Question

Concentrated hydrochloric acid is $36.5$% by weight. What is the molality of the solution?

• A. $1.575molal$
• B. $15.75molal$
• C. $157.5molal$
• D. $1575molal$

Answer 1

The correct option is B $15.75molal$

Let us assume that there is $100gm$ of solution

Mass of $HCl=36.5gm$

Mass of $H_{2}O=63.5gm$

Moles of $HCl=\frac{36.5}{36.5}=1mole$

Molality $=\frac{moles}{massofsolvent\left(kg\right)}=\frac{1}{63.5/1000}=\frac{1000}{63.5}=15.75molal$