Question

$H_{2}S{O}_4$ is $98\%$ by weight of solution .Hence it is ?

• A. 1 molal
• B. 10 molal
• C. 50 molal
• D. 500 molal

Answer 1

Answer: (D)

500 molal

Let the weight of solution be $100g$

Then the weight of $H_{2}S{O}_4$ will be $98g$

$\therefore$ Number of moles of $98$% $H_{2}S{O}_4$

$=\frac{\text{Weight}}{\text{Molecular mass}}$

$=\frac{98}{98}=1$

Molality= $\frac{\text{No. of moles of solute}}{\text{Weight of solvent}}$ (Weight of $H_{2}O=100-98=2g$)

$=\frac{1}{2}$

$=\frac{1}{2}\times 1000=500$ molal solution (Converting into kg)