Question

$0.1M$ aqueous solution of $K_4\left[Fe(CN{)}_6\right]$ will have the same freezing point as $0.1M$ aqueous solution of

• A. $Fe{\left(S{O}_4\right)}_3$
• B. $A{l}_2{\left(S{O}_4\right)}_3$
• C. $AlC{l}_3$
• D. $K_{3}P{O}_4$

Answer 1

Answer: (B)

$0.1M{K}_4\left[Fe(CN{)}_6\right]⟶4K^{+}+{\left[Fe(CN{)}_6\right]}^{-4}\Delta T_f=i\left(K_f\times m\right)i=5$
(1) $\underset{0.1M}{Fe{\left(S{O}_4\right)}_3}⟶F{e}^{2+}+3S{O}_4^{2-}(i=4)$
(2) $A{l}_2{\left(S{O}_4\right)}_3⟶2A{l}^{3+}+3S{O}_4^{2-}(i=5)$
(3) $AlC{l}_3⟶A{l}^{3+}+3C{l}^{-}(i=4)$
(4) $K_{3}P{O}_4⟶3K^{+}+P{O}_4{}^{3-}(i=4)$
If $i=$ same
$T_f=$ same
$T_f\propto i$
for same concentration