Question

The lattice energies of $NaCl,NaF,KCl$ and $RbCl$ follow the order:

• A. $KCl<RbCl<NaCl<NaF$
• B. $NaF<NaCl<KCl<RbCl$
• C. $RbCl<KCl<NaCl<NaF$
• D. $NaCl<RbCl<NaF<KCl$

Answer 1

The correct option is C $RbCl<KCl<NaCl<NaF$

Lattice energy is directly proportional to charge of the ion and size of ions.Lattice energy is inversely proportional to size of ion.

As $F^{-}$ is smaller in size than $C{l}^{-}$ so $NaF$ has greater lattice energy than $NaCl$ and as $N{a}^{+}$ is smaller in size than $K^{+}$ so $NaCl$ has greater lattice energy than $KCl$.

So $RbCl<KCl<NaCl<NaF$.