Alevel Defenitions

Question 1

Enthalphy of formation

Answer 1

Enthalpy change during the formation of 1 mole of a substance from its constituent elements with all substances in their standard states

Question 2

Enthalpy change of combustion

Answer 2

Enthalpy change when one mole of a substance completely burns in oxygen under standard conditions

Question 3

Lattice enthalpy of formation

Answer 3

Enthalpy change when one mole of an ionic compound is formed from gaseous ions under standard conditions

Question 4

First ionisation energy

Answer 4

Energy required to remove one mole of electrons from one mole of gaseous atoms to produce one mole of gaseous ions with charge +1

Question 5

Mean bond enthalpy

Answer 5

Enthalpy change needed to break covalent bonds in gaseous form and different compounds are used

Question 6

Enthalpy of atomisation

Answer 6

Enthalpy change when there is the total separation of atoms in a substance

Question 7

Electron affinity

Answer 7

Enthalpy change when an electron is added to a gaseous atom

Question 8

Enthalpy of hydration

Answer 8

Enthalpy change when an ion is dissolved in water to infinite dilutness