temperature or pressure change. Phase diagrams for real solutions show how
azeotropes and eutectics can’t be avoided.
Colligative properties address the changes in the physical properties of the
solution with respect to the major component—the solvent. Raoult’s law sum-
marizes the change in the vapor pressure of a volatile solvent. Freezing points
and boiling points change. But osmotic pressure may be the most underrated
colligative property. It is a factor in biological cells and our ability to make
fresh water from seawater. Luckily, the equations of thermodynamics provide
an understanding of all of these phenomena.202 CHAPTER 7 Equilibria in Multiple-Component Systems