Question

Explain how the addition of a solute affects the vapor pressure of the solvent.

Answer 1

One way is that the solute molecules interact with the solvent molecules. Normally the solvent molecules must overcome the effects of surface tension as well as the forces of neighboring molecules of solvent in order to "jump" from the liquid state to the vapor state. When solute particles are added the molecules must overcome that additional attraction which makes the vapor pressure a little lower.

Answer 2

the molecules water (H2O) and methane (CH4) hav similar masses, but methane changes from a gas to a liquid at -161 degees C. Water becomes a gas at 100 dgrees C. What could account for the difference?