The addition of a nonvolatile solute into a liquid solvent will cause a decrease in the vapor pressure of the solvent. This is because the solute molecules occupy some of the surface area of the solvent and reduce the number of solvent molecules that can escape into the vapor phase. This phenomenon is known as a colligative property of solutions and is related to the number of solute particles. It also results in an increase in the boiling point and a decrease in the freezing point of the solvent, compared to its pure state.
