A2 Thermodynamics - Born-Haber Cycle Definitions (also includes Enthalpy of Solution and Enthalpy of Hydration

Question 1

Enthalpy of formation

Answer 1

Enthalpy change when 1 mole of a compound is formed from its constituent element in their standard states under standard conditions.

Question 2

Enthalpy of atomisation

Answer 2

Enthalpy change to produce 1 mole of gaseous atoms from elements in standard conditions under standard states

Mg (s) ➡️ Mg (g)

1/2 Cl2 (g) ➡️ Cl (g)

Question 3

Enthalpy of 1st Ionisation

Answer 3

Enthalpy change to remove 1 mole of electrons from 1 mole of gaseous atoms.

Na (g) ➡️ Na+ + e-

Question 4

Enthalpy of 2nd Ionisation

Answer 4

Enthalpy change when 1 mole of electrons is removed from 1 mole of gaseous ions.

Mg+ (g) ➡️ Mg2+ + e-

Question 5

Enthalpy of 1st Electron Affinity

Answer 5

Enthalpy change to add 1 mole of electrons to 1 mole of gaseous atoms.

Cl (g) + e- ➡️ Cl- (g)

Question 6

Enthalpy of 2nd electron affinity

Answer 6

Enthalpy change to add 1 mole of electrons to 1 mole of gaseous ions.

O- (g) + e- ➡️ O2- (g)

Question 7

Lattice Enthalpy of formation

Answer 7

Enthalpy change to form 1 mole of a solid ionic compound from its constituent gaseous ions
H
Cl- (g)+ Na+ (g)➡️ NaCl (g)

Question 8

Bond Enthalpy

Answer 8

Enthalpy change required to break 1 mole of gaseous covalent bonds.

Question 9

Lattice Enthalpy of dissociation

Answer 9

The enthalpy change when 1 mole of a solid ionic lattice dissociates into isolated gaseous ions.

Question 10

Enthalpy of Solution

Answer 10

Enthalpy change when 1 mole of a solid ionic compound completely dissolves in enough water to separate the ions.

NaCl (s) ➡️ Na+ (aq) + Cl- (aq)

Question 11

Enthalpy of Hydration

Answer 11

Enthalpy change when 1 mole of gaseous ions is dissolved into one mole of aqueous ions.

Na+ (g) + Cl- (g) ➡️ Na+ (aq) + Cl- (aq)

Question 12

Bond dissociation enthalpy

Answer 12

Enthalpy change to break the bond in 1 mol of molecules
To form gaseous atoms