Question

What is the mass of a non volatile solute (molecular mass 60) that needs tobe dissolved in $100g$ of water In order to decrease the vapour pressure of water by $25$.What will be the velocity of solution?

Answer 1

Given that $P^o=100,P=25,M=60,W=100,M{H}_{2}O=18$ .

$\Rightarrow \frac{P^o-P}{P^o}=\frac{W}{m}\times \frac{M}{W}$

$\Rightarrow \frac{100-25}{100}=\frac{W}{60}\times \frac{18}{100}$

$W=250gm$

Molality= $\frac{\text{Mole of solute}}{\text{Weight of solvent}}$

$=\frac{250\times 1000}{60\times 1000}=41.66m$ .