# Question #635ea

Jun 29, 2016

It is an equation that relates equilibrium constant to temperature.

#### Explanation:

Equilibrium constants can change according to temperature. The Van't Hoff equation defines the change in equilibrium constant as a function of temperature. The equation under standard conditions is defined as:

$\frac{d \ln {K}_{e q}}{\mathrm{dT}} = \frac{\Delta H}{R {T}^{2}}$

Where $\Delta H$ is the standard enthalpy change of the reaction, T is the temperature in Kelvins, R is the gas constant (8.314 j/K/mol), and ${K}_{e q}$ is the equilibrium constant.

One of the main applications of the Van't Hoff equation is to make estimations of the equilibrium constant at a specified reaction temperature. To do this, enthalpy of reaction is assumed to be constant over the temperature range considered. It can be a useful exercise, for example in industrial applications where chemical engineers need to check what improvement in yield can be achieved by raising the reaction temperature of an equilibrium system.