Question

Equimolal aqueous solutions of $ NaCl $ and $ BaCl_{2} $ are prepared. If the freezing point of $ NaCl $ is $ -2^{\circ}C $ , the freezing point of $ BaCl_{2} $ solution is expected to be

• A. $ -2^{\circ}C $
• B. $ -3^{\circ}C $
• C. $ -1.5^{\circ}C $
• D. $ -1.66^{\circ}C $

Answer 1

Answer: (B)

$i=N a C l=2$,
$i$ for $B a C l_{2}=3$
Hence, $\frac{\Delta T_{f}(N a C l)}{\Delta T_{f}\left(B a C l_{2}\right)}=\frac{2}{3}$
or $T_{f}\left(B a C l_{2}\right)=\frac{3}{2} \times 2=3^{\circ}$
$\left.\left(\Delta T_{f} N a C l\right)=2\right)$
So that $T_{f}$ for $Ba$
$B a C l_{2}=-3^{\circ} C$