`NaOH, KOH, Na_2CO_3, K_2CO_3` are easily soluble in water while the corresponding salts of magnesium and calcium are sparingly soluble in water. Explain

Explanation

Alkali metals form monovalent cations (such as `Na^(+), K^(+)`) while alkaline earth metals form divalent cations (such as `Mg^(2+), Ca^(2+)`). Due to increase in charge of the cations, the lattice energy of the corresponding salt increases. For this reason, hydroxides and carbonates of sodium and potassium have lower lattice enthalpy values than the hydroxides and carbonates of magnesium and calcium. As hydration enthalpies of the hydroxides and carbonates of sodium and potassium are greater than their lattice enthalpies, these salts readily dissolve in water. However, in case of the hydroxides and carbonates of calcium and magnesium, the lattice enthalpy values is greater than that of hydration enthalpy and consequently these salts are less soluble in water.