Читать книгу Electroanalytical Chemistry - Gary A. Mabbott - Страница 15

The exchange of electrons between two chemical species is generally known as an oxidation/reduction process or redox reaction. In a redox reaction occurring in a homogeneous solution, one reactant gains electrons while the other reactant loses. It is often useful to consider a redox reaction from the perspective of one of the reactants. Consider a redox reaction between cerium and iron ions in aqueous solution:

(1.7)

The net reaction equation does not show any electrons as either reactants or products. However, it is useful to separate the two reactants into “half reactions” where electrons do appear.

(1.8)

(1.9)

A process in which a chemical species accepts one or more electrons is known as a reduction reaction; a process in which a species loses electrons is an oxidation reaction. Writing the half reactions indicates that the Fe²⁺ ion is being oxidized and the Ce⁴⁺ ion is being reduced. It also clearly states how many electrons are being transferred per mole of a given reactant.