Question

Arrange the following salts in order from weakest to strongest lattice energy (smallest to largest magnitude of lattice energy): Lithium sulfide, sodium nitrate, potassium nitrate, rubidium sulfide

(1) rubidium sulfide < lithium sulfide < sodium nitrate < potassium nitrate

(2) lithium sulfide < rubidium sulfide < potassium nitrate < sodium nitrate

(3) rubidium sulfide < potassium nitrate < sodium nitrate < lithium sulfide

(4) sodium nitrate < potassium nitrate < rubidium sulfide < lithium sulfide

(5) potassium nitrate < sodium nitrate < rubidium sulfide < lithium sulfide

Answer 1

Smaller the cation higher is the lattice energy and larger the anion higher is the lattice energy.

Li2S - 2472 KJ/mol

NaNO3 - 755 KJ/mol

KNO3 - 694 KJ/mol

Rb2S - 1949 KJ/mol

Hence order is

Li2S > Rb2S > NaNO3 > KNO3

Option (5)