All Enthalpy Definitions

Question 1

Enthalpy change of formation

Answer 1

Enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions

Question 2

Standard conditions

Answer 2

298K at 100kPa

Question 3

Enthalpy change of combustion

Answer 3

Enthalpy change when one mole of a compound undergoes complete combustion in excess oxygen under standard conditions

Question 4

Enthalpy change of neutralisation

Answer 4

Enthalpy change when one mole of water is formed in a reaction between an acid and alkali under standard conditions

Question 5

First ionisation enthalpy (or first ionisation energy)

Answer 5

Enthalpy change when one mole of gaseous atoms loses one mole of electrons to form one mole of gaseous 1+ ions

Question 6

Second ionisation enthalpy (or second ionisation energy)

Answer 6

Enthalpy change when one mole of gaseous 1+ ions loses one mole of electrons to form one mole of gaseous 2+ ions

Question 7

First electron affinity

Answer 7

Enthalpy change when one mole of gaseous atoms gains one mole of electrons to form one mole of gaseous 1- ions

Question 8

Second electron affinity

Answer 8

Enthalpy change when one mole of gaseous 1- ions gains one mole of electrons to form one mole of gaseous 2- ions

Question 9

Enthalpy of atomisation

Answer 9

Enthalpy change when one mole of gaseous atoms is produced from an element under standard conditions

Question 10

Hydration enthalpy

Answer 10

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

Question 11

Enthalpy of solution

Answer 11

Enthalpy change when one mole of ionic solid is dissolved in enough water so that the dissolved ions are well separated and do no interact with each other

Question 12

Bond dissociation enthalpy

Answer 12

Enthalpy change when one mole of covalent bonds in gaseous molecules are broken

Question 13

Lattice enthalpy of formation

Answer 13

Enthalpy change when one mole of solid ionic compound is formed from its constituent gaseous ions

Question 14

Lattice enthalpy of dissociation

Answer 14

Enthalpy change when one mole of solid ionic compound is broken into its constituent gaseous ions

Question 15

Enthalpy of vaporisation

Answer 15

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

Question 16

Enthalpy of fusion

Answer 16

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