Question

Dissolving `120g` of urea `(Mw = 60)` in `1000 g` of water gave a solution of density `1.15 g mL^(-1)`. The molarity of solution is:
A. 1.78 M
B. 2.00 M
C. 2.05 M
D. 2.22 M

Answer 1

Correct Answer - C
Total mass of the solution = 1000 + 120 = 1120g
Total volume of the solution = 1120/1.15 mL
`= 1120/1.15 xx 10^(-3) L = 1.12/1.15 L`
`120 g "urea" = 120/60 "mol" = 2"mol"`
`"Molarity"=(2 "mol")/((1.12 //1.15)L)= (2 xx 1.15)/1.12 "mol"^(-1)`