Clausius-Clapeyron equation

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July 16, 2026

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The Clausius-Clapeyron equation is a thermodynamic relation that describes how the pressure of a substance changes with temperature during a phase transition, such as liquid to gas. It is particularly useful for understanding the relationship between vapor pressure and temperature.12

The equation can be derived by considering the changes in internal energy and volume during a phase change. A simplified version, often used in practice, assumes the vapor behaves as an ideal gas and the liquid volume is negligible. This allows for the calculation of how boiling points change with pressure, which is crucial for understanding phenomena like water's boiling temperature at different altitudes.12

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thermodynamics
The Clausius-Clapeyron equation
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