Question

Calculate the equivalent mass of sulphuric acid.

Answer 1

To solve this question, you need to know how to calculate the n-factor and molar mass of sulphuric acid $\left( {{H}_{2}}S{{O}_{4}} \right)$. Molar mass is the sum of atomic masses of the elements present in the molecule and you must take into account the number of atoms of each element.

Complete answer:
Let’s first understand what equivalent mass and n-factor is. Equivalent mass is the number of grams of any element that can combine with $1g$of hydrogen or $8g$ of oxygen or $35.5g$ of chlorine. The definition is not that important but you must know this. Unit of equivalent mass is g/equivalent. Mathematically, Equivalent mass is defined as:
$E=\dfrac{M}{n-factor}$
Where, E is the Equivalent mass and M is the molar mass.
We know how to calculate the molar mass but to know the equivalent mass we also need to know the n-factor which is defined for an acid as the number of ${{H}^{\oplus }}$ ions produced by one molecule of the acid or it is the number of neutralizable hydrogens per molecule of the acid. Infact, n-factor is the basicity of the acid.
Molar mass of ${{H}_{2}}S{{O}_{4}}$ is $2\left( 1 \right)+32+4\left( 16 \right)=98g/mol$
n-factor of ${{H}_{2}}S{{O}_{4}}$ is 2 as two hydrogen ions are being produced by sulphuric acid.
${{H}_{2}}S{{O}_{4}}\to 2{{H}^{\oplus }}+S{{O}_{4}}^{2-}$
Therefore, equivalent mass of ${{H}_{2}}S{{O}_{4}}$ is
$\dfrac{98}{2}=49g/equivalent$

Note:
In this question, we defined the n-factor of the acid. So for a base it is defined as the acidity of the base. For a salt, n-factor is the total positive charge of cations or total negative charge of anions in the formula of a salt.
For example, the n-factor of $BaC{{l}_{2}}$ is $2$.