Question

For $ 2.95\text{ }M\text{ }{{H}_{2}}{{O}_{2}} $ solution, what will be the grade (strength by volume) and percentage strength?
(A) $ 28.10 $
(B) $ 35.12 $
(C) $ 33.10 $
(D) $ 36.12 $

Answer 1

Hint :We know that the amount of solute or the concentration of solute present in the total solution is known as the strength. The term Volume strength indicates the volume of oxygen produced by one liter of hydrogen peroxide. We know that volume strength is the number of volumes of oxygen liberated by one litre of hydrogen peroxide.

Complete Step By Step Answer:
Volume strength is nothing but the number of volumes of oxygen liberated by one liter of hydrogen peroxide. This statement seems somewhat typical so we will try to understand it by its derivation. We have to make oxygen from hydrogen peroxide. $ 2{{H}_{2}}{{O}_{2}}\to 2{{H}_{2}}O+O2 $ two moles of hydrogen peroxide produces one mole of oxygen gas.
Since, volume strength of $ {{H}_{2}}{{O}_{2}}=11.2\times Molarity $
and here molarity is $ 2.95M $ by substituting in above formula we get;
Volume Strength of $ {{H}_{2}}{{O}_{2}}=11.2\times 2.95=33V $
Also since $ 10V $ corresponds to $ 3% $ of strength;
 $ 100% $ Strength $ =333V $
Thus, Percentage Strength of $ 33V=\dfrac{33}{333}\times 100=10% $
Therefore, the correct answer is option C.

Additional Information:
Hydrogen peroxide decomposes very easily. Hydrogen peroxide easily decomposes to two components i.e. water and oxygen. Molarity and molality should not be confused; both are different; molarity is temperature dependent while molality is temperature independent. Unit conversions in such questions should be done carefully.

Note :
Remember that the hydrogen peroxide decomposes vigorously. It decomposes itself into two components: water and oxygen. If it is decomposed in an environment it will form some other compounds made up of hydrogen and oxygen but in vacuum only the water and oxygen molecules are formed.