CAMBRIDGE INTERNATIONAL AS & A LEVEL CHEMISTRY: COURSEBOOK
Exam-style questions and sample answers have been written by the authors. In examinations, the way marks are awarded
may be different.
Coursebook answers
Chapter 7
Self-assessment questions
1
a
i
H2
ii
a
sodium sulfate(IV)
CO
b
sodium sulfate(VI)
iii
Mg
c
iron(II) nitrate(V) or iron(II) nitrate
b
i
I2O5
d
iron(III) nitrate(V) or iron(III) nitrate
ii
SO2
e
iron(II) sulfate(VI) or iron(II) sulfate
iii
CH2CH2
f
copper(I) oxide
2 a i
Cl2 + 2e− → 2Cl− reduction
2I− → I2 + 2e− oxidation
g
sulfuric(IV) acid
h
manganese(VII) oxide
ii
2Mg → 2Mg2+ + 4e− (or
Mg → Mg2+ + 2e−) oxidation
O2 + 4e− → 2O2− reduction
a
NaClO
b
Fe2O3
c
KNO2
d
PCl3
a
H2SO4 + 6HI → S + 3I2 + 4H2O
b
2HBr + H2SO4 → Br2 + SO2 + 2H2O
c
2V3+ + I2 + 2H2O → 2VO2+ + 2I− + 4H+
5
4 Fe → 4Fe3++ 12e− (or
Fe → Fe3+ + 3e−) oxidation
3O2 + 12e− → 6O2− (or
O2 + 4e− → 2O2−) reduction
6
iii
b
2IO 3− + 5Zn + 12H+ → I2 + 5Zn2+ + 6H2O
a
+5
b
+6
c
−2
d
+3
e
−3
f
+3
g
+4
a
i
0 to −1 = −1 (reduction)
ii
−3 to 0 = +3 (oxidation)
iii
+3 to +5 = +2 (oxidation)
3
4
b
i
iii
1
7
8
B
xidising agent is Br2; reducing
O
agent is I−
Reducing agent is As2O3; oxidising
agent is I2
Cambridge International AS & A Level Chemistry © Cambridge University Press 2020