Question

$36.5$% HCl has density equal to $1.20$ $gm{l}^{-1}$. The molarity (M) and molality (m), respectively, are :

• A. 15.7, 15.7
• B. 12, 12
• C. 15.7, 12
• D. 12, 15.7

Answer 1

The correct option is D 12, 15.7

$M=\frac{\text{percentage by weight}\times 10\times d}{M{w}_2}=\frac{36.5\times 10\times 1.2}{35.5}=12M$
$M=\frac{36.5\times 1000}{36.5(100-36.5)}=\frac{1000}{63.5}=15.7m$