Dr. H.C. Srivastava and SUMEDHA SRIVASTAVA Solutions for Chapter: Solutions, Exercise 10: QUESTIONS FROM ISC EXAMINATION PAPERS

Why the freezing point depression ($∆{\mathrm{T}}_{\mathrm{f}}$) of 0.4 M NaCl solution is nearly twice than that of 0.4 M glucose solution?

Determine the freezing point of a solution containing $0.625 \mathrm{g}$ of glucose (${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$) dissolved in $102.8 \mathrm{g}$ of water. (Freezing point of water = $273 \mathrm{K}$, K_f for water $= 1.87 \mathrm{K}·\mathrm{kg}·{\mathrm{mol}}^{-1}$, at. wt. $\mathrm{C} = 12, \mathrm{H} = 1, \mathrm{O} = 16$)

A $0.15 \mathrm{M}$ aqueous solution of KCI exerts an osmotic pressure of $6.8 \mathrm{atm}.$ at $310 \mathrm{K}$. Calculate the degree of dissociation of $\mathrm{KCl}$. ($\mathrm{R}=0.0821 \mathrm{L}·\mathrm{atm}·{\mathrm{K}}^{-1}·{\mathrm{mol}}^{-1}$).

A solution containing $8.44 \mathrm{g}$ of sucrose in $100 \mathrm{g}$ of water has a vapour pressure $4.56 \mathrm{mm}$ of $\mathrm{Hg}$ at $273 \mathrm{K}$. If the vapour pressure of pure water is $4.58 \mathrm{mm}$ of $\mathrm{Hg}$ at the same temperature, calculate the molecular weight of sucrose.

An aqueous solution of urea freezes at $-0.186°\mathrm{C}$, K_f for water $= 1.86 \mathrm{K}·\mathrm{Kg}·{\mathrm{mol}}^{-1}$, K_b for water $= 0.512 \mathrm{K}·\mathrm{Kg}·{\mathrm{mol}}^{-1}$. The boiling point of urea solution will be.

Calculate the osmotic pressure of a solution prepared by dissolving $0.025 \mathrm{g}$ of ${\mathrm{K}}_2{\mathrm{SO}}_4$ in $2.0$ litres of water at $25 °\mathrm{C}$, assuming that ${\mathrm{K}}_2{\mathrm{SO}}_4$ is completely dissociated. (mol wt. of ${\mathrm{K}}_2{\mathrm{SO}}_4=174 \mathrm{g}·{\mathrm{mol}}^{-1}$).

An aqueous solution containing $12.48 \mathrm{g}$ of barium chloride (${\mathrm{BaCl}}_2$) in $1000 \mathrm{g}$ of water, boils at $100.0832°\mathrm{C}$. Calculate the degree of dissociation of barium chloride. (K_b for water $= 0.52 \mathrm{K}·\mathrm{kg}·{\mathrm{mol}}^{-1}$, at. wt. $\mathrm{Ba} = 137, \mathrm{Cl} = 35.5$)

The freezing point of a solution containing $5.85 \mathrm{g}$ of $\mathrm{NaCl}$ in $100 \mathrm{g}$ of water is $-3·{348}^{\mathrm{o}}\mathrm{C}$. Calculate van’t Hoff factor ‘$\mathrm{i}$’ for this solution. What will be the experimental molecular weight of $\mathrm{NaCl}$? (${\mathrm{K}}_{\mathrm{f}}$ for water $= 1·86 \mathrm{K}·\mathrm{kg}·{\mathrm{mol}}^{-1}$, at. wt. $\mathrm{Na} = 23, \mathrm{Cl} = 35.5$)