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Temasek Secondary School
Secondary 4 Pure Chemistry Test Practice 3

15

Topic: Reduction & Oxidation
Parent’s signature and comments:

…………………………………………………………………………………………………….
Name:
Class:

Register No:
Sec 4/

Date:

/

02 / 2016

Section A (3 marks)
Each question below is provided with four answers. Select the most appropriate answer and fill it in the brackets provided.
1. Iron metal is extracted from iron(III) oxide through a series of reactions in a blast furnace. The five reactions that occur in the blast furnace are:
Reaction 1: C + O2  CO2
Reaction 2: CaCO3  CaO + CO2
Reaction 3: CO2 + C  2CO
Reaction 4: Fe2O3 + 3CO  3CO2 + 2Fe
Reaction 5: CaO + SiO2  CaSiO3
Which of the above reactions are not redox reactions?
A

1 and 3 only

B

2 and 5 only

C

1, 2 and 5 only

D

3, 4 and 5 only

(

)

2. The nickel-cadmium rechargeable battery is based upon the following overall reaction. Cd + 2NiO(OH) + 4H2O  Cd(OH)2 + 2Ni(OH)2.H2O
What is the oxidation number of nickel at the beginning and at the end of the reaction? 1

beginning

end

A

+1.5

+2

B

+2

+3

C

+3

+2

D

+3

+4
(

)

3. When substance X is added to aqueous potassium iodide and acidified potassium manganate(VII) solution separately, both resultant solutions appear colourless.
In the two reactions, substance X is acting as
A

an oxidising agent only.

B

a reducing agent only.

C

both an oxidising agent and a reducing agent.

D

neither an oxidising agent nor a reducing agent.
(

)

Section B (12 marks)
Answer all the questions in the spaces provided below.
4.

An oxyacid is an acid that contains oxygen atom(s) bonded to hydrogen atom(s) and at least one other element. Sulfuric acid (H2SO4), phosphoric acid (H3PO4) and nitric acid (HNO3) are all oxyacids.
Chlorine forms several types of oxyacids. The table below shows some properties of oxyacids of chlorine. oxidation state of chlorine

reaction with magnesium
(all acids at equal volume and concentration)

name

formula

perchloric acid

HClO4

very vigorous

hypochlorus acid

HOCl

only a few bubbles seen

chloric acid

HClO3

+5

vigorous

chlorous acid

HClO2

+3

reacts readily

(a)

Complete the table by filling in the oxidation state of chlorine.

2

[2]

(b) (i)

Arrange the acids in ascending order of strength.
…………………………………………………………….…………………

(ii)

[1]

With reference to your answer in (b)(i) and the information from the table, deduce a trend that can be observed.
…………………………………………………………….………………….……
…………………………………………………………….…………………

(c)

[1]

Hypochlorus acid can be made by reacting chlorine with water.
The equation is shown below.
Cl2 + H2O  HCl + HOCl
Using oxidation numbers, show that this is a redox reaction.
…………………………………………………………….……………………………...
…………………………………………………………….……………………………...
…………………………………………………………….……………………………...
…………………………………………………………….……………………………...
…………………………………………………………….……………………………...
…………………………………………………………….………………………..

5.

[3]

In an experiment, air from a motorcar exhaust was passed through the apparatus as shown in the diagram.

3

(a)

Fill in the blanks in the table below. reagent change observed

anhydrous copper(II) sulfate acidified potassium dichromate(VI)

turned from white to blue turned from orange to green white precipitate formed limewater

name of substance causing the change

carbon dioxide gas
[2]

(b)

The presence of carbon monoxide is tested with palladium(II) chloride solution.
Palladium(II) chloride solution reacts with carbon monoxide and water vapour to form palladium metal. Two other acidic products are also formed.
(i)

Write the balanced chemical equation for the reaction.
……………………………………………………………………………..

(ii)

[1]

Identify the oxidising agent. Explain your answer.
……………………………………………………………………………………
……………………………………………………………………………………
……………………………………………………………………………..

END OF PAPER

4

[2]

Group
I

II

III

IV

V

VI

VII

0

1

4

H

He

Hydrogen

Helium

1

2

7

9

11

12

14

16

19

20

Li

Be

B

C

N

O

F

Ne

Lithium

Beryllium

Boron

4

3

5

Carbon

6

Nitrogen

7

Oxygen

8

Fluorine

9

Neon

10

23

24

27

28

31

32

35.5

40

Na

Mg

Al

Si

P

S

Cl

Ar

Sodium

Magnesium

Aluminium

12

11

13

39

40

45

K

Ca

Sc

Potassium

19

Calcium

20
85

48

Scandium

88

89

Sulfur

16

Chlorine

17

Argon

18

52

55

56

59

59

64

65

70

73

75

79

80

84

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

Vanadium

Chromium

Manganese

23

Titanium

22

Phosphorus

15

51

Ti

21

Silicon

14

24

25

91

93

Iron

26
101

96

Cobalt

Nickel

27
103

Copper

28
106

29
108

Zinc

30
112

Gallium

Germanium

31
115

32
119

Arsenic

33
122

Selenium

34
128

Bromine

35
127

Krypton

36
131

Rb

Sr

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

I

Xe

Rubidium

Strontium

Yttrium

Zirconium

Niobium

Molybdenum

Technetium

Ruthenium

Rhodium

Palladium

Silver

Cadmium

Indium

Tin

Antimony

Tellurium

Iodine

Xenon

37
133

38
137

39
139

40
178

41
181

42
184

43
186

44
190

45
192

46
195

47
197

48
201

49
204

50
207

51
209

52

53

54

Cs

Ba

La

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

Tl

Pb

Bi

Po

At

Rn

Caesium

Barium

Lanthanium

Hafnium

Tantalum

Tungsten

Rhenium

Osmium

Iridium

Platinum

Gold

Mercury

Thallium

Lead

Bismuth

Polonium

Astatine

Radon

55

56
226

57
227

72

Fr

Ra
Radium

74

75

76

77

78

79

80

81

82

83

84

85

86

Ac

Francium

73

Actinium

87

89

88

+
140

*58-71 Lanthanoid series
+90-103 Actinoid series

a
X

Key b a = relative atomic mass
X = atomic symbol b = proton (atomic) number

141

144

Ce

Pr

Nd

Cerium

58
232

Praseodymium

59

157

159

162

165

167

169

173

175

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

Neodymium

Promethium

Samarium

Europium

61

62

63

Pa

U

Thorium

Protactinium

Uranium

91

152

Sm

60
238

Th
90

150

Pm

92

Np
Neptunium

93

Gadolinium

64

Terbium

65

Dysprosium

66

Holmium

67

Erbium

68

Thulium

69

Ytterbium

70

Lutetium

71

Pu

Am

Cm

Bk

Cf

Es

Fm

Md

No

Lr

Plutonium

Americium

Curium

Berkelium

Californium

Einsteinium

Fermium

Mendelevium

Nobelium

Lawrencium

94

95

5

96

97

98

99

100

101

102

103

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