Question

The correct increasing order of the lattice energy of alkali metal carbonates is:

• A. $C{s}_{2}C{O}_3<R{b}_{2}C{O}_3<K_{2}C{O}_3<N{a}_{2}C{O}_3<L{i}_{2}C{O}_3$
• B. $R{b}_{2}C{O}_3<C{s}_{2}C{O}_3<K_{2}C{O}_3<L{i}_{2}C{O}_3<N{a}_{2}C{O}_3$
• C. $L{i}_{2}C{O}_3<N{a}_{2}C{O}_3<K_{2}C{O}_3<R{b}_{2}C{O}_3<C{s}_{2}C{O}_3$
• D. None of these

Answer 1

The correct option is A $C{s}_{2}C{O}_3<R{b}_{2}C{O}_3<K_{2}C{O}_3<N{a}_{2}C{O}_3<L{i}_{2}C{O}_3$

Lattice energy is defined as the energy required to separate a mole of an ionic solid into gaseous ions. Lattice energy cannot be measured empirically, but it can be calculated using electrostatics or estimated using the Born-Haber cycle
Lattice energy of carbonates of a particular group decreases due to increase in atomic size, it requires less energy to separate the solid crystal into its gaseous ions., so the lattice energy decreases from Li to Cs.

So, the correct order of lattice energy of carbonates of IA group elements is:

$C{s}_{2}C{O}_3<R{b}_{2}C{O}_3<K_{2}C{O}_3<N{a}_{2}C{O}_3<L{i}_{2}C{O}_3$

Hence, option A is correct.