The treatment of a marine artefact is shown - HSC - SSCE Chemistry - Question 33 - 2013 - Paper 1

The balanced chemical equation for the corrosion of tin can be represented as:

$\text{Sn} + 2\text{H}_2\text{O} + \text{O}_2 \rightarrow \text{Sn(OH)}_2$

This equation shows that tin reacts with water and oxygen to form tin hydroxide, which signifies its corrosion in shallow water.

Electron transfer plays a crucial role in corrosion reactions as it dictates the oxidation and reduction processes that occur. In a typical corrosion process, the metal oxidizes, losing electrons, while another species (often oxygen or water) reduces, gaining these electrons.

For instance, in the case of iron corrosion, the equation can be simplified as follows:

1. Oxidation: $\text{Fe} \rightarrow \text{Fe}^{2+} + 2e^-$
2. Reduction: $\text{O}_2 + 4e^- + 2\text{H}_2\text{O} \rightarrow 4\text{OH}^-$

Overall, the complete equation for the corrosion of iron can be summarized as:

$4\text{Fe} + 4\text{H}_2\text{O} + \text{O}_2 \rightarrow 4\text{Fe(OH)}_2$

This illustrates how electron transfer is fundamental to the corrosion process, highlighting the relationship between oxidation states and the subsequent formation of corrosion products such as hydroxides.