Skip to main content

Applicable to questions about heat, energy, work, and their interconversion in chemistry. See the tag wiki for a detailed list of topics. Questions tagged may also be tagged with [enthalpy], [energy], [free-energy] where appropriate.

Thermodynamics is the study of various forms of energy in observable systems. As applied to chemical reactions, thermodynamics is used to study and explain the behaviour of chemical reactions in terms of the energy contained within chemical bonds of a substance, and which must be input into or is output from the reaction as a requisite or consequence of the reaction.

The different questions that come under this tag involve one or more of the following:

  • free energy, enthalpy, internal energy or entropy of a gas or their change
  • state and path functions
  • heat capacity
  • expansion and compression processes or their graphical representation
  • various standard enthalpies of reaction (sublimation/neutralization/etc.)
  • spontaneity of a reaction
  • Hess's law/Born-Haber cycle

and other related topics.

Questions about statistical mechanics or "microscopic derivation of thermodynamical laws" invoking thermodynamics are suited for Physics.SE instead.