Question

For which of the following crystalline substances does the solubility in water increase upto ${32}^{\circ }$ and then decrease rapidly?

• A. $CaC{l}_2.2H_{2}O$
• B. $N{a}_{2}S{O}_4.10H_{2}O$
• C. $FeS{O}_4.7H_{2}O$
• D. Alums

Answer 1

Answer: (B)

$N{a}_{2}S{O}_4.10H_{2}O$

For sodium sulphate decahydrate $N{a}_{2}S{O}_4.10H_{2}O$, also known as Glauber's salt, the solubility in water increase upto ${32}^0$C and then decrease rapidly. As thereafter H-bond breaks so solubility decreases rapidly for $N{a}_{2}S{O}_4.10H_{2}O$.