Enthalpy definitions

Enthalpy of formation ΔfH

Enthalpy of formation ΔfH

Enthalpy change when 1 mole of a compound is formed from it’s elements in their standard states under standard conditions.

Bond dissociation enthalpy ΔdissH

Enthalpy change when all the bonds of the same type in 1 mole of gaseous molecules are broken.

Enthalpy of atomisation of an element , ΔatH

Enthalpy change when 1 mole of gaseous atoms is formed from an element in it’s standard state.

Enthalpy of atomisation of a compound, ΔatH

Enthalpy change when 1 mole of a compound in it’s standard state is converted into gaseous atoms.

First ionisation energy Δie1H

Enthalpy change when 1 mole of gaseous 1+ ions is formed from 1 mole of gaseous atoms.

Second ionisation energy, Δie2H

Enthalpy change when 1 mole of gaseous 2+ ions is formed from 1 mole of gaseous 1+ ions.

First electron affinity, Δea1H

Enthalpy change when 1 mole of gaseous 1- ions is formed from 1 mole of gaseous atoms.

First electron affinity, Δea2H

Enthalpy change when 1 mole of gaseous 2- ions is formed from 1 mole of gaseous 1- ions.

Enthalpy of hydration, ΔhydH

Enthalpy change when 1 mole of aqueous ions is formed from 1 mole of gaseous ions

Enthalpy of solution, ΔsolutionH

Enthalpy change when 1 mole of solute is dissolved in enough solvent that no further enthalpy change occurs on further dilution

Enthalpy of lattice formation

enthalpy change when one mole of solid ionic lattice is formed from its gaseous ions.