Question

The normality if 10 lit. volume hydrogen peroxide is:
[A] 0.176
[B] 3.52
[C] 1.78
[D] 0.88
[E] 17.8

Answer 1

Hint: To solve this, remember the definition of normality. Normality is the gram equivalent weight of solute per litres of solvent. Find out the gram equivalent by dividing its molecular weight by its valency factor.

Complete answer:
Before answering this, let us discuss what normality is.
Normality is a term that we use to define the concentration of a solution. It is the gram equivalent weight or number of equivalents per litre of solvent.
We can write it as- Normality = $\dfrac{gram\text{ equivalent of solute}}{Volume\text{ of solvent (L)}}$
We can find out the gram equivalent weight by dividing molar mass of the solute by its valency factor.
We know that hydrogen peroxide is ${{H}_{2}}{{O}_{2}}$ .
Therefore, its molecular weight will be - $\left( 2\times 1 \right)+\left( 2\times 16 \right)$ = 34 g/mol.
Also, hydrogen peroxide has two replaceable hydrogen atoms so it is dibasic. Therefore, its valency factor will be 2.
Therefore, we can write that, gram equivalent = $\dfrac{34\text{ }}{2}$ = 17 g
Now, the volume is given to us as 10L. Therefore, putting these values in the normality equation we can write that-
     $Normality=\dfrac{gram\text{ equivalent of solute}}{Volume\text{ of solvent (L)}}=\dfrac{17}{10}=1.7$
We can see that our calculated value is closest to 1.78.

Therefore, the correct answer is option [C] 1.78.

Note:
We should not be confused between normality, molarity and molality of a solution even though we use them for the same purpose i.e. to define the concentration of the solution. Molarity is the number of moles of solute per litre of solvent. Molality of a solution is the number of moles of solute per kilogram of solvent and we’ve already discussed normality above, which is the gram equivalent of solute per litre of the solvent.