Phase changes-Vocabulary

Phase change

A change in the state of matter of a substance. A phase change is an example of a physical change.

Heat of Vaporization

The energy required to change an amount of substance from the liquid to the gaseous state. The temperature during this phase change remains constant.

Endothermic Change

A chemical reaction that is accompanied by the absorption of heat. A chemical reaction that works only if heat is absorbed is an example of a reaction that would be described as endothermic.

Boiling

A phase transition from the liquid state to the gas state, usually occurring when a liquid is heated to its boiling point.

Exothermic Change

An exothermic reaction is a chemical reaction that releases energy by light or heat. It is the opposite of an endothermic reaction.

Deposition

Deposition refers to the phase change from gas to solid. The process where a gas changes phase and turns directly into a solid without passing through the liquid phase.

Sublimation

Sublimation is the term for when matter undergoes a phase transition directly from a solid to gaseous form, or vapor, without passing through the more common liquid phase between the two.

Heat of Fusion

The change in enthalpy for the conversion of 1 mole or 1 gram of a solid to a liquid, at constant pressure and temperature and is usually denoted as ΔHfus.

Condensation

The change in the state of matter from the gas phase to the liquid phase.

Vaporization

The phase transition of a substance from the liquid phase to the gas phase.

Melting

The process by which a substance changes from the solid phase to the liquid phase.

Evaporation

The process by which molecules undergo the a spontaneous transition from the liquid phase to the gas phase. Evaporation is the opposite of condensation.

Freezing

The process through which a substance changes from a liquid to a solid. All liquids except helium undergo freezing when the temperature becomes sufficiently cold.