Question

If $100mL$ of the acid is neutralised by $100mL$ of $4MNaOH$, the purity of concentrated $HCl$ (sp. gravity $=1.2)$ is:

• A. $12$%
• B. $98$%
• C. $73$%
• D. $43$%

Answer 1

The correct option is A $12$%

No of equivalent of acid $=$ No of equivalent of base.

$100\times m_1=100\times 4$

$m_1=4m$

$4$mole of $HCL$ in $1$liter of water..........$\left(1\right)$

$\frac{\rho HCl}{\rho H_{2}O}=k$

density of $HCl=1200gm/l$...........$\left(2\right)$

purity of $HCl\Rightarrow 1200gmin1liter$

purity of $HCl$ in gram in $1$ liter $\Rightarrow 1200gm$

purity of $HCl\Rightarrow$ $\frac{4\times 36.5}{1200}\times 100\Rightarrow \sim 12\%$

hence, purity of $HCl$ is $\sim 12\%$

so option $A$ is correct.