Question

Arrange the following in increasing order of lattice energy:

LiF, LiCl, LiBr, LiI

• A. $LiI<LiBr<LiCl<LiF$
• B. $LiF<LiBr<LiCl<LiI$
• C. $LiF<LiCl<LiBr<LiI$
• D. None of these

Answer 1

The correct option is A $LiI<LiBr<LiCl<LiF$

Lattice Energy is a type of potential energy that may be defined, the lattice energy is the energy required to break apart an ionic solid and convert its component atoms into gaseous ions.

This definition causes the value for the lattice energy to always be positive, since this will always be an endothermic reaction. Its value are usually expressed with the units kJ/mol.
$Latticeenergy\propto \frac{Chargeonion}{sizeoftheion}$

So, the lattice energy of lithium halides (LiF, LiCl, LiBr, Li) will be increased from top to bottom i.e from LiF to LiI due to increase in size of the halides. As the size of the halide increases, it requires more energy to combine them together and releases more energy when they are broken down.

So, the correct order of lattice energy is $LiI<LiBr<LiCl<LiF$