Chemistry, Third edition

ACTIVITY SERIES OF METALS 113

Activity series of metals

The more negative the standard electrode potential, E°, of a redox couple

Mn(aq)/M(s), the more powerful a reducing agent is that metal. This means it is a

more reactive metal because it loses electrons more easily. We can arrange the metals

in order of reducing power, producing an activity seriesof metals (Table 7.2). The

metals at the top of the series are more reactive than those below.

A metal in solution can react with a metal ion that appears below it in the table.

Hydrogen is included so that the reactivity of metals with aqueous acids may be

worked out; when a metal above hydrogen is added to an acidic solution, a reaction

will occur and hydrogen gas is given off.

Never mix strongly reducing metals, such as potassium, with acid solutions – the

reactions are extremely violent.

7.6

Predicting reactions

Using the standard reduction potentials in Table 7.1, determine whether the following

reactions may occur:

(i) Br 2 (aq)I(aq)I 2 (aq)2Br(aq) (iii)Zn(s)2Fe^3 (aq)Zn^2 (aq)2Fe^2 (aq)

(ii)Cu(s)2H(aq)Cu^2 (aq)H 2 (g) (iv)2Fe^3 (aq)2I(aq)2Fe^2 (aq)I 2 (aq).

Exercise 7I

Example 7.4 (continued)

Br 2 (aq)2e2Br(aq) E°=1.09 V

Cl 2 (aq)2e2Cl(aq) E°=1.36 V

In this case, the direction of the arrows show that Br 2 (aq) and Cl(aq)stay as they

are. The conclusion is that there is no reaction at room temperature.

Table 7.2The activity series of metals

Reduction half-reaction E^ —(Mn(aq)/M(s))/V

K(aq)eK(s) 2.92
Ca^2 (aq)2eCa(s) 2.87
Na(aq)eNa(s) 2.71
Mg^2 (aq)2eMg(s) 2.37
Al^3 (aq)3eAl(s) 1.67
Zn^2 (aq)2eZn(s) 0.76
Fe^2 (aq)2eFe(s) 0.44
Ni^2 (aq)2eNi(s) 0.25
Sn^2 (aq)2eSn(s) 0.14
Pb^2 (aq)2ePb(s) 0.13
2H(aq)2eH 2 (g)  0
Cu^2 (aq)2eCu(s) 0.34
Ag(aq)eAg(s) 0.80
Au(aq)eAu(s) 1.68

Activity series of

metals

Write redox equations for

any reactions that might

occur when the following

substances are mixed:

(i) magnesium and silver

nitrate solution

(ii)copper and lead(II)

nitrate solution

(iii)nickel and copper(II)

sulfate solution

(iv)zinc and dilute hydro-

chloric acid (H(aq))

(v)copper and dilute

sulfuric acid (H(aq)).

Exercise 7J