Ch4 Lattice enthalpy

Question 1

Ionic charge affect on lattice enthalpy

Answer 1

as charge increases,
- lattice enthalpy more exothermic
- more energy is released when lattice is formed
- more energy required to break lattice

Question 2

Lattice enthalpy

Answer 2

energy released when 1 mol of an ionic compound is formed from its constituent ions ins their gaseous state under standard conditions

Question 3

Ionic radius affect on lattice enthalpy

Answer 3

as radius decreases
- smaller ions form stronger lattices as force of attraction is higher
- lattice enthalpy more exothermic

Question 4

Polarisation

Answer 4

distortion of electron cloud in molecule or ion by nearby positive charge

Question 5

polarising power of cation

Answer 5

increase as charge increases
increases as radius decreases

Question 6

polarizability of anion

Answer 6

increases as radius increases
- outermost electron further from attraction of positive nucleus so lost more easily

Question 7

Enthalpy change of atomisation

Answer 7

enthalpy change when 1 mol of gaseous ions is formed from element in standard state

Question 8

stability of ionic compound

Answer 8

more exothermic the enthalpy change of formation, the more stable
- compounds in lower energy level
- more stable than elements

Question 9

First electron affinity

Answer 9

enthalpy change when 1 mol of gaseous atoms gains 1 mol of electrons

Question 10

born haber cycle

Answer 10

total enthalpy change for atomising and ionising elements + lattice enthalpy = enthalpy change of formation