Question

$2H_2{O}_2\left(l\right)\to 2H_{2}O\left(l\right)+O_2\left(g\right)$

$100$ mL of $xM$ $H_2{O}_2$ gives $3$ L of $O_2$ gas under the condition when $1$ mol occupies $24$ L. The value of $x$ is:

• A. $2.5$
• B. $1.0$
• C. $0.5$
• D. $0.25$

Answer 1

Answer: (A)

$2.5$

The number of moles of $H_2{O}_2$ present in $100$ mL of $xM$ solution is $0.1x$ moles.
$2$ moles of $H_2{O}_2$ on decomposition will give $1$ mole of oxygen which will occupy a volume of $24$ L.
The number of moles corresponding to $3$ L of oxygen is $\frac{1}{8}$ mol.
This is also equal to $\frac{1}{4}$ mol $H_2{O}_2$.
Thus, $0.1x=\frac{1}{4}$
or $x=2.5$

Hence, the value of $x$ is $2.5$.