CHAPTER 11 : OXIDATION AND REACTION

1. Which of the following reactions occurs when molten lead(II) bromide is electrolysed by using carbon electrodes?

A Redox reactionB Metal corrosion of reactionC Reduction of bromide ion at cathodeD Oxidation of bromide ion at anode

2. Which of the following statements about reduction and oxidation is true?

A Reduction is a process of adding oxygenB Oxidation is a process of losing electronC Reduction is a process where the oxidation number of a substance

increases.D Oxidation is the process of adding hydrogen

3. Which of the following is reducing agent?

A ZincB Bromine waterC Acidified sodium dichromate(VI)D Acidified potassium manganate(VII) acidified

4. Which of the following reactions can’t be carried out byusing electrolysis method?

A Danielle CellB Extraction of AluminumC Decomposition of molten Lead(II)oxideD Recharging of Lead Acid Accumulator

5. The diagram shows the set up of the apparatus used to determine the position of hydrogen in reactivity series of metal.

Which of the following metal oxide will be reduced by hydrogen?

I Zinc oxideII Iron(III) oxideIII Copper(II) oxide

1

Metal oxide

Dry hidrogen gas

Burning of excess hydrogen gas

Heat

IV Lead[II) oxide

A I and II onlyB II and III onlyC II and IV onlyD II, III and IV only

6. Which of the following metal is easily oxidized?

A ZincB LeadC AluminiumD Magnesium

7. Which of the following reactions do not involve redox reaction?

I DisplacementII PrecipitationIII CombustionIV Neutralisation

A I and II onlyB I and III onlyC II and III onlyD II and IV only

8. Which of the following is not a redox reaction?

A Rusting of ironB Neutralisation reactionC Reaction in nickel cadmium cellD Extraction of iro from their ore

9. Which of the following does not occur during extraction of silver using carbon?

A Carbon is oxidized to carbon dioxideB Tin(IV) oxide, SnO2 is reduced to tinC Tin(IV) oxide, SnO2 act as a reducing agentD The oxidation number of carbon increases from 0 to +4

10. The following are the advantages of using carbon in extraction of metals except

A carbon is easily availableB the cost for using carbon is cheaperC carbon is located under tin in the reactivity series of metalD the by product of the reaction which is carbon dioxide is easy to eliminate

2

Carbon is used as a reducing agent in the extraction of metals, like iron and tin from their ores.

11. Electrolysis is a process when a chemical substance is decomposed by using electricity. Which of the following statement is true in an electrolysis process?

A Anion receives electron at anodeB Cation receives electron at anodeC Cation receives electron at cathodeD Anion releases electron at cathode

12. The diagram shows the set-up of the apparatus to determine the location of carbon in the reactivity series of metals.

What is the observation at the end of experiment?

A The mixture remains unchangedB A brown solid is producedC Carbon reacts as an oxidising agentD Copper(II) oxide is oxidized to copper

13. What is the purpose of carbon in the displacement process of iron?

A To reduce iron oxide B To decrease the melting point of iron C To change iron ore to molten iron D To oxidized the impurity in iron ore

14. Metal X is located between iron and zinc in the metal reactivity series. Which of the following metals can reduce X oxide?

A Copper

B Tin C Lead D Aluminium

3

Mixture of carbon powder and copper(II) oxide powder

Pipe-clay triangle

Tripod stand

Asbestos paper

Heat

15. Nickel is located between iron and zinc in the metal reactivity series. Which of the following metal can reduce nickel oxide?

I Tin II Lead III Aluminium IV Magnesium

A I and II only B II and III only C III and IV only D I,II,III and IV

16. All of the following metals can react as a reducing agent. Which one is the strongest?

A Iron B Sodium C Silver D Aluminium

17. Aluminium is extracted from its ore by electrolysis process. Why is aluminium cannot be extracted from its ore by heating it with carbon?

A Impure aluminium is producedB The cost of extraction is very highC Aluminium is more reactive than carbonD Aluminium can react with carbon

18. Which of the following shows the arrangement of the metal reactivity series with oxygen in ascending order?

A K,Na,Mg,Al B Sn,Fe,Zn,Cl C Zn,Fe,Sn,Pb

D Cu,Hg,Ag,Au

19. What is the name of compound which its formula is NaClO4?

A Sodium chlorate(III)B Sodium(I) chlorate(I)C Sodium chlorate(VII)D Sodium(I) chlorate(VII)

20. Which of the following substances can oxidize iron(II), Fe2+ ion to Iron(II), Fe3+ ion ?

A Zinc metalB Dilute sulphuric acid, H2SO4

C Hidrogen sulphide gasD Acidicfied potassium manganate(VII) solution

4

21. The following is an ionic equation,

Which of the following is true about that equation?

A Y2+ is oxidised to YB X2+ is a reducing agentC X is an oxidising agentD X donates electron to Y2+

22. The diagram below shows the set up of the apparatus to change iron(III), Fe3+ ion to iron(II), Fe2+ ion.

Which of the following can replace zinc powder in this reaction?

A Bromine waterB Tin(II) chloride solutionC Potassium hexacianoferate(II) solutionD Acidicfied potassium manganate(VII)

23. The diagram shows the set-up of the apparatus of an experiment. The apparatus is left for an hour.

Which of the following statements is not true?

A Electron transferred from electrode P to electrode QB Potassium iodide solution turn to brown in colourC The orange colour of acidified potassium dichromate(VII) decolourisedD The oxidation number of chromium change from +6 to +3

5

Electrode QElectrode P

Acidic dichromate(VII) solutionPotassium iodide solution

Dilute sulphuric acid

X[s] + Y2+[aq] X2+

[aq] + Y[s]

Iron(III) ion solution

Zinc powder

Heat

24. The equation shows the changes of iodide ion to iodine.Which of the following cannot make that ion change?

A Chlorine water.B Potassium bromide solution.C Acidified potassium manganate(VII) solution.D Acidified potassium dichromate(VI) solution.

25. The table shows some chemical changes occur in four chemical reactions.

Reactions Chemical changesWXYZ

Zinc atom changes to zinc ionMnO4ˉ changes to Mn2+

Iodide ion changes to iodineChlorine molecule changes to chloride ion

Among the chemical changes above, which one loses electron?

A W and XB W and YC X and YD Y and Z

26. The diagram shows the set up of the apparatus of an experiment to investigate the effect of corrosion to iron

Which of the following decrease the rate of rusting of iron?

A Ion Fe 2+ accept electron to form Fe B Metal X is less electropositive than iron C Metal X is more electropositive than iron D Sodium chloride solution is a strong electrolyte

6

Iron nail

Metal X

Sodium chloride solution

27. The diagram shows the reaction between hot lead powder with bromine gas.

Which of the following is correct ?

A White solid is producedB Lead atom oxidized to lead(II) ionC Oxidation number of Bromine decreases from 0 to -2D Bromine reacts as oxidising agent

28. When the mixture of lead(II) oxide and aluminium powder is heated, lead is produced as shown in the equation below.

This reaction occur because,

A lead is an amphoteric oxide B aluminium burns reactively C lead is a strong reducing agent

D aluminium is more reactive than lead

30. The following chemical equation shows a halogen replacement reaction.

Which of the following statement is true about the reaction?

A Bromine gas is a reducing agentB Bromide ion undergoes reduction C Iodide ion undergoes oxidationD Oxidation number of iodine changes from +1 to +2

7

Br2[g] + 2KI[aq] → I2[g] + 2KBr[aq]

3PbO + 2Al Al2O3 + 3Pb

Hot lead powder

Bromine gas

Gas jar spoon

31. In an experiment, concentrated sodium chloride solution is electrolised using carbon electrodes. Which of the following statement is true?

A Hidrogen,H+ ion is oxidizedB Chloride,Cl- ion acts as oxidizing agentC Sodium,Na+ ion undergoes oxidationD The oxidation number of hydrogen decreases from +1 to 0

32. The diagram shows a simple voltaic cell.

Which of the following, is reduced in that cell?

A CopperB Sodium ionC MagnesiumD Hidrogen ion

33. The diagram shows, a few drops of acidic potassium manganate(VII) solution are dropped into X solution.

If the purple colour of acidified potassium manganate(VII) is decolourised, X solution should be

A bromine water.B iron(II) ion solution.C iron(III) ion solution.D dichromate(VI) ionsolution.

8

Acidified potassium manganate(VII) solution

X solution

V

CopperMagnesium

Sodium sulphatesolution

34. The diagram shows chemical cell.

Which of the following, will happen in the cell?

A Magnesium rode becomes thinner.B The number of copper(II) ion increase.C Copper rode acts as a negative terminal.D Magnesium acts as an oxidation agent.

35. The equation below represents the displacement reaction between metal X, Y and Z.

Choose the correct statement for this reaction?

A Y is more electropositive than X B X and Z are oxidising agents C The arrangement of reactivity in descending order is Z ,X, Y D X2+ and Y2+ are reducing agents, where as Z2+ is an oxidising agent

36. The extraction of tin from its ore is a redox reaction. Which of the following Substances can be use to reduce tin(IV)oxide to tin?

A Carbon B Copper C Lead D Silver

37. Which of the following equations represents a redox reaction?

A HCl + KOH → KCl + H2O

B H2SO4 + Mg → MgSO4 + H2

C Pb(NO3)2 + K2CO3 → PbCO3 + 2KNO3

9

Copper(II) sulphate solution, 1.0 mol dm-3

Magnesium sulphate solution, 1.0 mol dm-3

Copper metalMagnesium metal

Reaction I : X (s) + Y2+ (aq) → X2+ (aq) + Y (s)Reaction II : Z(s) + X2+ (aq) → Z2+ (aq) + X(s)

D CaCO3 + 2HCl → CaCl2 + CO2 + H2

38. The rusting of iron can be reduced by coiling the iron with other metals.Which of the following metals can protect the iron from rusting?

A Zinc B Tin C Copper D Lead

39. Which of the following metals will increase in mass if heated in steam?

A CopperB MagnesiumC LeadD Silver

40. Reaction between acidified potassium dichromate,K2Cr2O7 with iron(II) sulphate,FeSO4 solution is a redox reaction. In this reaction, the oxidation number of chromium changes from

A +7 to +3B +6 to +3C +6 to +2D +5 to +1

41. Which of the following shows the correct oxidation number of manganese?

MnO MnO2 Mn2O3

A 2 4 6B 1 2 6C 1 2 3D 2 4 3

42.

Based on the above statement, which of the following metal can be used to protect tin from corrosion?

A ZincB CopperC LeadD Silver

43. The equation below, shows half equation for a redox reaction.

10

Corrosion of metal can be protected by using other metal

X2O72- + 14H+ + ne- → 2X3+ + 7H2O

From the equation, a X2O72- ion is reduced to two X3+ ion by receiving n

electrons, (ne-) as shown in the above half equation. What is the value of n?

A 2B 6C 8D 9

44. The equation shows a redox reaction.

In the reaction, what is the change in the oxidation number for nitrogen?

A -3 to 0B +3 to 0C +1 to -2D -2 to +2

45. When a piece of iron plated with X metal was scratched, the iron did not rust but when a piece of X metal plated with iron was scratched, the iron rusting very quickly. From the above observations, the arrangement of metals X, Y and iron in descending order in electrochemical series is

A Iron, X, YB X, iron, YC X, Y, ironD Y, iron X

46. The following equation shows a reaction between hydrogen and excess air.

In the reaction, the oxidation number of hydrogen changes from

A 0 to +1B 0 to +2C +2 to 0D +1 to +2

47. The chemical equation shows a redox reaction.

Which of the following is the changes of the oxidation number of nitrogen?

11

3CuO + 2NH3 → 3Cu + N2 + 3H2O

2H2 + O2 → 2H2O

2KNO3 → 2KNO2 + O2

∆

A +5 to +3B +6 to +4C +3 to +5D +4 to +6

48. Which of the following substances contains nitrogen with the highest oxidation number?

A N2O B KNO2

C HNO3

D NH4Cl

49. The equation below shows the reduction of iron(III) to iron(II) by Sn2+.What is the value of n in Snn+?

A 3B 4C 5D 6

50. Which of the following pair of substances, have the same oxidation number for the underlined elements?

A CrO42- and Cr2O7 2-

B KNO2 and NaNO3

C SO4 2- and SO32-

D KMnO4 and Mn2O3

STRUCTURED QUESTIONS

SECTION A

Answer all the questions

1. The diagram shows the set up of the apparatus to investigate transfer of

electrons at a distance between iron(II) sulphate solution and

12

2Fe 3+(aq) + Sn2+ (aq) 2 Fe2+(aq) + Sn n+(aq)

acidified potassium dichromate(VI) solution

The voltmeter shows reading. After a few minutes, solution at X side and Y side

of the u tube shows changes.

a) What is the function of dilute sulphuric acid?

__________________________________________________________

[1 M]

b) State the changes of colour in

(i) Iron(II) sulphate solution

__________________________________________________________

(ii) Acidicfied potassium dichromate(VI) solution

__________________________________________________________

[2 M]

c) Potassium dichromate(VI) solution contains potassium,K+ ion and

dichromate(VI),Cr2O72- ion. What is the oxidation number of chromium in

dichromate(VI), Cr2O72- ion?

13

Acidicfied potassium dichromate(VI) solution

V

X YIron(II) sulphate solution

Dilute sulphuric acid

_________________________________________________________

[1 M]

2. The diagram below shows the set-up of the apparatus used to investigate a

redox reaction.

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Potassium bromide solution

Chlorine water

Potassium iodide solution

Chlorine water

P Q

Test tube P is filled with 2 cm3 of potassium bromide while test tube Q is filled

with 2 cm3 of potassium iodide solution. A few drops of chlorine water is dropped

into both of the test tubes and shaked.

a) State one observation for the experiment.

__________________________________________________________

[1 M]

b) A little of product in test tube Q was mixed with tetra chloromethane

liquid. The mixture was shaken

(i) What is the colour of tetra chloromethane layer after the mixture was

shaken?

__________________________________________________________

[1 M]

(ii) Write an ionic equation to represent the reaction.

__________________________________________________________

[1 M]

c) Write the changes in the oxidation number of chlorine in both test tubes.

__________________________________________________________

[1 M]

15

d) Name one substance that can replace chlorine water in this experiment

and state the observation.

__________________________________________________________

__________________________________________________________

[2 M]

e) Transfer of electron at a distance is also a redox reaction. You are given

potassium bromide solution, chlorine water, potassium nitrate solution

and related apparatus. Draw the set-up of the apparatus diagram for the

experiment.

[2 M]

3. The diagram shows an experiment to investigate redox reaction for three

elements, X , Y and Zinc. X is in powder form located between calcium and

aluminium where Y is black powder and a non metal.

16 Heat

Potassium manganate(VII)

Glass wool

Y X zinc

This results are recorded as shown below.

Elements

Observation

During Heating After Heating

X Shining flame ……………………….........

Y Bright flame No residue

Zinc Very Bright glow …………………………….

a) What is the function of potassium manganate((VII) in the experiment?

_____________________________________________________________

[1 M]

b) Which one need to be heated first to get a perfect product, metal powder or

potassium manganate(VII) ?

_____________________________________________________________

[1 M]

c) State the elements that represent by X and Y ?

(i) X :________________________________________________________

(ii) Y: ________________________________________________________

[2 M]

d) State observation for X and Zinc after being heated and when cooled.

(i) X : _________________________________________

(ii) Zinc : _________________________________________

[2 M]

e) Residue from decomposition of zinc through heating process is mixed

with X and heated. A redox reaction occurs.

17

(i) Write chemical equation for the reaction.

____________________________________________________

(ii) State the changes of oxidation number for zinc in this reaction

____________________________________________________

[2 M]

(iii) From the above equation, determine the oxidising agent and

reducing agent

Oxidising agent

:___________________________________

Reducing agent

:___________________________________

[2 M]

4. The diagram shows the set up of the apparatus used to electrolised concentrated

sodium chloride solution with carbon electrodes.

18

a) Write all the ions present in the concentrated sodium chloride solution.

__________________________________________________________

[1 M]

b)

(i) State the observation at electrode P.

__________________________________________________________

[1 M]

(ii) Name the substance in (b)(i).

__________________________________________________________

[1 M]

c)

(i) Name the reducing agent in this reaction.

__________________________________________________________

[1 M]

(ii) Write the changes in oxidation number of reducing agent in (c)(i).

__________________________________________________________

[1 M]

d) The gas released at electrode Q is reacted with oxygen.

(i) Write the equation involved.

__________________________________________________________

[1 M]

19

A

Concentrated sodium chloride solution

Carbon electrode QCarbon electrode P

(ii) From the equation, determine whether this reaction is a redox reaction or

not base on the electron transfer.

__________________________________________________________

[1 M]

e) The gas released at electrode is passed through the test tube containing

potassium iodide.

(i) Write the ionic equation for the reaction in the test tube.

__________________________________________________________

[1 M]

(ii) From the equation, determine the oxidising agent and reducing agent for

the reaction.

__________________________________________________________

__________________________________________________________

[2 M]

SECTION B : ESSAY

Answer all questions. You are required to answer this section within 30 minutes.

1.

a) The table shows the set up of the apparatus and the results of an

experiment to investigate the effect of other metals to the rusting of iron.

20

Experiment

Observation after a

few days

Iron nail rusted Iron nail is not rusted

Explain the above results.

[4 M]

b)

Explain the above statement and draw the

set up of the apparatus used

for the electroplating process

[6 M]

c) A student conducted two experiments to investigate a redox reaction

between iron(II), Fe2+ ion with bromine solution and magnesium ribbon.

The table shows the set up of the apparatus for Experiment I and

Experiment II.

21

Electroplating of iron spoon with copper through electrolysis is a redox reaction

Iron nail

Copper metal

Water

Iron nail

Magnesium ribbon

Water

Experiment I II

Set up of the

apparatus

(i) Compare observations between Experiment I and Experiments II.

(ii) “Oxidising agent in a reaction can also act as a reducing agent in

another reaction”

Based on Experiment I and Experiment II, discuss this statement.

In your discussion, you need to write ionic equations.

[10 M]

SECTION C : ESSAY (Open Respond Item)

Order: Answer the following questions

The suggested time to answer the question in this section is 30 minutes.

a)

22

Metals which are located near the sea will be easily corrode.

Iron(II) sulphatesolution

Magnesium ribbon

Iron(II) sulphatesolution

Bromine water

Explain the above statement. [4 M]

b) (i) 3H2S(g) + 2HNO3(aq) → 3S(s) + 2NO(g) + 4H2O(l)

(iii) Pb(NO3)2(aq) + K2CO3(aq) → PbCO3(s) + 2KNO3(s)

The equation in (b)(i) represent the redox rection and the equation (b)(ii) is not a

redox reaction. Explain. [6 M]

c)

Describe an experiment to prove the above statement by using iron(II) sulphate

solution as the reducing agent with a named oxidising agent.

[10 M]

PAPER 3

Answer all question

23

Electricity can be produced from transferring of the electron in a distance

VCarbon electrodes

Solution P

Sulphuric acid, 1 mol dm-3

Potassium iodide solution, 1 mol dm-3

1. The diagram above shows the set up of the apparatus of an experiment by using

four different solutions. The voltmeter readings for all experiments are shown in

the table below.

a) State all the variables in the experiment.

Responding variable : ______________________________________________

Manipulated variable : ______________________________________________

Fixed variable : ______________________________________________

[ KK0510]

b) State the hypothesis for the experiment.

________________________________________________________________

________________________________________________________________

[KK0511]

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Experiment IIExperiment I

Experiment IVExperiment III

The diagram shows voltmeter reading for experiment I, II, III and IV.

Complete the table below.

Experiment Solution P Voltmeter reading/ V

I Potassium dichromate(VI) solution

II Chlorine water

III Bromine water

IV Potassium manganate(VII) solution

[KK0503]

c) State two observations from the above experiment not including

deflection of voltmeter needle.

__________________________________________________________

__________________________________________________________

[KK0501]

d) Predict the voltmeter reading if potassium iodide solution in

experiment(IV) is replaced with potassium bromide solution.

__________________________________________________________

[KK0505]

e) Arrange solutions P according to descending order as oxidising agent.

__________________________________________________________

[KK0502]

25

2. An experiment was conducted to determine the location of three elements, X, Y

and Z in the reactivity series of metal. X, Y and z are metals powder. After being

heated for a while. The following observations occur;

Element Observations

During Heating After Heating

26

X Brightly burned White powder

Y Faintly glowed Black powder

Z Fairly bright burned The powder is yellow when

hot and white when cold

a) Base on the experiment results of the experiment, state the inference that

we can make.

__________________________________________________________

[KK0504]

b) Draw the diagram for the set-up of apparatus for the above experiment.

[KK0506]

c) Name the elements represented by X, Y and Z.

(i) X : _________________

(ii) Y : _________________

(iii) Z : _________________ [KK0508]

d) How can you build a reactivity series of metal based on the reactivity of

metals with oxygen?

__________________________________________________________

__________________________________________________________

[KK0509]

e) In metal extraction, carbon is used to extract iron metal. Can we use

element Y to extract iron metal ?

__________________________________________________________

[KK0507]

27

3.

28

If iron is exposed to water and air, it will undergo rusting process quickly. So, in arab countries, iron pipe that carries oil is tied with magnesium bag to control it from undergoing rusting process.

Refer to the above situation, plan a laboratory experiment to show that

magnesium can control rusting process on iron.

Your experiment planning should consist the following matter.

(i) Aim of experiment/ Problem statement

(ii) All the variables

(iii) Hypothesis

(iv) List of apparatus and materials

(v) Procedure

(vi) Tabulation of data

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