NCERT Solutions for Chapter: Solutions, Exercise 5: Exercises

A solution containing $30 \mathrm{g}$ of non-volatile solute exactly in $90 \mathrm{g}$ of water has a vapour pressure of $2.8 \mathrm{kPa}$ at $298 \mathrm{K}$. Further, $18 \mathrm{g}$ of water is then added to the solution and the new vapour pressure becomes $2.9 \mathrm{kPa}$ at $298 \mathrm{K}$. Calculate the vapour pressure of pure water at $298 \mathrm{K}$.

Henry's law constant for the molality of methane in benzene at $298 \mathrm{K}$is $4.27\times {10}^5 \mathrm{mm} \mathrm{Hg}$. Calculate the solubility of methane in benzene at $298 \mathrm{K}$ under $760 \mathrm{mm} \mathrm{Hg}$.

$100 \mathrm{g}$of liquid $\mathrm{A}$ (molar mass $140 \mathrm{g} {\mathrm{mol}}^{-1}$) was dissolved in $1000 \mathrm{g}$ of liquid $\mathrm{B}$ (molar mass $180 \mathrm{g} {\mathrm{mol}}^{-1}$). The vapour pressure of pure liquid $\mathrm{B}$ was found to be $500 \mathrm{torr}$. Calculate the vapour pressure of pure liquid $\mathrm{A}$ and its vapour pressure in the solution if the total vapour pressure of the solution is $475 \mathrm{Torr}$.

Vapour pressures of pure acetone and chloroform at $328 \mathrm{K}$are $741.8 \mathrm{mm} \mathrm{Hg}$ and $632.8 \mathrm{mm} \mathrm{Hg}$ respectively. Assuming that they form the ideal solution over the entire range of composition, plot ${\mathrm{p}}_{\mathrm{total}}, {\mathrm{p}}_{\mathrm{chloroform}}, \mathrm{and} {\mathrm{p}}_{\mathrm{acetone}}$ as a function of ${\mathrm{x}}_{\mathrm{acetone}}$. The experimental data observed for different compositions of the mixture is : 

Plot this data also on the same graph paper. Indicate whether It has positive deviation or negative deviation from the ideal solution.  

Benzene and Toluene form ideal solution over the entire range of composition. The vapour pressure of pure benzene and toluene at $300 \mathrm{K}$ are $50.71 \mathrm{mm} \mathrm{Hg}$ and $32.06 \mathrm{mm} \mathrm{Hg}$ respectively. Calculate the mole fraction of benzene in vapour phase if $80 \mathrm{g}$ of benzene is mixed with $100 \mathrm{g}$ of toluene. 

The air is a mixture of a number of gases. The major components are oxygen and nitrogen with approximate proportion of $20\%$is to $79\%$ by volume $298 \mathrm{K}$. The water is in equilibrium with air at a pressure of $10 \mathrm{atm}$. At $298 \mathrm{K}$, if the Henry’s law constants for oxygen and nitrogen at$298 \mathrm{K}$ are $3.30\times {10}^7 \mathrm{mm}$ and $6.51 \times {10}^7 \mathrm{mm}$ respectively, calculate the composition of these gases in water.

Determine the amount of ${\mathrm{CaCl}}_2 \left(\mathrm{i}=2.47\right)$ dissolved in $2.5$ litre of water such that its osmotic pressure is $0.75 \mathrm{atm} \mathrm{at} 27°\mathrm{C}$.

Determine the osmotic pressure of a solution prepared by dissolving $25 \mathrm{mg}$ of ${\mathrm{K}}_2{\mathrm{SO}}_4$ in $2$ litre of water at${25}^{\mathrm{o}}\mathrm{C}$, assuming that it is completely dissociated.