Periodic Table SQ
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
Structured Questions Chemistry: Chapter 49 Periodic variation in physical properties of the elements Li to Ar Section 49.1 1 Complete the following table. Elements
Li
Be
B
C
N
O
F
Ne
Strong _______ Strong _______ bond between Nature of bond between _________ and Weak _______________ between _________ and ____________ molecules or atoms bonding ____________ of the bonded atoms Structure
____________
____________
____________ [5M]
2 Answer the following questions. (a) What does ‘periodicity’ mean? (b) Explain why metallic character generally decreases across a period. (c) Explain why metallic character generally increases down a group. [6M] Section 49.2 3 It is observed that the melting points of elements follow a periodic pattern in the Periodic Table. (a) Sketch the trend of melting points of elements across Period 3. (b) Explain the trend of melting points from Group I to III elements in Period 3. (c) Which element in Period 3 has the highest melting point? State its structure. [8M] 4 Answer the following questions. (a) Sketch the trend of melting points of elements across Period 3. (b) Sketch the trend of the relative electrical conductivities of elements across Period ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
3 at room temperature. (c) Sketch the trend of the relative electrical conductivities of elements across Period 2 at room temperature and compare it with the result in (b). [8M] 5 (a) Explain the trend of melting points of Period 3 elements. (b) Explain the trend of relative electrical conductivities of Period 3 elements at room temperature. [7M] 6 Answer the following questions. (a) Sketch the trend of melting points from sodium to argon. (b) Explain why the melting point of carbon is the highest in Period 2. [5M] 7 Carbon can exist in the form of graphite or diamond. (a) Which form of carbon can conduct electricity? Explain briefly. (b) Explain the difference in hardness between graphite and diamond. (c) Give the name of structure of carbon. [7M] 8 There is periodicity in melting point of elements in the Periodic Table. (a) Sketch the trend of melting points of elements across Period 2. (b) Sketch the trend of melting points of elements across Period 3. (c) Explain the difference in melting points between lithium and sodium. (d) Explain the difference in melting points between chlorine and fluorine. (e) Explain the difference in melting points between carbon and silicon. [13M] 9 There is periodicity in electrical conductivity of elements in the Periodic Table. (a) Sketch a graph to show the variation of relative electrical conductivities of elements across Period 3 at room temperature. (b) Explain the difference in electrical conductivities between magnesium and sodium. [5M]
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
Relative electrical conductivity
10 The graph below shows the variation in relative electrical conductivity of some elements.
Atomic number It is known that all the above elements are from Period 2 and Period 3. (a) Predict the value of x. (b) Which of the above elements is a noble gas? (c) Explain why the element with atomic number of x + 8 is not an electrical conductor at room temperature. (d) Explain why the element with atomic number of x + 7 has higher electrical conductivity than the one with atomic number of x + 6. [5M] 11 Concerning molecules of nitrogen, oxygen and fluorine. (a) State the period that they belong to. (b) State and explain whether there is a large difference in melting points of the three elements. (c) Phosphorus has the same structure as the above three elements. A student claimed that phosphorus should have a melting point close to them. Comment on his statement. [6M] 12 Across Period 3 of the Periodic Table, the elements change from metals to semi-metals and then non-metals. (a) Classify the elements across Period 3 according to their structures. (b) (i) Give the definition of ‘melting point’. ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
(ii) Sketch the trend of the melting points of elements across Period 3. (iii) Explain the trend of the melting points for Group I to Group IV elements in Period 3. [11M] 13 The information of four elements in the Periodic Table is listed below. Element
Electronic configuration
W
2, 1
X
2, 3
Y
2, 8, 6
Z
2, 8, 8
Physical state at 25C
Melting point (1-highest, 4-lowest)
Electrical conductivity
(W, X, Y and Z are not chemical symbols.) (a) Complete the above table. (b) (i) Give the names of the above elements. (ii) Classify the above elements as metals, semi-metals or non-metals. (c) Comment on the melting points of these elements. (d) Comment on the electrical conductivities of the above elements. (e) Draw diagrams to represent the structures of elements X and Y. [17M] 14 The table below shows some properties of elements in Period 2 of the Periodic Table: Elements Electrical conductivity Melting
Li
Be
C
F
Ne
conductor
conductor
depends on its structure
insulator
insulator
181
1278
3550 to 3675
219
249
point (C)
(a) Give the names of the groups consisting of Li, Be, F and Ne respectively. (b) (i) Explain why the electrical conductivity of carbon depends on its structures. (ii) Draw diagrams to represent the structures of two allotropes of carbon. (c) (i) Both Li and Be are metals. Explain their difference in melting point. (ii) Explain why F and Ne have relatively lower melting points. [14M] 15
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
The elements across Period 2 show periodic pattern. By referring to the type of bonding and structure, explain the following: (a) The melting point of beryllium is higher than that of lithium. (b) The melting point of carbon is higher than that of nitrogen. (c) The melting point of lithium is higher than that of fluorine. [9M] 16 Briefly explain the following: (a) Electrical conductivity increases from sodium to aluminium. (b) Graphite and diamond are allotropes of carbon. However, they have very different electrical conductivity. (c) Boron and aluminium belong to the same group but they have different electrical conductivities at room temperature. [8M] 17 A student claimed that ‘Electrical conductivity depends on the presence of delocalized electrons of metals. Graphite is able to conduct electricity so it is a metal.’ Comment on his statement. [5M]
Chemistry: Chapter 50 Bonding, stoichiometric composition and acid-base properties of oxides of the elements Na to Cl Section 50.1 18 Across a period, the electronegativities of elements increase. (a) Define ‘elecronegativity’. (b) Which oxide, Na 2 O or Al 2 O 3 , possesses more ionic character? Explain. (c) Except Na 2 O, sodium forms one more oxide with oxygen. Give the chemical formula of this oxide. State the oxidation number of oxygen in this oxide. (d) Burning sodium in air will produce two oxides of sodium. Write a balanced equation for the reaction. [6M] Section 50.2 19 Complete the following table for oxides of Period 3 elements: ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
Oxide
Na 2 O
Colour and state
MgO
Al 2 O 3
SiO 2
P 4 O 10
___________________
at 25C Structure Acid-base property
___________________ ____________
________
________
SO 2
Cl 2 O
______ ______
______ ______
___________________ _______________ [9M]
20 Answer the following questions. (a) Describe the trend of electronegativities of elements across Period 3. (b) Explain why the electronegativities of elements affect the bonding and structure of the oxides of elements across a period. (c) State the chemical properties of ‘basic oxides’ and ‘acidic oxides’ with ONE named example from Period 3 elements respectively. [8M] 21 X, Y and Z are Period 3 elements. The table below summarizes some information about them: X
Y
Z
Empirical formula of oxide
X2O
Y2O3
Z2O
Melting point
Very high
Very high
Low
Acid-base property of oxide
Basic
Amphoteric
Acidic
(a) Suggest what X, Y and Z are. (b) Explain the behaviour of the oxides in water with appropriate equations, if any. [8M] 22 Na, Mg, Al, Si, P and S are Period 3 elements which form oxides when they are burned in an excess amount of oxygen. (a) Give the formula of an oxide formed for each element. (b) Write a balanced equation for the reaction between P 4 O 10 and water. (c) Write a balanced equation for the formation of Al 2 O 3 from its elements. (d) Write a balanced equation for the reaction between SiO 2 and hydroxide ion. (e) Write a balanced equation for the reaction between Cl 2 O and water.
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
[7M] 23 The following table shows the melting point of the oxides formed from three Period 3 elements. Oxide
A
B
C
Melting point (C)
2752
72
1610
(a) (b) (c) (d)
Which of the oxides is most likely to have a simple molecular structure? Explain. Deduce the structure of A if it does not react with water and acids. State what A should be. Give the name of C if it burns with a yellow flame in air. State its structure. [6M]
24 (a) (i) Al 2 O 3 can react with acids or alkalis. What is the type of this oxide? (ii) Write balanced equations for the reactions of Al 2 O 3 with hydrochloric acid and potassium hydroxide respectively. (iii) The oxide of a Period 2 element is also amphoteric. Write balanced equations for the reactions of this oxide with sulphuric acid and sodium hydroxide respectively. (Hint: This oxide is a metal oxide.) (b) The structure of P 4 O 10 is shown below:
(i)
Based on the structure above, draw the structure of P 4 O 6 .
(ii) Write balanced equations for the reactions of water with P 4 O 6 and P 4 O 10 respectively. [8M] 25 A student used a burette to carry out a titration. His teacher told him that the burette was corroded by sodium hydroxide, so he should use a new one. (a) Explain, with a balanced equation, why the burette was corroded by sodium hydroxide. (b) Give the name of the sodium-containing product in (a). (c) Sometimes we cannot avoid using alkaline solution as the titrant. Suggest TWO ways to minimize the degree of corrosion. ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
(d) Explain why sodium hydroxide CANNOT be used as a primary standard. [8M] 26 Answer the following questions: (a) (i) Sulphur dioxide and sulphur trioxide are oxides of sulphur. Draw their structures. (ii) Write a balanced equation for the conversion of sulphur dioxide to sulphur trioxide. Give the name of the catalyst used. (iii) State the colour of SO 2 . (b) (i) Draw the structure of dichlorine oxide. (ii) State the colour of dichlorine oxide. [7M] 27 A student tried to find out the acid-base properties of different oxides. He selected Na 2 O, Al 2 O 3 and SiO 2 as the samples. Then he tried to dissolve the three oxides into water. (a) State the observations for each oxide. Write equations for any reactions occurred. (b) Classify the solutions or liquids obtained as acidic, neutral or alkaline. (c) To confirm the properties of Al 2 O 3 , it was reacted with dilute nitric acid and dilute sodium hydroxide respectively. Write equations for the reactions occurred. (d) Use ONE word to describe the behaviour of Al 2 O 3 . [10M] 28 Consider the oxides of three Period 3 elements, Mg, P and S. (a) Draw the structures of phosphorus pentoxide and sulphur dioxide. (b) Write equations for the reactions occurred when the three oxides are added to water respectively. (c) Which of the three oxides can be used to convert carboxylic acid (RCOOH) to acid anhydride ((RCO) 2 O)? (Hint: Two carboxylic acid molecules react to form one acid anhydride molecule.) [6M] 29 Silica glass is mainly composed of SiO 2 . (a) Draw the structure of SiO 2 . (b) Below are two precautions of using silica glass which were stated by two students: 1. It should not be used to store alkaline solutions. ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
2. It should not be used to store acidic solutions. State whether each of them is correct or not. Explain your answer briefly. [6M] 30 Phosphorus pentoxide (P 4 O 10 ) is a white solid. (a) State the observation if P 4 O 10 is mixed with water containing universal indicator. Explain your answer with an equation. (b) Suggest ONE use of P 4 O 10 . (c) A student claimed that P 4 O 10 contains two P 2 O 5 molecules. Comment on his statement with the illustration of the structure of P 4 O 10 . [7M] 31 Granite is very hard, durable and highly resistant to most chemicals. (a) (i) State the major composition of granite. (ii) State the nature of bonding of the compound in (i). (b) The major constituent of most commercial glass is silica. (i) Put some glass powder into a test tube. Add a small amount of sodium hydroxide solution. Put the tube in an ultrasonic bath for a few minutes. Then add 12 drops of methyl orange to the solution. What is the colour of the reaction mixture? (ii) Explain why there is a colour change in (i). (iii) What makes commercial glass have different colours? (c) (i) Silica glass bottles are not suitable for storing sodium hydroxide solution. Explain why. (ii) What kind of container is suitable for storing sodium hydroxide solution? [8M] 32 Some oxides of Period 3 elements were tested and the results were shown below. Oxide
Solubility in water
pH of solution Reaction with dilute acids
Reaction with dilute alkalis
A
Soluble
3
No
Yes
B
Slightly soluble
10
Yes
No
C
Insoluble
7
No
Yes
D
Insoluble
7
Yes
Yes
(A, B, C and D are not chemical symbols.) (a) Classify AD as oxides of metal, semi-metal or non-metal. (b) Classify AD as acidic, basic or amphoteric. ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
(c) Suggest what C and D are. Explain your answer. (d) Which of the above oxides is likely to have the lowest melting point? Explain your answer. [11M] 33 Consider the oxides of Period 3 elements. (a) Briefly describe the trend of nature of the oxides. (b) Which of the oxides is amphoteric? Illustrate its properties with suitable chemical equations. (c) Which of the oxide(s) consist(s) of V-shaped molecules? (d) Phosphorus pentoxide reacts vigorously with water to form phosphoric acid. (i) Write a chemical equation for the reaction. (ii) Explain why anhydrous phosphoric acid is viscous. Use a diagram to illustrate your answer. (Hint: H 3 PO 4 is in molecular form.) (iii) State and explain the basicity of phosphoric acid. [11M] 34 The table below shows the properties of some oxides of the elements in Period 3. Atomic numbers of X, Y and Z are arranged in ascending order. Element
X
Y
Z
Formula of oxide
XO
Y2O3
ZO 2
Melting point (C)
2800
2054
1610
Behaviour of oxide in water
alkaline solution
amphoteric
insoluble in water
(X, Y and Z are not chemical symbols.) (a) Identify X, Y and Z. (b) (i) Draw the electron diagram of XO. (ii) With the help of chemical equations, explain why an alkaline solution is formed when XO dissolves in water. (c) What is the meaning of ‘amphoteric’? Write TWO ionic equations to show the amphoteric properties of Y 2 O 3 . (d) Explain why ZO 2 does not dissolve in water. [10M] 35 Sodium oxide (Na 2 O), aluminium oxide (Al 2 O 3 ) and phosphorus pentoxide (P 4 O 10 ) are white solids at room temperature and pressure. The melting points of the oxides are 1275C, 2072C and 569C (sublimes at 360C) respectively. ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
(a) Outline the experimental procedure to identify the three compounds. Give related chemical equations and explanation. (b) Explain why the melting points of alumininium oxide and sodium oxide are much higher than that of phosphorus pentoxide. [7M] 36 The melting points of gallium oxide and arsenic oxide are 1795C and 315C respectively. Gallium oxide and arsenic oxide have the following compositions by mass. Gallium oxide: Ga (74.4%), O (25.6%) Arsenic oxide: As (65.2%), O (34.8%) (a) Calculate the empirical formula of gallium oxide and arsenic oxide. (b) Explain the difference in their melting points. [7M] 37 The table below shows the properties of some oxides of Period 3 elements. Oxide
SiO 2
P 4 O 10
SO 2
Melting point (C)
1650
569
72.4
Behaviour of oxide in water
Insoluble
Reacts with water to form acidic solution
Reacts with water to form acidic solution
(a) Explain the following phenomena with the help of equations. (i) P 4 O 10 and SO 2 react with water to give acidic solutions. (ii) SiO 2 does not dissolve in water but it is an acidic oxide. (b) Explain why SiO 2 and SO 2 have very different melting points. (c) Suggest a common use for each of the following oxides. (i) P 4 O 10 (ii) SO 2 [11M] 38 Aluminium oxide (Al 2 O 3 ) is an amphoteric oxide. (a) What is the meaning of ‘amphoteric’? (b) Apart from aluminium oxide, give ONE more example of amphoteric oxides. (c) It is known that aluminium hydroxide is also an amphoteric substance. (i) Write an equation for the reaction between aluminium hydroxide and sulphuric acid. (ii) Write an equation for the reaction between aluminium hydroxide and ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
sodium hydroxide. (d) Suggest a method to convert aluminium oxide to aluminium. [5M] Chemistry: Chapter 51 General properties of transition metals Sections 51.151.2 39 Transition metals occupy the central region of the Periodic Table in Periods 4, 5, 6, and 7. They are different from most main group metals in different properties. (a) Explain why transition metals across a period have similar chemical properties. (b) Explain why sodium can be cut by a knife whereas copper cannot. (c) Topaz is a kind of gemstones with yellow colour. Suggest the ions it contains. (d) State the colour of the pigment that contains zinc. [7M] Section 51.3 40 Transition metals usually have various oxidation states and show different colours in their compounds. (a) State the colour of V3+(aq) ions. (b) V3+(aq) ions can be reduced by Zn. (i) Write a balanced ionic equation for the reaction. (ii) State any observable change during the reaction. (c) A compound of vanadium can be used as a catalyst in an industrial and chemical process which manufactures sulphuric acid. (i) State the compound of vanadium used as the catalyst. (ii) State the oxidation state of vanadium in this catalyst. (iii) State the industrial and chemical process. [6M] 41 Iron has two common oxidation states. (a) State these two kinds of iron ions. (b) Which of the two iron ions is a reducing agent? (c) Suppose chlorine gas is bubbled into a solution containing the ions mentioned in (b). State the observation. (d) Write an equation for the reaction involved in (c). [4M] 42 ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
Chromium has a wide range of oxidation states in its compounds. (a) (i) List the TWO common oxidation states of chromium. Give ONE corresponding ion for each oxidation state. (ii) State the colour(s) of the ions in (a)(i). (b) Acidified potassium dichromate solution is extensively used in volumetric analysis for determining the amount of a reducing agent. (i) Write the ionic half equation for dichromate ions. (ii) What is the colour at the end point if a colourless reducing agent is used. (iii) Acidified potassium dichromate solution can be used to test the presence of both hydrogen sulphide and sulphur dioxide. Write the equations for the reactions involved. (iv) Explain why acidified potassium dichromate solution is not commonly used in the redox titration involving iodide ions. [10M] 43 Most of the transition metals, e.g. titanium, vanadium and chromium show variable oxidation states in their compounds. (a) Explain why most of transition elements show variable oxidation states in their compounds. (b) (i) State TWO other transition metals which show variable oxidation states in their compounds. (ii) Give TWO examples for each transition metal stated in (b)(i). (c) State TWO transition metals which do not show variable oxidation states in their compounds. [9M] 44 A conventional breathalyzer is used to test the alcohol content present in a driver’s breath. It contains a solution of acidified potassium dichromate solution. If the driver’s breath contains appropriate amount of alcohol, the contents in the breathalyzer change from orange to green. (a) Explain the observation. (b) Give the oxidation numbers of chromium in ions involved. [4M] Section 51.4 45 The following flow chart shows the inter-conversions of different oxidation states of vanadium:
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
(a) State the oxidation numbers of vanadium in VO 2 +(aq) and VO2+(aq) respectively. (b) State the colours of V2+(aq) ions and V3+(aq) ions. (c) V 2 O 5 is used as a catalyst in Contact Process. (i) Write a balanced chemical equation for the reaction it catalyses. (ii) State the oxidation number of vanadium in V 2 O 5 . (d) Contact Process involves two stages. Stage 1: V 2 O 5 (s) + SO 2 (g) 2VO 2 (s) + SO 3 (g) (i) Write a balanced equation for stage 2. (ii) Explain why V 2 O 5 is considered as a catalyst in the process. [8M] 46 (a) MnO 2 (s) is a strong oxidizing agent and it can be used as a catalyst in some chemical processes. Give an example of such processes. (b) MnO 2 (s) can react with HCl(aq) to produce Cl 2 (g). (i) Write a balanced equation for the reaction. (ii) What is the colour of the resultant solution? Explain briefly. (c) KMnO 4 (aq) is a powerful oxidizing agent. (i) State the colour of KMnO 4 solution. (ii) Write a balanced equation for the reaction between KMnO 4 (aq) and FeSO 4 (aq). [6M] 47 Write balanced chemical equations for the following processes. State the catalyst used in each case. (a) Haber Process (b) Contact Process (c) Catalytic conversion in car exhausts (d) Decomposition of hydrogen peroxide (e) Ziegler-Natta polymerization of ethane [10M] 48 Transition metals and their compounds show catalytic properties. (a) State the meaning of a catalyst. (b) It is proposed that there are two steps in Contact Process: Step I: SO 2 (g) + V 2 O 5 (s) SO 3 (g) + 2X(s)
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
Step II: 2X(s) +
1 O 2 (g) V 2 O 5 (s) 2
(i) State what X is. (ii) State the function of oxygen. (c) It is known that a catalyst does not change any physical properties of the reactants. Suggest how a catalyst can speed up a reaction in terms of energy factor. (Hint: A catalyst increases the proportion of reactant particles which possess enough energy to have effective collisions.) [8M] 49 The diagram below shows how a catalyst catalyses the reaction between iodide ions and peroxodisulphate ions. I2
e
S 2 O 8 2
A
e I
B
SO 4 2
(a) Suggest what A and B are. (b) State all the reducing agents present in the diagram. (c) Write two equations to show how the reaction is catalysed if A is used as the catalyst. [7M] 50 (a) Explain the following phenomena. (i) Tranisition metals have various oxidation states. (ii) The strength of the metallic bonds in transition metals is very strong. (b) In each of the following statements, suggest a transition metal that fits the situation. (i) One of its cations has a blue colour. (ii) It is used in the manufacture of a variety of steel. (iii) It is used as anti-corrosion coating for iron. (iv) It is used to make the catalyst that catalyses the polymerization of ethene. [8M] 51 (a) Iron rusts when it is in contact with moist air. ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
(i) Write a chemical equation for rusting. (ii) State the change in oxidation state of iron during rusting. (b) Iron can react with dilute hydrochloric acid. (i) State the observable change(s) when a piece of iron metal is dropped into a test tube containing dilute hydrochloric acid. (ii) Write a chemical equation for the reaction involved. (iii) State whether the reaction is a redox reaction or not. Explain your answer in terms of changes in oxidation numbers. (c) In Haber Process, iron is used as a catalyst. (i) State the meaning of catalyst. (ii) Write a chemical equation for the reaction occurred in Haber Process. (d) The reaction between peroxodisulphate ions and iodide ions can be catalysed by adding iron(III) ions. The process involves two stages as below: Stage I: 2Fe3+(aq) + 2I(aq) 2Fe2+(aq) + I 2 (aq) Stage II: 2Fe2+(aq) + S 2 O 8 2(aq) 2Fe3+(aq) + 2SO 4 2(aq) (i) State the function of iron(III) ions in the first stage of the reaction. (ii) Explain why iron(II) ions can also be used to catalyse this reaction. (iii) Write an overall equation for this reaction. [14M] 52 Manganese is a transition metal with variable oxidation states in its compounds. The most common oxidation states for manganese in its compounds are +2, +4 and +7. (a) State the compounds in which manganese has oxidation states of +2, +4 and +7 respectively. (b) A compound of manganese is used as a catalyst in a chemical process. (i) State the compound of manganese used as a catalyst. (ii) State the chemical process. [5M] 53 The most common oxidation states for iron in its compounds are +2 and +3. Iron(II) chloride is prepared by reacting iron with dilute hydrochloric acid while iron(III) chloride is prepared by heating iron with chlorine gas. (a) Write chemical equations for the formation of iron(II) chloride and iron(III) chloride. (b) Suggest a chemical test to distinguish between iron(II) chloride and iron(III) chloride solutions. (c) The reaction between peroxodisulphate ions S 2 O 8 2 and iodide ions I can be catalysed by adding iron(II) ions or iron(III) ions. State how iron(III) ions ©Aristo Educational Press Ltd. 2010
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HKDSE Chemistry A Modern View Part XII Patterns in the Chemical World
catalyse the reaction with the aid of appropriate ionic equations. [9M] Section 51.5 54 (a) Write a balanced equation for the reaction between peroxodisulphate ions and iodide ions. (b) Describe briefly how the above reaction can be catalysed by iron(II) ions with the aid of appropriate ionic equations. (c) Give ONE application of iron in maintaining health. [6M] 55 When zinc ribbons are added to copper(II) sulphate solution, a reaction occurs. (a) (i) State the type of the reaction. (ii) Write a balanced chemical equation for the reaction. (b) State THREE observable changes during the reaction. (c) Give ONE daily application of zinc and copper respectively. [7M] 56 Transition metals and their compounds have important applications in industry and biological systems. (a) Give the names of the two catalysts used in catalytic converters. (b) Carbon monoxide and nitrogen monoxide react to form nitrogen and carbon dioxide in catalytic converters. Write a chemical equation for this reaction. (c) State the importance of iron in human body. (d) Titanium is used to make the body of space shuttles. Suggest TWO properties of titanium that make it suitable for this application. [6M]
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