Question

Equivalent weight of hydrated oxalic acid is:

A. 44

B. 45

               C. 63

D. 126

Answer 1

Hint: Equivalent weight is the mass of one equivalent of any specific substance that can combine with one gram of hydrogen or displace a fixed quantity of another substance. Equivalent mass is calculated by the formula $\text{Gram atomic weight }\!\!\div\!\!\text{ Valency}\text{.}$

Complete step by step solution:
${{\text{C}}_{\text{2}}}{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{4}}}\cdot \text{2}{{\text{H}}_{\text{2}}}\text{O}\text{.}$Oxalic acid is mostly present in crystalline hydrated. Oxalic acid is a white crystalline solid that forms a colorless solution in water. It is mainly used as a reducing agent. It occurs naturally in many foods, but its excessive intake will be dangerous for the health.
Oxalic acid is also used by some beekeepers as a miticide against the parasitic varroa mite.
Writing the mass of C(carbon) which is 12, mass of Hydrogen(1),mass of oxygen(16), so the total mass of Hydrated oxalic acid comes out to 126g.
As we know that equivalent mass of any substance is :$\text{Gram atomic weight}\div \text{Valency}$
Valence is defined as the number of electrons needed to fill the outermost shell or sometimes it is also defined as the number of electrons or ions an atom or acid and base can donate to attain the stable electronic configuration. For example in case of acid and base we take valence as the no of H+ or OH- ions released.
In case of oxalic acid ,the acid releases 2${{\text{H}}^{+}}$ ions, hence valence is 2.
So the equivalent weight of oxalic acid will be $126\div 2$ =63 g/eq mol.
Therefore, the option C will be correct.

Note: Hydrated means which always have water molecules. Sometimes students in hurry forget to note that it is hydrated given, instead of taking the weight of a hydrated molecule they just take the weight of oxalic acid.