Freezing-Point Depression

Definition

Freezing-point depression describes how adding a solute to a solvent decreases its freezing point below its normal freezing point.

Analogy

Think about road salt being spread on icy roads during winter. The salt (solute) lowers ice's freezing point so it melts even though air temperature might be below water's usual freezing point. This makes roads less slippery just like adding solute makes it harder for our liquid (solvent) to freeze solid!

Related terms

Molality: It’s defined as moles of solute per kilogram of solvent which helps determine how much lower will be new freezing or higher boiling points compared with those pure substances.

Phase Transition: A change from one state (solid, liquid, gas) to another without changing chemical composition.

Supersaturation: A state of a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances. It can also refer to a vapor of a compound that has its (higher) boiling point lowered so it'll condense into solid.