A 5% solution (by mass) of cane sugar in wate | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(C) The depression in freezing point is given by $\Delta T_f = K_f 	imes m$,where $m$ is the molality.For a $5\%$ solution (by mass),the molality $m

Vedclass · Accepted Answer

$269.07$

Vedclass · Answer

(C) The depression in freezing point is given by $\Delta T_f = K_f 	imes m$,where $m$ is the molality.For a $5\%$ solution (by mass),the molality $m = \frac{w_2 	imes 1000}{M_2 	imes w_1}$.Since the percentage by mass is the same $(5\%)$,the molality is inversely proportional to the molar mass $(M_2)$ of the solute.$\Delta T_f \propto \frac{1}{M_2}$.For cane sugar $(M_1 = 342 \ g/mol)$: $\Delta T_{f1} = 273.15 - 271 = 2.15 \ K$.For glucose $(M_2 = 180 \ g/mol)$: $\Delta T_{f2} = \Delta T_{f1} 	imes \frac{M_1}{M_2}$.$\Delta T_{f2} = 2.15 	imes \frac{342}{180} = 2.15 	imes 1.9 = 4.085 \ K$.The freezing point of the glucose solution $= 273.15 - 4.085 = 269.065 \ K \approx 269.07 \ K$.

$A$ $5\%$ solution (by mass) of cane sugar in water has a freezing point of $271 \ K$ and the freezing point of pure water is $273.15 \ K$. The freezing point of a $5\%$ solution (by mass) of glucose in water is ............. $K$.

Similar Questions

The freezing point of an aqueous solution containing $17 \ g$ of $C_2H_5OH$ in $1000 \ g$ of water is ......... $^oC$. (Given $K_f$ of water $= 1.86 \ K \ kg \ mol^{-1}$)

Freezing point of a $4 \%$ aqueous solution of $X$ is equal to the freezing point of a $12 \%$ aqueous solution of $Y$. If the molecular weight of $X$ is $A$,then the molecular weight of $Y$ is ............. $A$.

$1\%$ solution of $Ca(NO_3)_2$ has a freezing point:

What is the molar mass of a solute when $5 \ g$ of solute dissolved in $70 \ g$ of solvent lowers its freezing point by $2.5 \ K$? Given $K_f = 3.5 \ K \ kg \ mol^{-1}$.

How many grams of methyl alcohol should be added to a $10 \, L$ tank of water to prevent its freezing at $268 \, K$? ($K_f$ for water is $1.86 \, K \, kg \, mol^{-1}$,density of water is $1 \, kg/L$)

Vedclass Test Series

Exam Paper Generator

Online Exam Module