# What factors affect the vapor pressure of a liquid?

Jan 4, 2016

$\ln \left({P}_{v a p}\right) = - \frac{\Delta {H}_{v a p}}{R} \left(\frac{1}{T}\right) + C$

#### Explanation:

The expression of vapour pressure is given by:

$\ln \left({P}_{v a p}\right) = - \frac{\Delta {H}_{v a p}}{R} \left(\frac{1}{T}\right) + C$

where, $\Delta {H}_{v a p}$ is the enthalpy of vaporization and it is a constant for a specific liquid.

$R$ is the universal gas constant: $R = 8.3145 \frac{J}{m o l . K}$.

$T$ is the temperature and $C$ is a constant.

Therefore, looking at the aforementioned expression, the only variable that affects the vapour pressure is temperature .