Question

Find the molarity and the normality of a 15% solution by mass of $H_{2}S{O}_4$.
(density of $H_{2}S{O}_4=1.10$ g/mL)

• A. 1.68 M, 3.36 N
• B. 3.36 M, 1.68 N
• C. 0.84 M, 1.68 N
• D. 1.68 M, 0.84 N

Answer 1

The correct option is A 1.68 M, 3.36 N

15% by mass means 15 g of solute in 100 g of solution.
Moles of sulphuric acid = $\frac{\text{given mass}}{\text{molar mass}}=\frac{15}{98}=0.153$

Density = $\frac{\text{mass}}{\text{volume}}$;

So, volume is $\frac{100}{1.1}$ mL
$\text{Molarity}=\frac{\text{moles of solute}}{\text{total volume of solution}}\times 1000=\frac{0.153}{\frac{100}{1.1}}\times 100=1.68M$

Since the n-factor for sulphuric acid is 2, normality = 3.36 N