91Ó°ÊÓ

Vapour pressure may be defined as the pressure when the liquid and vapour are at equilibrium. The equilibrium force per unit area is understood to function an indicator of the evaporation rate of a liquid.

Mass of Non-Electrolyte= 12.0g

Molar Mass of Non-Electrolyte= x g/mole

Mass of Water= 80g= 0.80g

Molar Mass of Water= 18 g/mole

Firstly,

\(\begin{align}Molality &= \frac{{Number\,of\,moles}}{{Mass\,of\,Solvent(kg)}}\\Molality &= \frac{{12/x}}{{0.080}}\end{align}\)

\({\bf{\Delta Tfreezing = i \times Kf \times m}}\)

Vapour Pressure of Solution= 23.35 Tor

\({{\bf{k}}_{\bf{f}}}\)value of Water= 1.86

\(\begin{align}\Delta Tf &= i \times Kf \times m\\0 - Tf &= 1 \times 1.86 \times \frac{{12/x}}{{0.080}}\\0 - ( - 1.94) &= 1.86 \times \frac{{12/x}}{{0.080}}\\1.94/1.86 &= \frac{{12/x}}{{0.080}}\\1.043 \times 0.080 &= 12/x\\x &= \frac{{12 \times 1.043}}{{0.080}}\\x &= 144g/mole\end{align}\)

The Molar Mass of Non-Electrolyte=144 g/mole