Question

The freezing point depression constant \(\left(K_{f}\right)\) of benzene is \(5.12 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\). The freezing point depression for the solution of molality \(0.078 \mathrm{~m}\) containing a non-electrolyte solute in benzene is (rounded off upto two decimal places):
A \(0.20 \mathrm{~K}\)
B \(0.80 \mathrm{~K}\)
(c) \(0.40 \mathrm{~K}\)
D \(0.60 \mathrm{~K}\)

Answer 1

Solution:
\(\Delta T_{f}=i K_{f} m\)
As solute is non-electrolyte, \(i=1\)
\(\Delta T_{f}=1 \times 5.12 \times 0.078\)
\(=0.40 \mathrm{~K}\)