Enthalpy Defenitions

Question 1

Enthalpy of formation

Answer 1

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

Question 2

Enthalpy of combustion

Answer 2

Enthalpy change when one mole of a substance is completely combusted in oxygen with all substances in standard states.

Question 3

Enthalpy of neutralisation

Answer 3

Enthalpy change when one mole of water is formed from an acid and alkali under standard conditions (25C and 100KPa)

Question 4

First ionisation energy

Answer 4

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

Question 5

Second ionisation energy

Answer 5

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

Question 6

First electron affinity

Answer 6

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

Question 7

Second electron affinity

Answer 7

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

Question 8

Enthalpy of atomisation

Answer 8

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

Question 9

Hydration enthalpy

Answer 9

Enthalpy change when one mole of gaseous ions become hydrated

Question 10

Enthalpy of solution

Answer 10

Enthalpy change when one mole of an ionic solid dissolves in water large enough so that it’s ions are well separated and not interact with each other

Question 11

Bond dissociation enthalpy

Answer 11

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

Question 12

Lattice Enthalpy of formation

Answer 12

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

Question 13

Lattice enthalpy of dissociation

Answer 13

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

Question 14

Enthalpy of vaporisation

Answer 14

Enthalpy change when one mole of liquid is turned into gas

Question 15

Enthalpy of fusion

Answer 15

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