Question

Dissolving 120 gram of urea in thousand gram of the water give a solution of density 1.15 gram per ml the molarity of the solution is

Answer 1

Answer: 2.05 M

Explanation: Molarity : It is defined as the number of moles of solute present per liter of solution.

Formula used :

$Molarity=\frac{n\times 1000}{V_s}$

where,

n= moles of solute

$Moles=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{120g}{60g/mol}=2moles$  

Mass of solute (urea) = 120

Mass of solvent (water)= 1000 g

Mas of solution= mass of solute + mass of solvent = 1120 g

$V_s$ = volume of solution in ml=$\frac{\text {mass of solution}}{\text {Density of solution}}=\frac{1120g}{1.15g/ml}= 974ml$

Now put all the given values in the formula of molarity, we get

$Molarity=\frac{2moles\times 1000}{974ml}=2.05M$

Therefore, the molarity of solution will be 2.05 M