Question

Calculate the molecular weight of a dibasic acid.0.56gm of which is required 250ml of N/20 sodium hydroxide solution for neutralization.​

Answer 1

Answer: The molecular weight of the dibasic acid is 89.6 g/mol

Explanation:

Normality is defined as the amount of solute expressed in the number of gram equivalents present per liter of solution. The units of normality are eq/L. The formula used to calculate normality:

$\text{Normality}=\frac{\text{Given mass of solute}\times 1000}{\text{Equivalent mass of solute}\times \text{Volume of solution (mL)}}$      ....(1)

We are given:

Normality of solution = $\frac{1}{20}=0.05N$

Given mass of solute = 0.56 g

Volume of solution = 250 mL

Putting values in equation 1, we get:

$0.05=\frac{0.56\times 1000}{\text{Equivalent mass of solute}\times 250}\\\\\text{Equivalent mass of solute}=\frac{0.56\times 1000}{0.05\times 250}=44.8g/eq$

Equivalent weight of an acid is calculated by using the equation:

$\text{Equivalent weight}=\frac{\text{Molar mass}}{\text{Basicity}}$   .....(2)

Equivalent weight of acid = 44.8 g/eq

Basicity of an acid = 2 eq/mol

Putting values in equation 2, we get:

$44.8g/eq=\frac{\text{Molar mass}}{2eq/mol}\\\\\text{Molar mass}=(44.8g/eq\times 2eq/mol)=89.6g/mol$

Hence, the molecular weight of the dibasic acid is 89.6 g/mol