Question

$40$g MgO dissolves in $H_{2}O$ to form $200$ ml of solution, if density of solution is $1.5$g/ml. Calculate the molarity of the solution.

Answer 1

$MgO$ is solute & $H_{2}O$ is solvent

weight of solute $=40g$

volume of solution $=200ml=0.2L$

Moles of solute $=\frac{\text{Weight of solute}}{\text{Molecular weight of solute}}=\frac{40}{40}=1$

Molarity (M) $=\frac{\text{No of moles of solute}}{\text{volume of solution in liters}}=\frac{1}{0.2}=5mole/liter$

$=5M$

Hence, molarity of the solution= $5M$