Applications
The Gibbs-Duhem equation is useful because it relates individual chemical potentials. For example, in a binary mixture, at constant temperature and pressure, the chemical potentials of the two participants are related by
Every instance of phase or chemical equilibrium is characterized by a constant. For instance, the melting of ice is characterized by a temperature, known as the melting point at which solid and liquid phases are in equilibrium with each other. Chemical potentials can be used to explain the slopes of lines on a phase diagram by using the Clapeyron equation, which in turn can be derived from the Gibbs-Duhem equation. They are used to explain colligative properties such as melting point depression by the application of pressure. Both Raoult's law and Henry's law can be derived in a simple manner using chemical potentils.
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