Distillation is the process by which liquids are purified of impurities. Distillation first requires vaporization of liquids to become pure gases. The gases are then cooled and turned back into pure liquids via condensation into a separate container. A good distillation will remove all impurities from the liquid. This is why distilled water is used for chemical solutions; it does not contain ions or other impurities that could interfere with reaction.

Vaporization refers to the phase change from liquid to gas, also known as evaporation. When becoming a gas, atoms spread out and expand to fill whatever container they are in. Conservation of mass hold that atoms are never created nor destroyed. Atoms becoming more organized and forming a more rigid shape describes a phase change toward becoming solid.