Question

Dissolving 120g of urea (mol wt 60) in 100 g of water gave solution of density `1.158g//mL`. The molarity of the solution is
A. `1.78 M`
B. `2.00M`
C. `2.05M`
D. `2.22M`

Answer 1

Correct Answer - C
Total mass of solution = (1000+120) = 1120 g
Total volume of solution `= ("Mass")/("Density")=(1120)/(1.15)`
`= 973.91 mL`
Molarity `M_(f)=(W)(m)xx(1000)/(V(mL))`
`=(120)/(60)xx(1000)/(973.91)=2.05 M`