Question

What will be the freezing point of $1\%$ solution of glucose in water, given that molal depression constant for water is $1.84Kmo{l}^{-1}$

• A. $272.898K$
• B. $0.102{}^{\circ }C$
• C. $273K$
• D. $108{}^{\circ }C$

Answer 1

Answer: (A)

Mass of solution $=100g$
Mass of glucose $=1g$
Mass of solvent $=100-1=99g$
$w=$ mass of solute glucose,
$W=$ mass of solvent $m=$ molar mass of solute
$\Delta T_f\times \frac{w}{m}\times \frac{1}{W/1000}$
$=1.84\times \frac{1}{180}\times \frac{1}{99/1000}=0.103$
Freezing point of the solution $=273-0.103$
$=272.897K$