Chemistry Energetics Definitions

Enthalpy of Formation

Enthalpy change when one mole of a substance is formed from its constituent elements, with all substances in their standard states

Enthalpy of Combustion

Enthalpy change when one mole of a substance undergoes complete combustion with an excess of oxygen, with all substances in their standard states

Enthalpy of Neutralisation

Enthalpy change when one mole of water is formed from the reaction between an acid and an alkali, done under standard conditions

1st Ionisation Enthalpy

Enthalpy change when each atom in one mole of gaseous atoms loses an electron, forming one mole of gaseous 1+ ions

2nd Ionisation Enthalpy

Enthalpy change when each atom in one mole of gaseous 1+ ions loses an electron, forming one mole of gaseous 2+ ions

1st Electron Affinity

Enthalpy change when each atom in one mole of gaseous atoms gains an electron, forming one mole of gaseous 1- ions

2nd Electron Affinity

Enthalpy change when each atom in one mole of gaseous 1- ions gains an electron, forming one mole of gaseous 2- ions

Enthalpy of atomisation

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

Hydration Enthalpy

Enthalpy change when one mole of gaseous ions become hydrated (dissolved in water)

Enthalpy of Solution

Enthalpy change when one mole of an ionic solid is dissolved in an amount of water large enough that the dissolved ions are well separated, and do not 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 one mole of a solid ionic compound is formed from its constituent ions in the gaseous state

Lattice Enthalpy of Dissociation

Enthalpy change when one mole of a solid ionic compound is broken down into its constituent ions in the gas phase

Enthalpy of Vaporisation

Enthalpy change when one mole of a liquid is turned into a gas

Enthalpy of Fusion

Enthalpy change when one mole of a solid is turned into a liquid