Energetics or thermochemistry (a branch of thermodynamics) is the study of the movement of heat energy (called enthalpy) in chemistry. Changes in enthalpy and entropy (a measure of the number of ways of arranging energy in a substance) can be used to accurately predict the outcome of chemical reactions.

  • Bond enthalpies

    Topic 5.3 Bond enthalpy values can be used to estimate enthalpy changes.

  • Energy cycles

    15.1 Born Haber cycles are used to calculate lattice enthalpies for ionic compounds.

  • Entropy and spontaneity

    15.2 Entropy and Gibb's Free Energy allow us to predict if reactions are spontaneous (allowed).

  • Hess's Law

    Topic 5.2 Hess's Law allows us to measure enthalpy changes indirectly.

  • Measuring energy changes

    Topic 5.1 Enthalpy is heat energy (at constant pressure) and we can measure enthalpy changes using ΔH=mcΔT.