Question

Which of the following will have maximum depression in freezing point?

• A. $0.5ML{i}_{2}S{O}_4$
• B. $1MKCl$
• C. $0.5MA{l}_2(S{O}_4{)}_3$
• D. $0.5MBaC{l}_2$

Answer 1

The correct option is C $0.5MA{l}_2(S{O}_4{)}_3$

The depression in freezing point is a colligative property and it is dependent on the number of solute ions present in the given solution.

$1M$ $KCl$ gives two ions on dissociation in its solution which is $K^{+}$ and $C{l}^{-}$ ions.

$0.5MA{l}_2(S{O}_4{)}_3$ on dissociation gives two ions which are $A{l}^{3+}$ and $S{O}_4^{2-}$

$BaC{l}_2\rightleftharpoons B{a}^{2+}+2C{l}^{-}$ ( three ions in $0.5M$)

$L{i}_{2}S{O}_4\rightleftharpoons 2L{i}^{+}+S{O}_4^{2-}$ (three ions in $0.5M$)

Here $1M$ $KCl$ gives two ions in $1M$ solution. Thus the depression in freezing point is maximum for $1MKCl$.