Question

Molarity of $H_{2}S{O}_4$ is $18$ M. Its density is $1.8g/c{m}^3$, hence molality is:

• A. $18$
• B. $100$
• C. $36$
• D. $500$

Answer 1

The correct option is D $500$

The molarity of $H_{2}S{O}_4$ is $18$ M.

Hence, $1$ L of $H_{2}S{O}_4$ corresponds to $18$ moles of $H_{2}S{O}_4$.

The density of $H_{2}S{O}_4$ is $1.8$ g/mL.

Thus, $1$ L of $H_{2}S{O}_4$ corresponds to $1800$ g or $1.8$ kg.

Out of this, $18\times 98=1764$ g or $1.764$ kg corresponds to $H_{2}S{O}_4$.

Hence, the mass of water is $1.8-1.764=0.036$ kg.

Hence, the molality of the solution is $\frac{18}{0.036}=500$ m.