13A Lattice Energy (Energetics II)

Question 1

Lattice Energy

Answer 1

The energy change when one mole of an ionic solid /compound is formed from its gaseous ions under standard conditions.
X+(g) + Y-(g) —> XY (s)

Question 2

Enthalpy change of atomisation, AatH

Answer 2

The energy required for the formation of one mole of gaseous atoms of an element.

Question 3

Electron affinity, AeaH

Answer 3

Each atom of gaseous atoms gains one electron to form one mole of gaseous 1- ions.
First = exothermic
Second+ = endothermic (same polarity)

Question 4

Enthalpy change of formation, AfH

Answer 4

One mole of compound is formed from its elements under standard conditions.

Question 5

Ionisation Energy

Answer 5

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous ions.

Question 6

Enthalpy change of solution, AsolH

Answer 6

One mole of a compound is dissolved to form an indefinitely dilute solution.
(Further addition of water causes no additional energy change)

Question 7

Enthalpy change of hydration, AhydH

Answer 7

One mole of gaseous ions dissolve in water to give an indefinitely dilute solution.
Always exothermic (bonds formed)

Question 14

Standard conditions

Answer 14

298K, 100kPa

Question 15

Lattice formation enthalpy

Answer 15

The energy required to firm an ionic lattice from its constituent ions in a gaseous state under standard conditions.

Question 16

Lattice dissociation enthalpy, AleH

Answer 16

Energy required to break apart an ionic lattice into its constituent ions in a gaseous state under standard conditions.