Heat of Formation Definition - Chemistry Glossary

Heat of formation refers to the energy released or absorbed when a pure substance forms from its elements.
Heat of formation refers to the energy released or absorbed when a pure substance forms from its elements.

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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 ΔHf. 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.