Question

What is the weight by volume percentage of \[3N\text{ }{{H}_{2}}S{{O}_{4}}\] solution?
A.$5%$
B.$10%$
C.$14.7%$
D.$20%$

Answer 1

Hint: We know that the concentration of a solution can be measured with the help of normality. Normality is the ratio of a number of grams equivalent by volume of solution in litre. It can measure the number of ions in the precipitation reaction.

Complete answer:
In the mole concept we have studied about the molarity and we have studied that molar concentration of substance is also known as molarity. It is defined as the ratio of moles of substance to volume of solution in litre. Mole is defined as weight in grams divided by the molecular weight of the substance. So we will find out the molarity by the formula; M = Number of moles of solute /volume of the solution in litre
Normality is used for the acid and bases mostly. The normality is also related to the molarity and normality is equal to the product of n and molarity where n is equal to the number of hydrogen ions in the acid or no. of hydroxyl ions in the base or n-factor. Once the number of moles is determined we calculate molarity of sulphuric acid easily with the help of molarity formula.
\[Normality\text{ }=\text{ }\dfrac{Weight}{Equivalent\text{ }Weight}\times \dfrac{1}{V(L)}\]
Substituting the given values;
\[3N\text{ }=\text{ }\dfrac{x}{\left( \dfrac{98}{2} \right)}\times \dfrac{1000}{V(mL)}\] Here it is multiplied by $1000$ since we have done from L to mL.
On further solving we get;
\[\dfrac{x}{V}\times 1000=\dfrac{3\times 98}{2}\]
From the above equation, we get;
\[\Rightarrow \dfrac{x}{V}\times 100=\dfrac{147}{10}\]
Therefore, \[\Rightarrow \dfrac{w}{V}%=14.7%\]
Therefore, the correct answer is option C.

Note:
Remember that in mole problems we should always remember some important relation .Here in this problem we have used some relations to solve the problem as we have found the mass with the help of given density and then put the value of mass in the formula to find the number of moles.