# Kirchhoff's equation

From AMS Glossary

## Kirchhoff's equation

A relation that equates the variation with temperature of the latent heat of a phase change to the difference between the specific heats of the two phases.

For the heat of vaporization this may be written as where

*L*_{v}is the latent heat of vaporization,*c*_{pv}is the specific heat at constant pressure of water vapor, and*c*_{w}is the specific heat of liquid water.