What effect does one mole per kilogram H2O of any solute have on vapor pressure?

When a non-volatile solute is dissolved in a solvent, such as water, it results in a phenomenon known as vapor pressure lowering. This occurs because the presence of solute particles reduces the number of solvent molecules at the surface of the liquid that are able to escape into the vapor phase. Specifically, as the solute concentration increases, more solvent molecules are occupied by solute interactions, leading to a decrease in the number of molecules that can vaporize.

In the case of one mole of any solute per kilogram of water, the addition of the solute disrupts the equilibrium between the liquid and vapor phases, resulting in a lower vapor pressure than that of pure water. This is a direct consequence of Raoult's Law, which states that the vapor pressure of a solvent is directly proportional to the mole fraction of the solvent in the solution. Thus, as the mole fraction of the solvent decreases with the addition of the solute, the vapor pressure correspondingly decreases.

This principle is significant in various fields, including chemistry and engineering, where controlling vapor pressure is important in processes such as distillation, where separation of components relies on differences in their vapor pressures.