Question

calculate the equivalent weight of H3PO4 and Ca(OH)2 on the basis of given reaction.

H3PO4+NaOH gives NaH2PO4+H2O

Ca(OH)2 +HCl gives Ca(OH)Cl+H2O
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Answer 1

Answer:

An equivalent weight of a solution is defined as the molecular weight of the solute divided by the valence of the solute. Equivalent weight is used for predicting the mass of a substance that reacts with one atom of hydrogen in an acid-base analysis like in titration.

The given reaction is:

Ca(OH)2 + H3PO4 → CaHPO4 + 2H2O

In the reaction,

H3PO4 → HPO42- + 2H+

2 hydrogen ions are left from the orthophosphoric acid.

Therefore, the valency factor = 2

Equivalentweight=molecularweight2

Molecular weight calculation.

Number of H are 3

3 × 1 = 3

Number of P is 1

1 × 31 = 31

Number of O are 4

4 × 16 = 64

Molecular weight = 3 + 31 + 64

Molecular weight = 98

Therefore, the equivalent weight = (98/2) = 49

Equivalent weight of H3PO4 is 49.