Enthalpy definitions.

Enthalpy of formation.

The enthalpy change when one mole of a compound is formed from its elements in their standard states.

Enthalpy of combustion

The enthalpy change when one mole of a substance undergoes complete combustion with oxygen under standard conditions and with all substances in their standard states.

Enthalpy of neutralization

Enthalpy change when 1 mole of a water is formed in a reaction between an acid and an alkali under standard conditions and all substances are in their standard states.

Ionisation Enthalpy (1st)

Enthalpy change when each atom in one mole of gaseous atoms loses 1 electron to form one mole of gaseous 1+ cations in their gaseous state.

Ionisation Enthalpy (2nd)

Enthalpy change when each atom in one mole of gaseous +1 ions loses 1 electron to form one mole of gaseous 2+ cations in their gaseous state.

Electron Affinity (1st)

Enthalpy change when each atom in one mole of gaseous atoms gains 1 electron to form one mole of gaseous 1- anions in their gaseous state.

Electron Affinity (2nd)

Enthalpy change when each atom in one mole of gaseous 1- anions gains 1 electron to form one mole of gaseous 2- anions in their gaseous state.

Enthalpy of Atomisation

Enthalpy change when one mole of gaseous atoms are produced from an element in its standard state.

Hydration Enthalpy

Enthalpy change when one mole of gaseous ions is dissolved in water.

Enthalpy of Solution

Enthalpy change when 1 mole of an ionic solid dissolves in an amount of water large enough so that the dissolved ions are separated enough not to interact with each other.

Bond dissociation Enthalpy

Enthalpy change when one mole of covalent bonds is broken in the gaseous state.

Lattice Enthalpy of formation

Enthalpy change when 1 mole of a solid ionic compound is formed from its constituent ions in the gas phase.

Lattice Enthalpy of dissociation.

Enthalpy change When 1 mole of its solid ionic compound is broken up into its constituent elements in the gas phase.

Enthalpy of vapourisation

Enthalpy change when 1 mole of liquid is turned into gas.

Enthalpy of Fusion

Enthalpy change when 1 mole of a solid is turned into a liquid.