Question

The melting points for the compounds li2s, rb2s, and k2s are 900°c, 530°c, and 840°c, respectively. list these three compounds in order of increasing lattice energy.

Answer 1

Answer: The order of increasing lattice energy is $Li_2S>K_2S>Rb_2S$

Explanation: Lattice energy is defined as the energy required to break the intermolecular force that is responsible for the formation of a lattice.

Melting point is defined as the temperature at which solid gets converted into liquid due to the weakening of the bonds in the solid form.

• Relation between lattice energy and Melting point:

The relationship between these two is direct.

$\text{Lattice energy}\propto \text{Melting point}$

More the melting point of a compound, more will be its lattice energy.

Order of increasing Lattice energy will be:

$Li_2S>K_2S>Rb_2S$