Thermodynamics GapFill

The energy required to separate an ionic solid into its constituent ions in the gas phase, or the energy released in the reverse process, is called the   latticebindingcrystalionic enthalpy. This can be difficult to measure experimentally, so it is often calculated with a   Born−HaberBrønsted−LowryMichelson−MorleyWatson−Crick cycle, which contains enthalpy values that are easier to study. These include the energy released when an electron is added to an atom in the gas phase, called the electron   correspondencecompatibilityactivityaffinity, and the energy required to separate a compound in its standard state into its constituent atoms in the gas phase, called the enthalpy of  vaporisationatomisationdissociationdisintegration.

As well as enthalpy change, the feasibility of a reaction also depends on the entropy change; entropy is a measure of disorder represented by the symbol   WQSE. Together, the enthalpy and entropy changes, along with temperature, determine the   GibbsGoddardGalvaniGoodall free energy change, ΔG, of a process. Only processes for which ΔG  ≤>=<0 are feasible. However, even if a reaction is feasible, it may not take place under standard conditions because of a high  foundationactivationinstigationinitiation energy.