Question

What reaction is represented by the equation `Au^(3+) + 3e^(-) -> Au`?

Answer 1

A reduction reaction.

Explanation:

The gold ion has been reduced in the sense that its charge has been reduced by accepting electrons.

`"Reduction"` reactions thus involve formal acceptance of electrons. `"Oxidation"` reactions involve formal loss of electrons. Given these formalisms, electron transfer between elements and compounds, always result in oxidation or reduction of the reactants.

The reverse reaction, which would require highly oxidizing acids to accomplish, is an oxidation reaction:

`AurarrAu^(3+) + 3e^-`