Question

Find mass % of 10 m of aqueous solution of urea. If molar mass of urea is 60 g/mol and density of solution is 1.2 $g{cm}^{-3}$.

Answer 1

We have,

molality of urea solution = 10m

that means,

1000g of water contain urea = 10 moles = $10\ast 60=600g$ of urea

so, mass of solution = $solute+solvent=1000+600=1600g$

so, $mass$ = $\frac{massofsolute}{massofsolution}\ast 100=\frac{600}{1600}\ast 100=37.5$