Cambridge International AS Level Chemistry
Answers to self-assessment questions
Answers to SAQs
Chapter 1
1
2
a
b
c
d
9
111.1
159.6
132.1
256.3
3 a i 0.33 mol
ii 0.25 mol
iii 0.25 mol
b mol Cl = 7.10
35.5 = 0.200 mol
0.20 × 6.02 × 1023
= 1.20 × 1023 (to 3 significant figures)
a 8.8 g
b 5.3 g
c 449.0 g
5
a 46.0 g Na → 78.0 g Na2O2
so 4.6 g Na → 7.8 g Na2O2
b 150.7 g SnO2 → 24 g C
so 14.0 g SnO2 → 2.23 g C
7100 × 24
46 = 52.2% (to 3 significant figures)
NH2
C4H9
CH
NH3
10
1.0
= 7.5
= 10
10 A C6H10
B C2Cl6
C C8H16
11 a i Mg(NO3)2
ii CaSO4
iii NaI
iv HBr
v Na2S
b i sodium phosphate
ii ammonium sulfate
iii aluminium chloride
iv calcium nitrate
13 a CaCO3(s) + 2HCl(aq)
→ CaCl2(aq) + CO2(g) + H2O(l)
b ZnSO4(aq) + 2NaOH(aq)
→ Zn(OH)2(s) + Na2SO4(aq)
so ratio of Si : Cl2 : SiCl4 = 1 : 2 : 1
Si + 2Cl2 → SiCl4
a
b
c
d
90
12.0
12 a Fe + 2HCl → FeCl2 + H2
b 2Al(OH)3 → Al2O3 + 3H2O
c 2C6H14 + 19O2 → 12CO2 + 14H2O
656.2
28.1 = 2 mol Si
284.0 = 4 mol Cl
2
71.0
340.2 = 2 mol SiCl
4
170.1
8
Hydrogen
simplest ratio is 3C to 4H
empirical formula is C3H4
76
a 32
Ge
b (20.6 × 70) + (27.4 × 72) + (7.7 × 73) + (36.7 × 74) + (7.6 × 75)
100
= 72.7
4
Carbon
14 a 2H+(aq) + 2OH–(aq) → 2H2O(l)
b Br2(aq) + 2I–(aq) → 2Br–(aq) + I2(aq)
15 a Cu2+(aq) + 2OH–(aq) → Cu(OH)2(s)
b Pb2+(aq) + 2I–(aq) → PbI2(s)
2 × 1000 = 1.0 mol dm–3
16 a i 40
50
–3
12
ii 60.0× 1000
250 = 0.80 mol dm
40 = 8 × 10–3 mol
b i 0.2 × 1000
50 = 5 × 10–4 mol
ii 0.01 × 1000
Cambridge International AS and A Level Chemistry © Cambridge University Press 2014
Cambridge International AS Level Chemistry
Answers to self-assessment questions
17 a number of moles of HCl = 0.100 × 15.00
1000
= 1.5 × 10–3 mol
–3
number of moles of Sr(OH)2 = 1.5 ×210
= 7.50 × 10–4 mol
concentration of Sr(OH)2 = 7.50 × 10–4 × 1000
25
= 3.00 × 10–2 mol dm–3
50
b number of moles of NaOH = 0.400 × 1000
–3
= 8.00 × 10 mol
–3
number of moles of H2SO4 = 8.00 2× 10
= 4.00 × 10–3 mol
1000
concentration of H2SO4 = 4.00 × 10–3 × 25.25
–1
–3
= 1.58 × 10 mol dm (to 3 significant figures)
20 = 1.20 × 10–3 mol
18 a 0.0600 × 1000
–3
b 0.100 × 24.00
1000 = 2.40 × 10 mol
c 1 mol metal hydroxide : 2 mol hydrochloric acid
d M(OH)2 + 2HCl → 2MCl + 2H2O
19 a 26.4
44.0 = 0.60 mol
0.60 × 24 = 14.4 dm3
b number of moles of He = 24120
000
= 5.0 × 10–3 mol
mass = 4.0 × 5.0 × 10–3
= 2.0 × 10–2 g
20 a 3 moles
b PH3 (ratio of volumes = ratio of moles)
c PH3(g) + 3Cl2(g) → PCl3(g) + 3HCl(g)
Cambridge International AS and A Level Chemistry © Cambridge University Press 2014