Dr. H.C. Srivastava and SUMEDHA SRIVASTAVA Solutions for Chapter: Solutions, Exercise 9: NUMERICAL PROBLEMS

A $1.2\%$ solution of $\mathrm{NaCl}$ is isotonic with $7.2\%$ solution of glucose. Calculate the van't Hoff factor for $\mathrm{NaCl}$.

$2 \mathrm{g}$ of benzoic acid dissolved in $25 \mathrm{g}$ of ${\mathrm{C}}_6{\mathrm{H}}_6$ show a depression in freezing point equal to $1.62 \mathrm{K}$. Molal depression constant of ${\mathrm{C}}_6{\mathrm{H}}_6$ is $4.9 \mathrm{K} {\mathrm{mol}}^{-1}\mathrm{Kg}$. What is the percentage association of acid if it forms double molecules in solution?

$\mathrm{x} \mathrm{g}$ of a non-electrolytic compound (molar mass $=200$) are dissolved in $1.0 \mathrm{L}$ of $0.05 \mathrm{M}$ $\mathrm{NaCl}$ aqueous solution. The osmotic pressure of this solution is found to be $4.92 \mathrm{atm}$ at $27°\mathrm{C}$. Calculate the value of $\mathrm{x}$. Assume complete dissociation of $\mathrm{NaCl}$ and ideal behaviour of the solution $(\mathrm{R}=0.0821 \mathrm{L} \mathrm{atm} {\mathrm{K}}^{-1}{\mathrm{mol}}^{-1})$. 

The degree of dissociation of $\mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2$ in a dilute aqueous solution containing $7.0 \mathrm{g}$ of the salt per $100 \mathrm{g}$ of water at $100°\mathrm{C}$ is $70$ per cent. If the vapour pressure of water at $100°\mathrm{C}$ is $760 \mathrm{mm}$, calculate the vapour pressure of the solution.

Calculate the boiling point of a solution containing $0.61 \mathrm{g}$ of benzoic acid in $50 \mathrm{g}$ of carbon disulphide assuming $84\%$ dimerisation of the acid. The boiling point and ${\mathrm{k}}_{\mathrm{b}}$ of ${\mathrm{CS}}_2$ are $46.2°\mathrm{C}$ and $2.3 \mathrm{K} \mathrm{kg} {\mathrm{mol}}^{-1}$.

How many grams of $\mathrm{KCl}$ should be added to $1.00 \mathrm{kilogram}$ of water to lower its freezing point to $-8.0°\mathrm{C}$? ${\mathrm{K}}_{\mathrm{f}}\left({\mathrm{H}}_2\mathrm{O}\right)=1.88°\mathrm{C} \mathrm{kg} {\mathrm{mol}}^{-1}$ (At. masses : $\mathrm{K}=39, \mathrm{Cl}=35.5$).

Calculate the freezing point of an aqueous solution of a non-electrolyte having an osmotic pressure of $2.0 \mathrm{atm}$ at $300 \mathrm{K}$. 

A solution of a non-volatile solute in water freezes at $-0.30°\mathrm{C}$. The vapour pressure of pure water at $298 \mathrm{K}$is $23.51 \mathrm{mm} \mathrm{Hg}$ and ${\mathrm{K}}_{\mathrm{f}}$ for water is $1.86 \mathrm{degree}/\mathrm{molal}.$ Calculate the vapour pressure of this solution at $298 \mathrm{K}$.