Question

The equivalent weight of phosphoric acid (H₃PO₄) in the reaction : 

NaOH + H₃PO₄ → NaH₂PO₄+ H₂O is

(a) 25

(b) 49

(c) 59

(d) 98

Answer 1

Option (D) is correct
NaOH is monoacidic base. So its molar mass is same as equivalent mass.
In this reaction 1g equivalent NaOH reacts with one mole H3PO4.

So molar mass of the acid is its equivalent mass.

Hence it will be =3×1+31+4×16=98

Answer 2

Correct option  (d) 98

Explanation:

The given reaction is :

NaOH + H₃PO₄ →  NaH₂PO₄ + H₂O

Molecular mass of H₃PO₄ is 98. As there is only one electron change involved therefore,

Equivalent weight of H₃PO₄ in this reaction is = 98/1 = 98