Question

If latent heat of fusion of ice is 80 cal per $g$ at $0^{o}C$ , calculate molal depression constant for water:

• A. 18.63
• B. 186.3
• C. 1.863
• D. 0.1863

Answer 1

Answer: (C)

$K_f=\frac{\text{R}{\text{T}}_f^2}{1000\times L_f}$ Here $R=2cals$ ,
$T_f=0+273=273K,L_f=80cals$
$K_f=\frac{2\times 273\times 273}{1000\times 80}=1.863K.kgmo{l}^{-1}$