# How do you calculate the vapor pressure of a solution?

##### 1 Answer

This is done by using **Raoult's law**, which states that, for an ideal solution, the partial vapor pressure of a component in that solution is equal to the mole fraction of that component multiplied by its vapor pressure when pure.

If you're dealing with a solution that has a non-volatile solute (a solute that does not have the tendency to form vapor at the temperature of the solution), then the vapor pressure of that solution is

The mole fraction simply refers to ratio between solvent moles and the total number of moles in the solution.

If however you're dealing with a solution that contains a volatile solute, the vapor pressure of that solution is

This equation can be extended to solutions containing three or more components.