Question

Mole fraction of urea in 900 gram water is 0.05. Density of Solution is 1.2 g/cm³. Find molarity of Solution.

Answer 1

Explanation:

given,

Mole fraction of urea = 900 gram

water = 0.05

The density of Solution = 1.2 g/cm³.

Then Molarity of Solution:

$$\begin{gathered} \mathrm{Number}\mathrm{of}\mathrm{moles}\mathrm{of}\mathrm{H}2\mathrm{O}=\frac{900}{18}=50 \\ \frac{{\mathrm{n}}_1}{({\mathrm{n}}_1+50)}=0.05 \\ ({\mathrm{n}}_1\mathrm{is}\mathrm{No}.\mathrm{of}\mathrm{moles}\mathrm{of}\mathrm{urea}) \\ {\mathrm{n}}_1=2.63 \\ \mathrm{Weight}\mathrm{of}\mathrm{urea}=2.63\times 60=157.8\mathrm{g} \\ \mathrm{Total}\mathrm{weight}=157.8+900=1057.8\mathrm{g} \\ \mathrm{Volume}=\frac{1057.8}{1.2}=881.5\mathrm{cm}3 \\ \mathrm{Molarity}=\frac{2.63}{0.8}=2.99 \end{gathered}$$

Hence, The molarity of the solution is 2.99.