Question

Explain how the activity series accounts for each of the following: [4 MARKS]
(a) occurrence of metals
(b) tendency to corrosion
(c) reaction with water
(d) reaction with acid.

Answer 1

Each Part: 1 Mark

In the activity series, metals are arranged in the decreasing order of their reactivity. The most reactive metal is at the top while the least reactive metal is at the bottom of the series.
(a) Occurence of metals: Metals at the bottom of the series are least reactive. As such these metals occur in their native state. For example, gold, silver, platinum. Other metals mostly occur in combined state as oxides, sulphides, carbonates etc.

(b) Tendency to corrosion: Metals high up in the activity series, being most reactive, corrode easily. On the other hand, metals at the bottom of the activity series, being less reactive, generally do not undergo corrosion.

(c) Reaction with water: Metals like K, Na etc. which are high up in the activity series, being more reactive, react even with cold water to produce hydrogen.
Metals like Mg, Al, Fe etc. which are in the middle of the activity series react with hot water or steam to produce hydrogen. Metals like Cu, Ag, Au, Pt etc. which are at the bottom of the series, being least reactive do not react with water.

(d) Reaction with acids: Metals high up and in the middle of the series react with dilute acids $(HCl,H_{2}S{O}_4)$ to give hydrogen. Metals at the bottom of the series do not react with dilute acids.