Question

The correct order of lattice energy order is:

• A. $LiF>LiCl>LiBr>LiI$
• B. $LiCl>LiF>LiBr>LiI$
• C. $LiBr>LiCl>LiF>LiI$
• D. $LiI>LiBr>LiCl>LiF$

Answer 1

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

We know that the lattice energy is directly proportional to the product of the charges of the ions and inversely proportional to the separation between the centres of the ions, i.e., the size of the ions.
Since all the compounds have the same cation, i.e., $L{i}^{+}$, the size of the anions will be considered.
Down the group, size increases, i.e., $F^{-}<C{l}^{-}<B{r}^{-}<I^{-}$
Thus, the correct order of lattice energy is:
$LiF>LiCl>LiBr>LiI$