Question

Calculate the strength of $10$ volume solution of hydrogen peroxide.
A. $3%$
B. $4%$
C. $1%$
D. $2%$

Answer 1

Hint: Volume strength of hydrogen peroxide is the volume of oxygen released on decomposition of one volume of hydrogen peroxide at standard temperature and pressure (STP). So, $10$ volume hydrogen peroxide on reduction will release ten times the volume of the sample at STP.

Complete step by step solution:
Given that,
We have to find the strength of a $10$ volume solution of hydrogen peroxide.
So, for finding the volume strength we have to write a balanced equation of hydrogen peroxide i.e. ${{H}_{2}}{{O}_{2}}$ decomposition to form water and oxygen.
So, here is the balanced chemical reaction of ${{H}_{2}}{{O}_{2}}$ decomposition to form water and oxygen:
$2{{H}_{2}}{{O}_{2}}\to 2{{H}_{2}}O+{{O}_{2}}$
$2\times 34g=68g$ $22.4 l at STP$
As we can see that, in ${{H}_{2}}{{O}_{2}}$oxidation state of oxygen is $-1$, because when we apply the rule that sum of oxidation number of all the atoms in a neutral compound is zero and here oxidation state of hydrogen atom is $+1$, so the oxidation state of oxygen atom will be $-1$.
Similarly, in ${{H}_{2}}O$oxidation state of oxygen will be $+2$, and in ${{O}_{2}}$oxidation state is $0$.
So, from the balanced reaction of ${{H}_{2}}{{O}_{2}}$, we can see that two moles of ${{H}_{2}}{{O}_{2}}$is giving one mole of ${{O}_{2}}$.
As we know that one mole of any gas at STP has volume $22.4$ litres.
Therefore, one mole of ${{H}_{2}}{{O}_{2}}$ at STP will give $22.4$ litres of oxygen.
As per the given question,
$10$ volume solution of ${{H}_{2}}{{O}_{2}}$means that one litre of this solution will give $10$ litres of oxygen at STP.
On the basis of the above equation, $22.4$ litres of oxygen are produced from $68g$${{H}_{2}}{{O}_{2}}$ at STP.
So, $10$ litres of Oxygen at STP is produced from $\dfrac{68\times 10}{22.4}=30.36\approx 30g$${{H}_{2}}{{O}_{2}}$.
Therefore, strength of ${{H}_{2}}{{O}_{2}}$in $10$ volume ${{H}_{2}}{{O}_{2}}$ solution is $30g$ per litre i.e. $3%$${{H}_{2}}{{O}_{2}}$ solution.

Hence, the correct option is A.

Note: Volume strength of hydrogen peroxide is the concentration of ${{H}_{2}}{{O}_{2}}$ in terms of volumes of oxygen gas based on its decomposition to form water and oxygen. So here, $10$ volume solution of ${{H}_{2}}{{O}_{2}}$ means that one litre of this solution will give $10$ litres of oxygen at STP. Possibly, you may make mistakes in balancing the decomposition reaction.