Chapter 11
Reactivity of metals
Chapter exercise (p.11-32)
1. (a) hydroxide; hydrogen
(b) oxide; hydrogen
2. metal; reactivity series
3. electrons; positive/metal; electrons
4. displace
5. ionic; equation; spectator
6. lower
7.
(a) 4Al(s) + 3O2(g)  2Al2O3(s)
(b)
(c)
(d)
(e)
(f)
8.
2C2H6(g) + 7O2(g)  4CO2(g) + 6H2O(l)
2Cu(NO3)2(s)  2CuO(s) + 4NO2(g) + O2(g)
3CuO(s) + 2NH3(g)  3Cu(s) + N2(g) + 3H2O(l)
4FeS2(s) + 11O2(g)  2Fe2O3(s) + 8SO2(g)
2Al(s) + 3Fe2+(aq)  2Al3+(aq) + 3Fe(s)
(a) Magnesium dissolves and colourless gas bubbles evolve.
Mg(s) + H2SO4(aq)  MgSO4(aq) + H2(g)
(b) Calcium burns quite vigorously with a brick-red flame to produce a white
powder.
2Ca(s) + O2(g)  2CaO(s)
(c) Potassium melts to form a silvery ball. The ball moves about very quickly
on the water surface with a hissing sound. It burns with a lilac flame.
2K(s) + 2H2O(l)  2KOH(aq) + H2(g)
(d) Magnesium gives an intense white light. A white solid is produced.
Mg(s) + H2O(g)  MgO(s) + H2(g)
(e) Zinc dissolves and colourless gas bubbles evolve.
(f)
Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g)
Copper slowly dissolves and some shiny silvery deposits form on the
copper surface. The solution gradually turns blue.
Cu(s) + 2AgNO3(aq)  Cu(NO3)2(aq) + 2Ag(s)
9.
(a)
(b)
(c)
(d)
(e)
H+(aq) + OH(aq)  H2O(l)
Cl(aq) + Ag+(aq)  AgCl(s)
Mg(OH)2(s) + 2H+(aq)  Mg2+(aq) + 2H2O(l)
Pb2+(aq) + 2I(aq)  PbI2(s)
2H+(aq) + CaCO3(s)  Ca2+(aq) + CO2(g) + H2O(l)
10. B
Refer to p.4 of chapter 11 for details.
11. A
(B): Dilute hydrochloric acid reacts with metals that are higher than copper in the
metal reactivity series.
(C): The insoluble lead(II) sulphate formed prevents lead from further reaction
with the acid.
(D): Magnesium has no reaction with cold water.
12. A
For a balanced equation, the number of each type of atoms is the same on both
reactant and product sides.
13. D
14. D
Refer to p.20 of chapter 11 for details.
15. C
From the observations of the addition of nickel to solutions of compounds X, Y
and Z, the order of metal reactivity is: X, Y > Ni > Z.
From the observation of the addition of iron to solutions of compounds X, Y and
Z, the order of metal reactivity is: X > Fe > Y, Z.
16. B
17. C
Ionic equations include only those ions that are produced or changed during the
reaction.
18. D
The ores of Al, Ca and Mg are stable. It is difficult to extract the metals from
them.
19. (a) Magnesium oxide
(b) Magnesium burns with a very bright white light.
(c) 2Mg(s) + O2(g)  2MgO(s)
(d) When calcium burns with oxygen, a brick-red light instead of a very bright
white light is produced. Hence, calcium is not suitable to replace
magnesium in the flashbulb.
20. (a) Silver
(b) Copper(II) ion
(c) Cu(s) + 2Ag+(aq)  Cu2+(aq) + 2Ag(s)
(d) Copper is less reactive than zinc as it cannot displace zinc from aqueous
zinc nitrate solution. On the other hand, copper is more reactive than silver
as it can displace silver from aqueous silver nitrate solution. Hence, the
ascending order of reactivity is: silver, copper, zinc.
21. (a) Oxygen
(b) Silver
(c) Hydrogen
(d) Potassium or sodium
(e) (i) Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g)
(ii) Zn(s) + Cu2+(aq)  Zn2+(aq) + Cu(s)
(f) A, C, B
22. E and B react with water but A does not. Hence, E and B are more reactive than
A.
E reacts vigorously with water while B reacts slowly. Hence, E is more reactive
than B.
A reacts with dilute hydrochloric acid while C and D do not. Hence, A is more
reactive than C and D.
D displaces C from an aqueous solution of compound C. Hence, D is more
reactive than C.
Therefore, the increasing order of metal reactivity is: C, D, A, B, E.