The Gibbs free energy | Post-16 thermodynamics tutorials

The total entropy change of a system and its surroundings can be used to predict the direction of a reaction. However, chemists often prefer to think in terms of energy rather than entropy.

In chemical thermodynamics, the Gibbs free energy gives scientists an alternative function for predicting the direction or feasibility of a reaction, based on the more familiar concept of energy.

This tutorial introduces students to the Gibbs free energy and invites them to develop and apply their understanding through a range of important and related ideas. Key topics include:

• Equilibrium and equilibrium mixtures
• The relation between the Gibbs free energy, temperature and the equilibrium constant
• Constructing and interpreting Ellingham diagrams

The tutorial also features a video demonstration designed to illustrate one example of how free energy might be used.