium dichromate(VI) solution, K2Cr 2O7

Potassium iodide solution, KI

Chlorine water  Cl2

Potassium bromide KBr 

Bromine water  Br 2

Hydrogen peroxide H2O2 Table 8

The electric current is produced by the transfer of electron at a distance from a reducing agent to an oxidizing agent in a chemical reaction

By using any oxidizing agent and reducing agent given, describe an experiment to prove the statement above. Your description must include the following; o o o o

set up of the apparatus procedure of the experiment observations ionic equations [10 marks]

Chemistry Perfect Score Module 2009

41

Paper 3 9

Diagram 9 shows the set-up of apparatus for an experiment to construct the electrochemical series by measuring the potential difference produced by a simple voltaic cell.

Copper 

Metal P

-3

Copper(II) sulphate 1.0 mol dm solution Diagram 9

The experiment is repeated by substituting metal P with Q and R. Diagram 9 shows the reading of the voltmeter when different pairs of metals are used. For each of the voltaic cell, copper acts as a positive terminal.

1.0 0.5

1.5

2.0

V

0

1.0 2.5

0.5

3.0

0

Copper / P

1.5

2.0

V

2.5 3.0

Copper / Q

1.0 0.5

1.5

2.0

V

2.5 3.0

0

Copper / R Diagram 9

a)

State the potential difference and the negative terminal by completing Table 9 Metal pairs

Potential difference / V

Negative terminal

Copper/ Metal P Copper/ Metal Q Copper/ Metal R [3 marks] Table 9 (b)

State the hypothesis of the experiment. experiment. ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… [3 marks]

Chemistry Perfect Score Module 2009

42

(c)

Based on the experiment, complete the following table: Manipulated variable:

Method to manipulate the variable:

…………………………………………

………………………………………..

………………………………………...

………………………………………..

………………………………………… Responding variable:

……………………………………….. How the variable is responding:

…………………………………………

………………………………………..

…………………………………………

………………………………………...

…………………………………………

………………………………………..

Controlled variable:

Method to maintain the controlled variable:

………………………………………….

…………………………………………

…………………………………………

…………………………………………

…………………………………………

………………………………………… [6 marks]

(d)

Based on Table 5, arrange copper, metal P, Q and R according to the descending order of  electropositivity. ……….. ……………………………………………………………………………………………………..…… [3 marks]

10

A student carries out an experiment to investigate the oxidation and reduction in electrolytic cell. Copper(II) sulphate solution is electrolysed using copper electrodes for 30 minutes.

Diagram 10 shows the set-up of apparatus for the electrolysis of copper(II) sulphate solution using copper electrodes. Beginning of experiment

After 30 minutes

A

A

Copper electrodes

Blue solution

Copper(II) sulphate solution

Diagram 10

Chemistry Perfect Score Module 2009

Blue solution

43

(a)

Write the observations at the anode ,cathode and copper(II)sul phate solution.. Observations Anode Cathode Copper(II)sulphate solution [3 marks]

(b)

Based on the observations , what inferences can be made? Inference Anode Cathode Copper(II)sulphate solution [3 marks]

(c)

Write the half-equation to represent the oxidation and reduction that occurres at cathode and anode.

Oxidation : .................................................................................................................................... Reduction : ................................................................................................................................... [3 marks] (d)

State the operational definition for the reaction that takes place at the anode ...................................................................................................................................................... ...................................................................................................................................................... [3 marks]

(e)

Predict the product formed at anode, if copper electrode in this experiment is replaced with carbon electrode. …………………………………………………………………………………………..……………….… ……………………………………………………………………………………………..………………. [3 marks]

(f)

Classify all positive and negative ions that are found in the copper(II) sulphate solution. . ..................................................................................................................................................... . .................................................................................................................................................... [3 marks]

Chemistry Perfect Score Module 2009

44

11

The further the distance between two metals in the electrochemical series, the bigger is the potential difference.

You are given the copper strip, lead strip, iron strip, zinc strip, aluminium strip, and magnesium strip . By referring to the statement above, plan a laboratory experiment to construct 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

12

[17 marks]

Metal X is more electropositive than iron. Metal Y is less electropositive than iron.

Referring to the above statements, plan a laboratory experiment to investigate the effect of rusting of  iron when in contact with metal X and metal Y. Your planning should include the following aspects: (a) Problem statement (b) All the variables (c) Hypothesis (d) List of materials and apparatus (e) Experimental procedure (f) Tabulation of data [17 marks]

Chemistry Perfect Score Module 2009

45

CHEMISTRY PERFECT SCORE MODULE

SET 

1. 2. 3. 4.



Acids and Bases Salts Rate od reaction Thermochemistry

Chemistry Perfect Score Module 2009

46

1

-3

An experiment is carried out to investigate neutralization reaction between 1.0 moldm of sulphuric acid 3 and 25 cm of sodium hydroxide. A few drops of phenolphthalein are added to the solution. The acid is added slowly to the flask until end point. The result of the experiment is shown in table 1.

3

Initial reading of burette ( cm ) 3

Final reading of burette ( cm )

1

2

3

17.30

17.00

17.70

39.70

39.20

39.70

3

Volume of acid used ( cm ) Table 1

a) What is meant by end point? point? ………….…………………………………………………………………………………………………………….. [1 mark] b) State the change of colour of phenolphtha lein during titration. ………..…………………………………………………………………………………………………………… [1 mark] c)

Fill in the table table by calculating calculating the volume volume of sulphuric acid used in the experiment. experiment. [1 mark]

d) Write chemical equation of the reaction in this experiment. …………….……………………………………………………………………………………………………… [1 mark] e) (i) Calculate the average average volume of sulphuric acid used in the reaction.

[1 mark] (ii) Calculate the number of mol sulphuric acid used in the reaction

[1 mark] f)

Draw a labeled diagram to show the the set up of apparatus apparatus used used in the experiment. experiment.

[2 marks]

Chemistry Perfect Score Module 2009

47

g) State two precautions that should be taken during the experiment …….…………………………………………………………………………………………………………

……..…….…………………………………………………………………………………………………… [2 marks]

2

An experiment is carried out to determine the concentration of sulphuric acid by titration. A few drops of  3  –3 methyl orange indicator is added to 20.00 cm of 0.1 mol dm potassium hydroxide solution solution in a conical flask. Sulphuric acid of unknown concentration is then added. The results obtained are shown in the table 2. Titration 3 Volume of acid added / cm Colour of the mixture

I 5.00

II 10.00 Yellow

III 15.00 Orange

IV 20.00 Red

V 25.00

Table 2 (a)

What is the colour of methyl orange (i) in an acidic solution? .......…………………………………………………………………………………………………….............. [1 mark] (ii) in an alkaline solution? …………………………………………………………………………………………………………………… [1 mark] (iii) in a neutral solution?

(b)

(c)

……………….………………………………………………………………………………………………….. [1 mark] 3  –3 What is the volume of sulphuric acid that completely neutralises 20.00 cm of 0.1 mol dm sodium hydroxide solution? …..……………………………………………………………………………………………………………… [1 mark] Write (i) a chemical equation for the reaction. ……..……………………………………………………………………………………………………………. [1 mark] (ii) an ionic equation for the reaction.

(d)

………………………………………………………………………………………………………………….. [1 mark] Calculate the molarity of sulphuric acid.

[1mark]

Chemistry Perfect Score Module 2009

48

(e)

What is the colour of the mixture when a total of  3 (i) 5.00 cm of acid is added? ……………………………………………………………………………………………………………… [1 mark] 3 (ii) 25.00 cm of acid is added? …..….…………………………………………………………………………………………………..……… [1 mark]

(f)

-3

3

What is the expected volume of 0.1 moldm hydrochloric acid that neutralises completely 20 cm of   –3 0.1 mol dm potassium hydroxide solution? ……...………….…………………………………………………………………………………………………… [1 mark]

3

Diagram 3 below shows laboratory activities in preparation of a salt. Excess zinc oxide powder  3

50 cm of  -3 2 mol dm nitric acid

Heat

Heat Diagram 3 (a) Name the type of reaction in the preparation of salt.

…………………..………………………………………………………………………………………………….. [1 mark] (b) Explain why zinc carbonate powder is added in excess. ………………..…………………………………………………………………………………………………….. . [1 mark] (c) Write a chemical equation for the reaction that occurs inside the beaker. …………………..………………………………………………………………………………………………….. [1 mark] (d) Draw the apparatus set-up used to separate the excess zinc carbonate powder from the mixture in the diagram above.

[2 marks] (e) Calculate the maximum mass of the salt formed. [Relative atomic mass: N=14, O=16, Zn=65]

[2 marks]

Chemistry Perfect Score Module 2009

49

(f) Suggest two substances substances that can replace zinc oxide oxide in the experiment experiment to obtain the the same type of salt. salt. ………………….………………………………………………………………………………………………… [2 marks] 4

3

-3

6.0 cm of 0.5 mol dm silver nitrate solution is poured into 6 different test tubes. Different volume of 1.0 -3 mol dm sodium chloride solution are added to each test tube. The mixture is shaken and the height of  precipitate formed in each test tube is measured and recorded as shown in the table 4. Test tube -3 Volume of 0.5 mol dm silver  3 nitrate solution (cm ) -3 Volume of 1.0 mol dm 3 sodium chloride solution (cm ) Height of precipitate (cm)

1

2

3

4

5

6

6.0

6.0

6.0

6.0

6.0

6.0

1.0

2.0

3.0

4.0

5.0

6.0

0.5

1.0

1.5

1.5

1.5

……..

Table 4

(a) State the name of the precipitate formed. ………………….…………………………………………………………………………………………………….. [1 mark] (b) What is the colour colour of the precipitate? precipitate? ……………….……………………………………………………………………………………………………….. [1 mark] 3 (c) What is the volume of sodium chloride needed to completely react with 6.0 cm silver nitrate solution? ………………..………………………………………………………………………………………………………. . [1 mark] (d) Calculate (i) the number of moles of silver nitrate in the reaction.

(ii)

[1 mark] the number of moles of sodium chloride that has completely reacted with 1 mole of silver  nitrate.

[2 marks] (e) Write the ionic equation for the formation of the precipitate. ………………….…………………………………………………………………………………………………….. [1 mark] (f) Predict the height of the precipitate formed in test tube 6. ……………………………………………………………………………………………………………………… ….. [1 mark]

Chemistry Perfect Score Module 2009

50

-3

-3

(g) The concentration of sodium chloride solution is changed from 1.0 mol dm to 2.0 mol dm and the other conditions remain the same. Sketch the graph of height of precipitate against the volume of  sodium chloride solution.

[2 marks] 4

Diagram 5 shows a series of reactions for copper(II) oxide and its other compounds.

Copper(II) oxide

heat

Solution W

Dilute sodium hydroxide solution

Lead(II) nitrate solution

Precipitate Y

Solution Z

Precipitate X

Dark blue solution Diagram 5

(a)(i)

(ii)

Name the solution W. ………………….………………………….…….……………………………………………………… [1 mark] Describe briefly how to prepare a sample of dry salt from solution W. ………………….……………………….…………………………………………………………………… ……………… ……………………….……………………………………………………………………… …………………………………………..……………………………………………………………………

(b)(i)

………………….………………………..……………………………………………………………… [3 marks] What do you observe when dilute sodium hydroxide solution is added drop by drop until in excess into solution W? …………………..……………………..……………………………………………………………………. ………………..…………………..…..…………………………………………………………………… [2 marks]

(ii)

Write down the formula of precipitate X. …………………………………………………………………………………………………………………. [1 mark]

Chemistry Perfect Score Module 2009

51

(c) Solution Z is added into solution W until no changes are observed. A dark blue solution is formed. Name the solution Z. …………………………………….……………………………………………………………………………… [1 mark] (d) When solution W is added into lead(II) nitrate solution in a test tube, tube, precipitate Y and copper(II) nitrate solution are formed. (i) What is the colour of precipitate Y?

(ii)

………………….………………………………………………………………………………………… [1 mark] Write down the ionic equation to show the formation of precipitate Y.

(iii)

….………….……………………..……………………………………………………………………… [1 mark] How can you separate precipitate Y from copper(II) nitrate solution? ……………….……………………..……………………………………………………………………… [1 mark]

6

3

An experiment was conducted to study the effect of temperature on the rate of reaction between 50 cm -3 3 -3 of sodium thiosulphate solution 0.2 mol dm and 5 cm of sulphuric acid 1.0 mol dm to form a yellow precipitate. Diagram 6 shows the set-up of apparatus for the experiment.

3

50 cm of sodium thiosulphate -3 3 solution 0.2 mol dm + 5 cm of  -3 sulphuric acid 1 mol dm

Diagram 6 The experiment was repeated five times using different temperatures. Table 1 shows the temperature and time taken for mark ‘X’ to disappear from view. Experiment 1 2 3 4 5

o

Temperature/ C 28.0 40.0 50.0 60.0 70.0 Table 1

(a)

Draw a graph of temperature against time for this experiment.

(b)

From the graph, calculate the rate of reaction in (i) Experiment 2

Time/s 55 33 23 17 13

[3 marks]

(ii) Experiment 4

[2 marks]

Chemistry Perfect Score Module 2009

52

Chemistry Perfect Score Module 2009

53

(c) Compare the rate of reaction between Experiment 2 and Experiment 4. Explain your answer by using the Collision Theory. ………….………………………………………………………………………………………………… …………………….……………………………………………………………………………………… ……………………………….…………………………………………………………………………… ………………………………………….………………………………………………………………… ……………………………………………………..……………………………………………………… [5 marks] (d) Write the chemical equation for the reaction. ………………….……………………………………………………………………………………………… [1 mark] (e) Name the yellow precipitate formed. ……………..…………………………………………………………………………………………………… [1 mark] (f) State one other factor that can affect the rate of reaction for this experiment. ……………..……………………………………………………………………………………………………. [1 mark]

7

Three experiments were conducted to study the rate of reaction between hydrochloric acid and zinc. 3 Table 7 shows the the mixture of the substances used and time taken to collect 25 cm of gas released in each experiment. Expeiment I II III

Mixture of substance s used 3 -3 20.0 cm hydrochloric acid 1.0 mol dm + 2.0 g zinc 3 -3 20.0 cm hydrochloric acid 1.0 mol dm + 2.0 g zinc + 5 drops of copper(II) sulphate sulphate solution 3 -3 20.0 cm sulphuric acid1.0 mol dm + 2.0 g zinc Table 7

Time/s 50.0 32.0 25.0

(a) Draw the set-up of apparatus used in this experiment.

[2 marks] (b) Calculate the average rate of reaction in Experiment II.

[1 mark] (c) Write the ionic equation for the reaction. …………….…………………………………………………………………………………………………….. [1 mark]

Chemistry Perfect Score Module 2009

54

(d) Compare the rate of reaction between Experiment I and II. Explain your answer by using the Collision Theory. ……………….………………………………………………………………………………………………….. ……………………………….………………………………………………………………………………….. ……………………………………………….………………………………………………………………….. ……………………………………………………………….………………………………………………….. [4 marks] (e) Compare the rate of reaction between Experiment I and III. Explain your answer by using the Collision Theory. …………………..……………………………………………………………………………………………… ………………….…………………………………………………………………………………………….. ………………….…………………………………………………………………………………………… ………………….…………………………………………………………………………………………… [4 marks] (f) (i) State the name of the gas collected in the experiments. ……………..…………………………………………………………………………………………………. [1 mark] (ii) Describe one test to confirm the gas collected in (f)(i). ………………….……………………………………………………………………………………………….

8

……………….…………………………………………………………………………………………………. [2 marks] An experiment is carried out to determine heat of displacement for the reaction between copper and 3 silver nitrate solution. In this experiment, excess copper powder is added to 50 cm of silver nitrate -3 -1 solution 0.5 mol dm . The heat of displacement in this experiment was -105 kJ mol . -1 0 -1 Specific heat heat capacity of the solution solution is 4.2 J g C (a)

What is meant by heat of displacement ?

………………………………………………………………………………………………………………. [1 mark] (b) State another observation besides the change in temperature.

(c)

…….…………………………………………………………………………………………………..……….. [1mark] Based on the information from this experiment, calculate (i) the number of moles of silver ions reacted.

[1 mark] (ii) the amount of heat released.

[1 mark] (iii) the change in temperature.

[2 marks]

Chemistry Perfect Score Module 2009

55

(d)

State two assumptions made during the calculation s. …………………………………………………………………………………………………………………..

(e)

…….……………………………………………………………………………………………………………. [2 marks] Construct an energy level diagram for the reaction .

[2 marks] (f)

Polystyrene cup A is used in the above experiment . The experiment is repeated using cup B. Predict the change in temperature. Explain your answer.

Polystyrene cup

Prediction:

Cup A

Cup B

….……………………………………………………………………………………………………………. [1 mark] Explanation: …..………………………………………………………………………………………………......................

(g)

......………………………………………………………………………………………………...................... [2 marks] Explain why copper powder used in this experiment is in excess. ......………………………………………………………………………………………………...................... [1 marks]

(h)

If copper powder is replaced with magnesium, predict the change of the magnitude in heat of  reaction obtained. Explain your answer. …..………………………………………………………………………………………………...................... ......………………………………………………………………………………………………...................... [2 marks]

Chemistry Perfect Score Module 2009

56

9 Experiment I is carried out to determine the heat of neutralisation between strong acid and strong alkali. It is -1 found that the heat of neutralisation is –57 kJ mol . The diagram 9 show the energy level diagram for the reaction between strong acid and strong alkali.

Energy +

-

H (aq) + OH (aq)

∆H = -57 kJ mol

-

H2O(l)

Diagram 9 a)

Name an example of strong acid and a strong alkali.

b)

……………………………………………………………………………………………………………………. [1 mark] What is meant by “heat of neutralisat ion” in the experiment? …………………………………………………………………………………………………………………….

c)

……………………………………………………………………………………………………………………. [1 mark] State two information about the reaction which can be obtained from the above energy level diagram. ……………………………………………………………………………………………………………………. …………………………………………………………………………………………………………………….

d)

……………………………………………………………………………………………………………………. [2 marks] In another experiment, experiment II is carried under the same conditions as experiment I, whereby a 3 -3 3 50 cm of 1 mol dm ethanoic acid is added to 50 cm of strong alkali with a concentration of 1 mol -3. 0 dm The temperature of the mixture increased by 6.5 C. (i) Calculate the number of moles of strong alkali used.

(ii)

[1 mark] Calculate the heat of neutralizatio n for the reaction between ethanoic acid and strong alkali -1o -1 -3 [Specific capacity for all solutions is 4.2 Jg C and the density of all solutions is 1.0 g cm ]

[3 marks]

Chemistry Perfect Score Module 2009

57

e)

(i)

Compare the heat of neutralizat ion for Experiment I and Experiment II

(ii)

………………………………………………………………………………………………………… [1 mark] Explain your answer in e(i) ……………………………………………………………………………………………………………… …………………………………………………………………………………………………………….. [2 marks]

f)

3

-3

3

If Experiment II is repeated by adding 100 cm of 1 mol mol dm ethanoic acid to 100 cm strong alkali -3 0 with concentration 1 mol dm , the increase in temperature is still 6.5 C. Explain why. …………………………………………………………………………………………………………………. ………………………………………………………………………………………………………………….. [2 marks] ESSAY SECTION B

10 (a) What is meant by strong acid? [2 marks] 3

-3

(b) Two samples of acids are tested and exhibit the same pH value. One sample is 50 cm 0.5 moldm 3 -3 of suphuric acid while another sample is 50 cm 1.0 moldm of hydrochloric acid. Explain why.

[4 marks] (c)Diagram 10 shows hydrogen chloride gas being prepared in the laboratory by adding concentrated sulphuric acid slowly through a thistle funnel to solid sodium chloride. The gas produce is passed thorough water and methylbenzene

Diagram 10 (i) State the observation s when aqueous hydrogen chloride solution and hydrogen chloride in methylbenzene are added with the following: Universal Indicator  Zinc powder  Copper(II) oxide powder  [6 marks] (ii) Based on your answer in c(i), which of the solution is acidic? Explain your answer. [4 marks]

Chemistry Perfect Score Module 2009

58

(iii) Diagram 10 shows the apparatus used to study whether aqueous hydrogen chloride solution and hydrogen chloride in methylbenze ne are a re an electrolyte or non- electrol yte .

A

A

Carbon electrode

Carbon electrode

aqueous hydrogen chloride solution

hydrogen chloride in methylbenzene

Experiment I

Experiment II Diagram 10

State the observations in experiment I and II. Explain your answer. [4 marks] 11

(a)

You are required to prepare a dry sodium nitrate salt. The chemicals supplied supplied are:

• • •

Dilute nitric acid Sodium hydroxide solution Phenolphthalein

Describe a laboratory activity to prepare the salt. Your answer should include the chemical equation involved. [10 marks] (b)

Decribe briefly how you prepare copper(II) chloride salt solution from the chemical substances provided below.

• • • (c)

Copper(II) Copper(II) sulphate solution Dilute hydrochloric acid Sodium carbonate solution

[6 marks] Potassium carbonate solution is added into lead(II) nitrate solution to produce solid X and potassium nitrate solution. The mixture is shaken, then filtered. Solid X is heated to produce solid P and gas Q. (i) Name solid P and state its colour. [2 marks] (ii) Name gas Q and describe a method to verify its identity. [2 marks]

ESSAY SECTION C 12

(a) Using suitable examples, explain what is meant by (i) diprotic acid (ii) strong acid (b)

(c)

[4 marks] Explain why sodium hydroxide hydroxide solution solution and aqueous aqueous ammonia ammonia of the same same concentration concentration have different pH value. [6 marks] 3 -3 Describe how to prepare 250 cm of 1.0 mol dm potassium hydroxide starting from solid potassium hydroxide . 3 -3 Describe how you would prepare 250 cm of 0.1 mol dm potassium hydroxide from the solution. [ Relative atomic mass : H, 1; O, 16; K, 39]

Chemistry Perfect Score Module 2009

59

[10 marks]

13

(a)

An insoluble salt can be prepared by the precipitation reaction. Give an example of an insoluble salt and suggest two solutions to prepare the insoluble salt. Write the ionic equation to represent the precipitation reaction. [4 marks]

(b)

Figure below shows an incomplete flow chart of cation and anion tests for salt X.

Salt solution of X Cation test

Anion test

2+

SO4

Fe

2-

2+

2-

Use the reagents listed below to confirm that salt solution of X contains Fe ions and SO4 ions. REAGENTS • Sodium hydroxide solution • Ammonia solution • Hydrochloric acid • Barium chloride solution

[6 marks]

(c) Magnesium sulphat e is soluble salt. Describe how to prepare a dry sample of magnesium sulphate in the laboratory. Your answer should consist of the following: • Chemicals required • Procedure of the preparation • Chemical equation involved in the reaction [10 marks]

14

(a)

Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

-1

H = - 152 kJmol

(i)

Draw an energy level diagram for the above equation.

(ii)

[2 marks] Explain the differences in energy content of reactants as compared to the products. [2 marks]

(b)

Table below shows the result of neutralizat ion reactions. Experiment I II III

Neutralizatio n reaction NaOH + HCl → NaCl + H2O NaOH + CH3COOH → CH 3COONa + H2O 2NaOH + H2SO4 → Na2SO4 + 2H2O

Heat release (kJ) 57 54 114

Explain why why there are are differences differences in heat released released between; (i)

Experiment I and Experiment II

(ii)

Experiment I and Experiment III

[3 marks] [3 marks]

Chemistry Perfect Score Module 2009

60

(c) 2+

Ca (aq) +

2-

CO3 (aq) 

CaCO3 (s)

-1

H = + 12.6 kJmol

Describe a laboratory experiment to determine the heat of reaction for the above reaction, include the following in your answer: [Relative atomic mass : C=12 ; O=16 : H=1 ] diagram showing the set-up of apparatus o chemicals requires o procedures of the experiment o a table to collect the data o calculation involved o [10 marks] 15

(a)

What is the meaning meaning of the heat combustion of propanol? [2 marks]

(b)

(i)

By using a labeled diagram describe an experiment how to determine the heat of  combustion of the propanol in the laboratory. In your explanation, state together the necessary steps to calculate the heat of combustion of  propanol. [Relative molecular mass of propanol = 60] [14 marks]

(ii)

State the precaution steps that should be taken during this experiment. [2 marks]

(c)

Table 15 shows the value of the heat of combustion for methanol and propanol. Alcohol compounds Methanol Propanol

-1

Heat of combustion/k J mol -723 -2004 Table 15

Compare the heat of combustion of methanol (CH3OH) with the heat of combustion of propanol (C3H7OH). Explain your your answer. [2 marks]

PAPER 3 16

Two experiments are carried out to study the effect of the size of calcium carbonate on the rate of  reaction. 3 -3 Experiment I: 1 g of calcium carbonate chips react with 20.0 cm of 0.2 mol dm hydrochloric acid 3 -3 Experiment II: 1 g of calcium carbonate powder react with 20.0 cm of 0.2 mol dm hydrochloric acid The rate of reaction is determined by measuring the volume of of carbon dioxide gas given off against time using the downward displacement of water method. The volume of gas released is recorded in Table 17.1 and Table 17.2 below. Experiment I Time / s 0 60 120 180 240 300 360 3

Burette reading / cm

50.00

18.00

9.50

8.00

8.00

3

Volume of gas / cm

0.00 Table 16.1

Experiment II Time / s 3

Burette reading / cm

3

Volume of gas / cm

0

60

120

180

240

300

360

50.00

22.00

13.50

9.00

8.00

8.00

8.00

0.00

Chemistry Perfect Score Module 2009

61

Table 16.2 Diagram below shows the burette reading for Experiment I at 60, 120 and 180 seconds.

25

19

14

24

18

13

23

17

12

Burette reading at 60 seconds (a)

(b) (c) (d)

Burette reading at 120 seconds

Burette reading at 180 seconds

Record the burette reading and the volume of gas released at 60, 120 and 180 seconds in Table 16.1. [3 marks] Record the volume of gas released in both experiments in Table 16.1 and Table 16.2. [3 marks] By using the same axes, draw a graph of the volume volume of gas released against time for Experiment I and II. [3 marks] Based on the graph in (c), which experiment has a higher rate of reaction? Explain your answer.

……………………………………………………………………………………… .............……………………………………………… .............…………………………… ……………………. …. ................................. ... [3 marks] (e)

(i) State the variables involved in this experiment. Manipulated variable ……………………………………………………………………………………………………… Responding variable …………………………………………………….………………………………………………… Constant variable ……….……………………………………………………………………………………………… [3 marks] (ii) State the hypothesis for these experiments. ………..…....…………………………………………...…………………………………………… ………. ..…..……………………...…………………………………………………………………

(f)

………….……….…………………………………………………………………………………… [3 marks] Predict the volume of gas released at 420 seconds in Experiment II.

(g)

……………..…………………………………………………………………………………………...… [3 marks] Classify the following reaction into fast reaction and slow reaction. Rusting, Fermentation,

Neutralization, Photosynthes is, Combustion, Combustion, Corrosion, Displacement

Precipitation

[3 marks] 17

3

A student perform an experiment to determine the heat displacement of copper. 50 cm of copper of copper (ll) 3 sulphate solution 0.5 mol dm was poured into a polystyrene cup. Initial temperature temperature of the solution

Chemistry Perfect Score Module 2009

62

was recorded. Then excess zinc powder was added into the copper(II) sulphate solution in the polystyrene cup and stirred as shown in diagram 18.1. thermometer  Copper(II) sulphate solution Polystyrene cup Zinc powder 

Before

After 

Diagram 17.1 The initial temperature and maximum temperature were recorded as in diagram 17.2

30 25

Initial temperature (a)

40 35

maximum temperature

Diagram 17.2 State two observations in this experiment ……………………………………………………….……………………………………………………

(b)

……………………………………………………….…………………………………………………… [3 marks] Refer diagram 17.2, determine the temperature value Initial temperature……………………………………………. Maximum temperature ………………………………………. Temperature difference ………………………………………. [3 marks]

(c)

Calculate the heat change in this experiment. -1 0 -1 -3 (Heat capacity of solution = 4.2 g C ,Density of solution = 1 gcm )

[3 marks] (d)

Give the inference for this reaction ……………………………………………………………….………………………………………… ….………………………………………………………………………………………………………

(e)

…………………………………………………………….…………………………………………… [3 marks] 3 In another experiment , excess zinc powder was poured into 50 cm copper(I l) sulphate solution 3 1mol dm . Predict the change in temperature obtained in this experiment. ……………………………………………………………………………………………………………… [3 marks]

Chemistry Perfect Score Module 2009

63

(f)

Write ionic equation for the reaction in this experiment

…..…………………………………………………………………………..……………………………… [3 marks] Essay Paper 3

19

A company manager was approached by a sales man who tried to convince him octane (petrol) is a better fuel than heptane in terms of the heat released when burnt in excess oxygen .

Design a laboratory experiment to compare the heat of combustion for the above mentioned fuels. Your answer should include the following: (a) Aim of experiment (b) Hypothesis (c) All variables (d) List of materials and apparatus (e) Procedure (f) Tabulation of data [17 marks]

CHEMISTRY PERFECT SCORE MODULE

Chemistry Perfect Score Module 2009

64



SET 

1. 2. 3.

Carbon Compounds Manufactured Substances in Industry Chemicals for Consumers

Chemistry Perfect Score Module 2009

65

1.

Table 1 below shows molecular formulae of four carbon compounds. Compound

Molecular Formula

S

C3H6

T

C4H10

U

C3H7OH

V

C2H5COOH Table 1

(a)

Write the general formula of the homologous series of compound T. ..........................……..…………………………………………………………………………………… [1 mark ]

(b)

(c)

State the functional group of compound S and compound V Compound S

:…………………………………………………………….…………………… :………………………………………… ………………….………………………... …...

Compound V

: ……………………………………… ……………………………………… ……………………………………………. ……. [2 marks] marks]

Compound T shows isomerism. Draw the structural formula of all of all isomers of compound T and give the IUPAC name.

[4 marks] marks] (d)

Compound V and compound U are reacted with the presence of the concentrated sulphuric acid. (i) State the name of the product formed from the reaction. ……………………………………………………….………………………………..…………….. (ii) State the uses of concentrated concentrated sulphuric sulphuric acid. ……………………………………………………….……………………………..………………. (iii) State the special characteristi c of the product

(e)

…………………………………………………………………………………………..…………… [3 marks] marks] Compound U burns in excess oxygen to produce carbon dioxide and water. (i) Write a balanced chemical chemical equation equation for for the reaction. ..................................................................................................................................... [1 mark ] (ii) 11.2 g of compound U burns in excess oxygen, calculate number of carbon dioxide molecules formed. 23 [Relative atomic mass C = 12, O = 16 and Avogadro number = 6.03 x 10 ]

[2 marks] marks]

Chemistry Perfect Score Module 2009

66

2

Diagram 2 shows a series of conversions that involves an alcohol, P which has a molecular formula of  C2H 5 OH. Glucose C6H12O6

Process II Hydrocarbon, R

Alcohol, P C2H5OH

Process I

Carboxylic acid, Q CH3COOH

Diagram 2

(a)

Draw the structural formulae of P and Q.

P:

Q:

[2 marks] (b)

State the name of the substance required for Process I

(c)

…………………………………………………………………………………………………..…… [1 mark] State one observation if an aqueous solution of Q is added to sodium carbonate solution. ……………………………………………………………………………………………………..…… [1 mark] P can react with Q to form an organic compound. (i) Write the chemical equation for the reaction

(d)

(ii)

(e)

(f)

…………………………………………………………………………………………….……… State the name of the compound formed

(i)

…………………………………………………………………………………………………… [2 marks] State the name of Process I.

(iii)

…………………………………………………………………………………………………… Write the chemical equation for this reaction

………………..………………………………………………………………………………… [2 marks] Alcohol, P can be obtained from glucose. (i) State the name of the process involved.

(iii)

……………….………………………………………………………………………………… Write the chemical equation for this process …………….…………………………………………………………………………………… [2 marks]

Chemistry Perfect Score Module 2009

67

3.

Diagram 3 shows the structure of olive oil.

H

H ― C ― OOC(CH 2)7CHCH(CH2)7CH3

H ― C ― OOC(CH 2)7CHCH(CH2)7CH3

H ― C ― OOC(CH 2)7CHCH(CH2)7CH3

H

Diagram 3 (a)

(i)

State the name of the of the homologous series that olive oil belongs to. …………………………………………………………………………………………… [1 mark]

(ii)

Circle on the diagram, the functional group that determines the homologous series for  olive oil. [1 mark]

(iii)

Write down the formulae of the two main components to make olive oil ………………………………………………………………………………………………

(b)

……………………………………………………………………………………………… [2 marks] Is olive oil a saturated or unsaturated compound? Give a reason. ………………………………………………………………………………………………………

(c)

……………………………………………………………………………………………………… [2 marks] Olive oil can be converted into margarine. (i) Name the reactant, catalyst and temperature for the reaction to convert olive oil to margarine. Reactant:………………………………………………………………………..…………… Catalyst:……………………………………………………………………………………… Temperature:……………………………………………………………………………….. (ii)

Name the type of reaction in c(i). ……………………………………………………………………………………………… [4 marks]

Chemistry Perfect Score Module 2009

68

4.

Diagram 4 shows the conversions conversions of organic compound A to another substances,C substances,C2H4Br 2 and C2H5OH through Processes A and C. Reagent B

C2H4Br 2

Process I  Compound A

Process II 

C2H5OH

Steam Diagram 4 (a)

What is meant by organic compound? ……………………………………………………………………………………………............ ………………………………………………………………………………............................. [1 mark]

(b)

(i)

Write the molecular formula of compound A.

(ii)

……………………………………………………………………….............................. [1 mark] State the name of the compound A. ……………………………………………………………………………………............. [1 mark]

(iii)

Identify a functional group of compound A. ……………………………………………………………………….............................. [1 mark]

(c)

Compound A reacts with Reagent B to produce substance C2H4Br 2 through Process I. (i)

Suggest Reagent B.

(ii)

……………………………………………………………………...............................[1 mark] State the name of Process I. ……………………………………………………………………………….……............ [1 mark]

(iv)

State the observation when the reaction occurs. ……………………………………………………………………………………….............. [1 mark]

(d)

Substance C2H5OH is produced when the compound A reacts with steam through Process II. (i)

Write the equation to show the reaction. …………………………………………………………………………………………............ [1 mark]

(ii)

State the homologous series represented by C2H5OH. …………………..………………………………………………………………………............ [1 mark]

(iii)

State one condition to carry out Process II. …………………..………………………………………………………………………............

Chemistry Perfect Score Module 2009

69

[1 mark] 5.

Table 5 below shows four types of industrial products immediately.

Type of industrial product

Example

Glass

S 

Polymer

Polyvinyl chloride, PVC

Alloy

T 

U 

Bricks

Composition Silica, lead(II) oxide Vinyl chloride Copper and tin Silica, aluminium oxide and iron(III) oxide

Table 5 (a)

State the name of the type of industrial product U .

(b)

……………………………………………………………………………………………………………. [1 mark] (i) State the name of the type of glass S .

(c)

(ii)

…………………………………………………………………………………………………….. Give one characteristic characteristic of glass S .

(iii)

…………………………………………………………………………………………………….. Give one use of S  of S .

(i)

…………………………………………………………………………………………………… [3 marks] Draw the structure of the monomer that forms PVC.

(ii)

(d)

PVC is used to make water pipes. Give an advantage of using PVC as water pipes as compared to metal pipes.

(i)

……………………………………………………………………………………………………. [2 marks] Draw the arrangement of atoms of the alloy T .

(ii)

Name the alloy T which T which has the given composition.

(ii)

…………………………………………………………………………………………………… Name one use of the alloy ……………………………………………………………………………………………………. [2 marks]

Chemistry Perfect Score Module 2009

70

6.

The following equation shows a reaction in the preparation of soap.

(Tripalmitin)

(a)

(i)

State the name of the process used to produce soap. ……………………………………………………………………………………………….. [1 mark]

(ii)

Why is sodium chloride added to the reacting mixture during the preparation of the soap? ……………………………………………………………………………………………….. [1 mark]

(iii)

Why the soap is formed rinsed with water?

(iv)

…………………………………………………………………………………………………. [1 mark] A student student wants to prepare prepare a potassium palmitate soap. What alkali alkali should he use?

(v)

…………………………………………………………………………………………………… [1 mark] Draw the structural formula for sodium palmitate in the space provided

[2 marks] (vi)

One of the properties of soaps is that they can form lather with water. What is the function of lather? …………………………………………………………………………………………………… [1 mark]

(b)

Diagram below shows the structural formula of a particle of detergent.

Chemistry Perfect Score Module 2009

71

n (i)

Draw the hydrophobi c and hydrophilic parts of the detergent particle.

Hydrophobic

7.

Hydrophilic

(ii)

The formula mass of the detergent particles is 330. Calculate the value of n. [Given that the relative atomic mass of H = 1, C = 12, O = 16, Na = 23, S = 32]

(iii)

State one advantage of using detergent over soap.

………………………………………………………………………………………………… [5 marks] Table 7 shows the examples and side effects of modern medicine.

Name of medicine Amphetamine Barbiturate Cortisone

a.

Side Effects Cause addiction, suspicious, fearful, aggressive, insomnia and weight loss Cause addiction and death Weight gains, high blood pressure, weak heart, blindness, children’s growth stunted, headache Table 7

State the type of modern medicine in Table 7 i. Amphetamine: ……………………………………… …………………………………………………………………………… ………………………………………… …… ii. Barbiturate: ………………………………… ………………………………………………………………………… …………………………………………………. …………. iii.Cortisone: …………………………………………………………………………………….. [3 marks]

b.

State the function of stimulant.

c.

……………………………………………………………………………………………………………..…… [1 mark] Why psychothe rapeutic drugs cannot be taken without doctor’s prescription? ……………………………………………………………………………………………………………………

d.

………………………………………………………………………………………………………………...… [1 mark] Name two health problems that can be treated using cortisone? ……………………………………………………………………………………………………………………. [2 marks]

Chemistry Perfect Score Module 2009

72

ESSAY SECTION B 8. (a)

Explain briefly what is meant by ‘homologous series’ [5 marks]

(b)

Explain the difference in sootiness for the combustion of the 5 carbon members from the alkane and alkene series. [Relative atomic mass: H = 1, C = 12] [5 marks]

H

H

O

H    C    C    C    O    H H

O

H

H

H    C    O    C    C    H

H

H W

H

Z Diagram 8

(c) Diagram 8 shows the structural formulae of two organic compounds, W and Z. (i) Name W and Z. State the similarities and differences between W and Z in terms of their formulae. (ii) Compare physical properties W and Z in term of solubility and smell. (iii) A compound Y has the molecular formula and chemical properties similar to that of Z. Write the structural formula of Y and give one use of Y. (iv) Write the chemical equation to form Y and name the catalyst for the reaction. [10 marks] 9. Diagram 9 shows the conversions of several organic compounds.

Compound X

Ethanoic acid

Ethyl ethanoate

Ethene Diagram 9 (a) Compound X comprises of 52.2% carbon, 34.8% oxygen and 13% hydrogen with a relative molecular  mass of 46. Determine the molecular formula of compound X and draw its structural formula. [Relative atomic mass: H = 1, C = 12, O = 16] [5 marks] (b) Describe an experiment to prepare ethyl ethanoate [6 marks] (c) What type of reaction is required to change compound X into ethene and what are the conditions required? [3marks] (d) Explain how ethanoic acid can coagulate latex. How can you prevent the coagulation process? [4 marks] (e) Ethene can be converted into a polymer. (i) What is a polymer? (ii) Write the equation equation for this process. process. [2 marks]

Chemistry Perfect Score Module 2009

73

10. (a) Sulphur dioxide, SO2, is one of the by-products of the Contact Process. It can cause environmental pollution like acid rain. Sulphur dioxide gas dissolves in rain water to produce sulphurous acid (i) Write the chemical equation for the reaction between sulphur dioxide gas and rain water. (ii) State three effects of acid rain to the environment. [4 marks] (b) Diagram 10 shows shows an industry preparation preparation of sulphuric acid by the Contact Contact Process.

Stage I S

SO2 Oxygen

Stage III

Stage II SO3 Oxygen

Stage IV X

Concentrated sulphuric acid

H2SO4 Water 

Diagram 10 (i) Name the compound X. (ii) Write the chemical equation of the reaction at stage II. (iii) The chemical equation below shows the reaction between sulphur and oxygen gas at stage I. S + O2  SO2 Given that the relative atomic mass of S = 32, O = 16 and the molar volume of any gas is 24 3 -1 dm mol at room temperature and pressure. Calculate the maximum volume of sulphur dioxide gas produced if 48 g of sulphur is burnt completely in oxygen gas. [6 marks] marks] (c) Brass is an alloy of copper. Pure copper is ductile and malleable whereas brass is stronger and harder  than copper. (i) Explain why pure copper is ductile and malleable? [5 marks] marks] (ii) Name the element which is added to copper to make brass. Explain why brass is strong and harder  than copper. Draw a diagram to show the arrangement of atoms in brass. [5 marks] marks] 11.

(a) Describe how sulphuric acid is produced by the Contact process. Your Your answer should include the equations for all the reactions that take place and the optimum condition required. [10 marks] (b) Production of ammonia in industry is carried out by the Haber process. State the sources of nitrogen and hydrogen gases and the optimum conditions needed to increase the rate of production of ammonia so that a maximum yield is obtained. [6 marks] (c) Explain how the properties of ceramics are useful in the manufacture of motor engines and spacecraft. [4 marks]

Chemistry Perfect Score Module 2009

74

12. 12.

Diagram 12.1 shows the structural formula of soap.

CH3

CH2 CH2

CH2 CH2

CH2 CH2

CH2 CH2

CH2 CH2

CH2 CH2

CH2 CH2

 – 

COO Na

Part X

+

Part Y

Diagram 12.1 (a)

State the name part X and part Y. State the solubilit y of each parts in water and grease. [ 4 marks]

(b)

Diagram 12.2 shows a set-up of apparatus when a student carried out two experiments to investigate the cleansing effect of soap and detergent on oily stained cloth in hard water.

Experiment Experiment I:

Experiment II:

Soap + hard water 

Detergent + hard water 

Arrangement of  apparatus

Cloth with oily stain

Observation

Cloth with oily stain

Oily stain remained

Oily stain disappeared

Diagram 12.2 Compare the cleansing effect between Experiment I and Experiment II. Explain why there are differences in the observations. State the substance which is more suitable as a cleansing agent to remove stain in hard water. [6 marks] (c)

Patient X, Y and Z are suffering from dental pain, pneumonia and depression respectively. What are the medicines that can be used to treat patients X, Y and Z ? [3 marks]

Chemistry Perfect Score Module 2009

75

(d)

Based on your answer in (c ), (i)

(ii)

(iii)

State one precaution that should be followed by patient X while taking the medicine. Explain why. [2 marks] Explain why patient Y must complete the whole course of the medicine prescribes to him even if he feels b etter. [3 marks] State two side effects of the medicine taken by patient Z. [2 marks]

ESSAY SECTION C 13(a) The diagram below shows the release of sulphur dioxide gas from the smokestack of a power station.

Sulphur dioxide is always associated with the cause of acid rain. Describe how the sulphur dioxide affects the quality of environment. Your description should include the following aspects:  Sourc Sources es of sulphu sulphurr dioxi dioxide de  Health Health hazards hazards of sulphur sulphur dioxide dioxide  Formatio Formation n of acid rain and its effects effects [10 marks] marks] (b)

Samuel believes that brass is harder than copper. On the other hand, Kelly thinks otherwise. Based on the above argument, describe a laboratory experiment to show the hardness of brass compared to copper. Explain the results from the experiment. [10 marks] marks]

14. (a) Describe how sulphuric acid is produced by the Contact Contact process. Your answer should include the equations for all the reactions that take place and the optimum conditions required. [10 marks] marks] (b) Production of ammonia in industry is carried out by the Haber process.

State the sources of nitrogen and hydrogen gases and the optimum conditions needed to increase the rate of production of ammonia so that a maximum yield is obtained. [6 marks] marks] (c)

Explain how the properties of ceramics are useful in the manufacture of motor  engines and spacecraft.

Chemistry Perfect Score Module 2009

[4 marks] marks]

76

PAPER 3 15. Diagram 15 shows the apparatus set-up for an experiment to compare the elasticity properties of  vulcanised rubber and unvulcanised rubber.

Cli Rubber strip

Ruler  W ei h t

Diagram 15 An experiment is carried out using weights of 10g, 20g and 30g to get the increase in length of the vulcanised rubber and the unvulcanised rubber. The table below shows the results obtained from the experiment. Types of rubber

Vulcanised rubber 

Unvulcanised rubber 

Weights (g)

10

20

30

10

20

30

Initial length, l1 (cm)

8.0

8.0

8.0

8.0

8.0

8.0

Length after stretching, I2 (cm)

10.0

12.0

11.0

12.0

16.0

20.0

8.5

9.0

9.5

10.0

12.0

14.0

Increase in length, I2 –I1 (cm) Increase in length after weight is removed. (cm) (a)

Complete the table above based on the above experiment. experiment.

[3 marks] marks]

(b) State one hyp othesis for th is experiment. …………………………………………………………………………………………….

(c)

………………………………………………………………………………………….... [3 marks] marks] Based on the information above, complete the following table.

Name of variables (i) Manipulated variable:

Action to be taken (i) The way to manipulate variable:

……………………………………..

………………………………………..

……………………………………..

………………………………………...

(ii) Responding variable:

(ii) What to observe in the responding variable:

……………………………………

………………………………………..

……………………………………

………………………………………..………

(iii) Controlled variable:

(iii) The way to maintain the controlled variable:

……………………………………..

………………………………………

……………………………………..

……………………………………… [6 marks] marks]

Chemistry Perfect Score Module 2009

77

(d)

Based on the experiment above, which rubber strip is more elastic?. Explain your answer. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… [3 marks] marks]

(e)

Give the definition of vulcanised rubber? ……………………………………………………………………………………………………… ………………………………………………………………………………………………………

16.

An experiment was carried out to compare the elasticit y of unvulcanized and vulcanized lengths of the rubber strips were measured as shown in Table 16.

Weight (g) 10 20 30 40 50

Unvulcanized rubber strip Initial Length after removal of  length weight (cm) (cm) 7.0 7.0 7.0 7.0 7.0 7.0 7.0 8.0 8.0 9.0

[3 marks] rubber. The

Vulcanized rubber strip Initial length Length after removal of  (cm) weight (cm) 7.0 7.0 7.0 7.0 7.0

7.0 7.0 7.0 7.0 7.0

Table 16 (a) State the problem statement for this experiment. ……………………………………………………………………………………………………………… . [3 marks] (b) State the variables for this experiment. (i)

Manipulatedvariable:……………………………………………………………………………

(ii) Responding variable: …………………………………… ……………………………………………………………………………. ………………………………………... (iii) Controlled variable ………………………………………………………………………………. [3 marks] (c) State the hypothesis hypothesis for this this experiment. experiment. …………………………………………………………………………………………………………….. [3 marks] (d) Give the the operational definition for this experiment. …………………………………………………………………………………………………………….. [3 marks] (e) State the minimum weight at which each of the rubber strip failed to return to its original length after the removal of the weight. …………………………………………………………………………………………………………….. [3 marks]

Chemistry Perfect Score Module 2009

78

17.

An experiment is carried out as shown in the diagrams.

3

Two beakers A beakers A and B are filled with 200 cm of sea water. A spatula of soap and detergent are added to beakers A beakers A and B respectively and stirred until they dissolve. Two pieces of cloths stained with greasy spots are added to both solutions and stirred for 10 minutes. The cloths are then examined. (a) State the aim of the experiment. …………………………………………………………………………………………....

[3 marks] marks]

(b) State the hypothesis of the experiment. …………………………………………………………………………………………....

[3 marks] marks]

(c) For the experiment, state the (i) manipulated variable: ………………………………………………………………………………………….... (ii)

responding variable: …………………………………………………………………………………………....

(iii)

constant variable: ………………………………………………………………………………………….... [3 marks] marks]

(d) Record the results of the experiment in the table. Beaker   A Observation

B [3 marks] marks]

(e) What conclusion can you make from your result? …………………………………………………………………………………………....

[3 marks] marks]

(f) Explain your your answer in part (e). …………………………………………………………………………………………....

Chemistry Perfect Score Module 2009

[3 marks] marks]

79

18. If the body of a bus is made of iron, it would easily rust due to its exposure to air  and water. Such a body is soft and can be easily dented in an accident. Thus, to overcome these problems, the body of the bus is made of steel Referring to the above situation, design a laboratory experiment to compare iron and steel based on one of the following properties: properties: Resistant to rust or hardness The experiment designed must include the followings: (i) Problem statement (ii) Hypothesis (iii) Lists of substances and apparatus (iv) Procedure (v) Tabulation of data [17 marks] 19.

Diagram 19 shows three reagent bottles containing three colourless organic liquids X, Y and Z.

X

Y

Z

Diagram 19 The three liquids are hexan-1-ol, hex-1-ene and hexane. The labels on the three bottles are missing. Plan a laboratory experiment to differentiate and identify the liquids in each of the three reagent bottles. Your description must include the following: (i) (ii) (iii) (iv) (vi)

Aim Variables List of materials and apparatus Procedure Tabulation of data [17 marks]

Chemistry Perfect Score Module 2009

80