Question

A solution of 36.5% $HCl$ by mass has a density of 1.20 g mL${}^{-1}$. The molarity and normality of the solution respectively are:

• A. 12 M, 12 N
• B. b. 6 M, 6 N
• C. 6 M,12 N
• D. 12 M,6 N

Answer 1

The correct option is A 12 M, 12 N

Let the total mass of solution be 100 g.
36.5% by mass means 36.5 g of $HCl$ is present in 100 g of the solution.
Moles of HCl =$\frac{36.5}{36.5}=1$ mol

Density = $\frac{\text{mass}}{\text{volume}}$; volume is calculated as $\frac{100}{1.2}$ mL

Molarity = $\frac{\text{moles of solute}}{\text{total volume of solution in mL}}\times 1000=\frac{1}{\frac{100}{1.2}}\times 1000=12M$

Since n-factor of $HCl$ is 1, normality = molarity