Thermodynamics Definitions (A2)

Question 1

Enthalpy of Formation

Answer 1

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

Question 2

Enthalpy of Combustion

Answer 2

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

Question 3

First ionisation energy

Answer 3

Enthalpy change when one mole of gaseous atoms loses one electron per atom to produce gaseous 1+ ions

Question 4

Second ionisation energy

Answer 4

Enthalpy change when one mole of gaseous 2+ ions is produced from 1+ ions

Question 5

First electron affinity

Answer 5

Enthalpy change when one mole of gaseous atoms gains one electron per atom to produce gaseous 1- ions

Question 6

Second electron affinity

Answer 6

Enthalpy change when one mole of gaseous 1- ions gains one electron per ion to produce 2- ions

Question 7

Enthalpy of atomisation of an element

Answer 7

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

Question 8

Hydration enthalpy

Answer 8

Enthalpy change when one mole of gaseous ions become hydrated

Question 9

Enthalpy of solution

Answer 9

Enthalpy change when one mole of an ionic solid dissolves in an amount of water large enough so that the dissolved ions are well separated and do not interact with each other

Question 10

Bond dissociation enthalpy

Answer 10

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

Question 11

Lattice enthalpy of formation

Answer 11

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

Question 12

Lattice enthalpy dissociation

Answer 12

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

Question 13

Enthalpy atomisation of a compound

Answer 13

Enthalpy change when 1 mole of a compound in it standard state is converted to gaseous atoms