A solution containing 0.85 g of ZnCl_2 in 12 | vedclass

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

Question

(B) The molar mass of $ZnCl_2$ is $65.3 + 2 	imes 35.5 = 136.3 \ g \ mol^{-1}$.The observed molar mass $(M_{obs})$ is calculated using the depression

Vedclass · Accepted Answer

$73.5 \ \%$

Vedclass · Answer

(B) The molar mass of $ZnCl_2$ is $65.3 + 2 	imes 35.5 = 136.3 \ g \ mol^{-1}$.The observed molar mass $(M_{obs})$ is calculated using the depression in freezing point formula:$\Delta T_f = K_f 	imes \frac{w 	imes 1000}{M_{obs} 	imes W}$$0.23 = 1.86 	imes \frac{0.85 	imes 1000}{M_{obs} 	imes 125}$$M_{obs} = \frac{1.86 	imes 0.85 	imes 1000}{0.23 	imes 125} \approx 55.0 \ g \ mol^{-1}$.The Van't Hoff factor $(i)$ is given by:$i = \frac{M_{normal}}{M_{obs}} = \frac{136.3}{55.0} \approx 2.478$.For the dissociation $ZnCl_2 ightleftharpoons Zn^{2+} + 2Cl^-$,the Van't Hoff factor is $i = 1 + (n-1)\alpha$,where $n=3$.$i = 1 + 2\alpha$.$2.478 = 1 + 2\alpha \implies 2\alpha = 1.478 \implies \alpha = 0.739$.Thus,the degree of dissociation is approximately $73.5 \ \%$.

$A$ solution containing $0.85 \ g$ of $ZnCl_2$ in $125.0 \ g$ of water freezes at $-0.23 \ ^\circ C$. The apparent degree of dissociation of the salt is ($K_f$ for water $= 1.86 \ K \ kg \ mol^{-1}$,atomic mass: $Zn = 65.3$ and $Cl = 35.5$)

Similar Questions

At higher altitude,the boiling point of water is $95\,^oC$. The amount of $NaCl$ added to $1\, kg$ of water $(K_b = 0.52\, K\, kg\, mol^{-1})$ in order to raise the boiling point of the solution to $100\,^oC$ is ......... $g$. (Assuming $90\%$ ionization of $NaCl$)

Which of the following substances shows the highest colligative properties?

The freezing point (in ${}^{\circ}C$) of a solution containing $0.1 \ g$ of $K_3[Fe(CN)_6]$ (Mol. Wt. $329$) in $100 \ g$ of water $(K_f = 1.86 \ K \ kg \ mol^{-1})$ is

The ratio of the value of any colligative property for $KCl$ solution to that for sugar solution is nearly

The freezing point of a $2\%$ aqueous solution of $[Ag(CH_3NH_2)_2]Cl$ is:

Vedclass Test Series

Exam Paper Generator

Online Exam Module