When a liquid is cooled, the average energy of the molecules decreases.

At some point, the amount of heat removed is great enough that the attractive forces between molecules draw the molecules close together, and the liquid freezes to a solid.

Microscopic view of a liquid. Microscopic view of a solid.

The temperature of a freezing liquid remains constant, even when more heat is removed.

The freezing point of a liquid or the melting point of a solid is the temperature at which the solid and liquid phases are in equilibrium.

The rate of freezing of the liquid is equal to the rate of melting of the solid and the quantities of solid and liquid remain constant.

Factors That Affect Freezing Point