Question

The density of a solution prepared by dissolving 120 g of urea (mol. Mass=60 u) in 1000 g of water is 1.15 g/mL. The molarity if this solution is
A. (a)0.50 M
B. (b)1.78 M
C. (c )1.02 M
D. (d)2.05 M

Answer 1

Correct Answer - D
Total mass of `solution=1000 g water+120 g urea=1120 g`
Density of solution`=1.15 g//mL`
Thus, volume of solution=mass/density`=(1120g)/(1.15 g//mL)`
`=973.91 mL=0.974 L`
Moles of solute`=120/60=2 mol`
`"Molarity"=("moles of solute")/("volume (L) of solution")`
`=(2 "mol")/(0.974 L)=2.05 "mol" L^(-1)`