Question

THE HYDROXIDES AND CARBONATE ,Na,K, R EASILY SOLUBLE IN H2O WHILE THE CORRESPONDING SALT OF Mg AND ca R SPARINGLY SOLUBLE IN H2O

Answer 1

Mg and Ca hydroxides, the cationic radius are smaller than Na and K which will influence the lattice enthalpy. Due to this they have high lattice enthalpy and lower hydration enthalpy compared to Na and K, so they have lesser solubility.

The hydration enthalpies is lesser for Mg and Ca as compared to Na and K, hence their carbonates have lower solubility.

Note:

• Hydration enthalpy increases solubility while lattice enthalpy decreases solubilty
• Smaller radius of cation increases lattice enthalpy.