Define Vapor-pressure lowering and Osmotic pressure?

1. Vapor-pressure lowering: the decrease in the vapor pressure of a solution containing nonvolatile solutes, compared to the vapor pressure of the pure solvent at the same temperature.

2. Osmotic pressure: the increase in the pressure of the solution that places the solvent in transfer equilibrium with pure solvent at the same temperature and pressure as the original solution.

Note that all four properties are defined by an equilibrium between the liquid solution and a solid, liquid, or gas phase of the pure solvent. The properties called colligative (Latin: tied together) have in common a dependence on the concentration of solute particles that affects the solvent chemical potential.