# Redox Reactions

## Read in this section

### Latimer Diagrams

When an element has a range of oxidation states, there exist a number of reduction potentials for conversions between the various oxidation states. So, many redox couples may exist for a given element, and their identities may also depend on the pH of the solution, as different species exist in acidic and basic solutions.

### Frost Diagrams

A Frost Diagram is another way of displaying the reduction potentials for the various oxidation states of a given element, X. It shows nE against the oxidation number N: here, E is the reduction potential for the X(N)/X(0) couple, and n is the number of electrons transferred in the conversion of X(N) to X(0).

### Kinetic Effects on Redox Chemistry

The use of reduction potentials to predict the course of reactions is limited to thermodynamic considerations only: if the overall reduction potential for the reaction, which is the difference of the reduction potentials of the individual couples, is positive, then there is a negative Gibbs free reaction energy and the reaction is thermodynamically spontaneous.

### The Nernst Equation

The use of standard reduction potentials to predict the course of a reaction is somewhat limited, in that they are only valid under standard conditions. However, they can be used to predict the course of redox reactions under nonstandard conditions.

### Standard Electrodes

Having defined the half-reaction and a potential associated with the reduction depicted by the half-reaction, we need to determine what the potential is.

### Half Reactions and Reduction Potentials

When a redox operation proceeds, one species is oxidised and the other is reduced. It is useful to think of these two processes separately.