Chapter 18, Problem 58QAP

Interpretation Introduction

Interpretation:

The corrosion resistant nature of aluminium should be explained.

Concept Introduction:

The oxidation and reduction can be identified by change in oxidation state. If oxidation state of atom of an element increases, it undergoes oxidation and if it decreases, it undergoes reduction.

The general oxidation and reduction half reactions are as follows:

$\text{A}\left(\text{s}\right)\to {\text{A}}^{+}\left(\text{a}\text{q}\right)+\text{e}$

Here, $\text{A}\left(\text{s}\right)$ undergoes oxidation to form ${\text{A}}^{+}\left(\text{a}\text{q}\right)$ with release of 1 electron. The oxidation state of A increases from 0 to 1.

Similarly,

${\text{B}}^{+}\left(\text{a}\text{q}\right)+\text{e}\to \text{B}\left(\text{s}\right)$

Here, ${\text{B}}^{+}\left(\text{a}\text{q}\right)$ undergoes reduction to form $\text{B}\left(\text{s}\right)$ with addition of 1 electron. The oxidation state of A decreases from 1 to 0.