Discussion Forum



1)

Dissolving 120 g of urea (molecular weight 60) in 1000 g of water gave a solution of density 1.15 g /mL. The molarity of the solution is


A) 1.78 M

B) 2.00M

C) 2.05M

D) 2.22 M

Answer:

Option C

Explanation:

 Molarity = Moles  of solute/Volume of solution(L)

Moles of urea= $\frac{120}{60}=2$

weight of solution =weight  of solvent+weight of solute=1000+120=1120g

$\Rightarrow$  Volume =$\frac{1120g}{1.15 g/mL} \times \frac{1}{1000mL/L}=0.974 L \Rightarrow  Molarity=\frac{2000}{0.974}=2.05M$