Question

Upon heating a litre of $\left(N/2\right)HCl$ solution, $2.675g$ of hydrogen chlorine is lost and the volume of the solution shrinks to $750mL$. What is the normality of the resultant solution?

• A. $0.569N$
• B. $0.5N$
• C. $0.42N$
• D. $1.707N$

Answer 1

The correct option is A $0.569N$

Normality and molarity of $HCl$ solution is equal.

The solution is $12.178$ $N$ for density of $1.2$ $g/mL$, concentration of $37\%$ $W/W$ and formulae weight of $30.46$ $g/mL$ for $1$ $L$ of $HCl$.

For $37\%$ $W/W$ solution,

$1000$ $g$ of water contain $370$ $g$ of $HCl$

$\left(N/2\right)HCl$ is made by $41.059$ $mL$ of original solution i.e.,

$1000$ $mL$ of $0.5$ $N$ $HCl$ has $=\frac{37}{100}\times 41.059=15.192$ $g$ of $HCl$

On heating, $2.675$ $g$ of $HCl$ is evaporated.

Remain weight $=15.192-2.675=12.517$ $g$

And volume is $570$ $mL$

$Molarity=\frac{Molesofsolute}{Volumeofsolvent}=\frac{\left(\frac{12.517}{36.5}\right)}{570}=0.569$ $N$

Since,

Normality $=$ Molarity of $HCl$

$\therefore$ Solution is $0.569$ $N$