Heat of Formation Definition - Chemistry Glossary

In chemistry, heat of formation is the heat released or absorbed (enthalpy change) during the formation of a pure substance from its elements at constant pressure (in their standard states). Heat of formation is usually denoted by ΔH_f. It is typically expressed in units of kilojoules per mole (kJ/mol). Heat of formation is also called enthalpy of formation.

The pure substances in question may be elements or compounds. However, the heat of formation of a pure element has a value of 0.

Sources

• Kleykamp, H. (1998). "Gibbs Energy of Formation of SiC: A contribution to the Thermodynamic Stability of the Modifications". Berichte der Bunsengesellschaft für physikalische Chemie. pp. 1231–1234.
• Zumdahl, Steven (2009). Chemical Principles (6th ed.). Boston. New York: Houghton Mifflin. pp. 384–387. ISBN 978-0-547-19626-8.