Question

How do we find the valency factor of oxalic acid and similar compounds?

Answer 1

Basicity of sulphuric acid is 2. Hence, equivalent weight of sulphuric acid (H2SO4) is (2X1 + 32 + 4X16)/2 = 98/2 = 49. Similarly, basicity of oxalic acid is 2. Hence, equivalent weight of oxalic acid (H2C2O4 ) is (2X1 + 2X12 + 4X16)/2 = 90/2=45.

Phosphorous based acids like phosphoric acid (H3PO4 ), phosphorous acid (H3PO3) and hypo-phosphorous acid (H3PO2) need special mention here to understand their basicity. The structures of three acids are shown here. From the structure, it appears that these compounds may furnish OH ions, but bond strengths between phosphorous and oxygen (P-O) and phosphorous and hydrogen (P-H) are stronger than between oxygen and hydrogen (O-H) in –OH group. As such, these molecules release hydrogen ions from –OH group and behave as acid. Clearly, basicities of phosphoric acid (H3PO4), phosphorous acid (H3PO3) and hypo-phosphorous acid (H3PO2) are 3, 2 and 1 respectively

Answer 2

Hello buddy,

● Valence factor -
- Valence factor is the change in oxidation state of the molecule in a reaction.
- For acids, valence factor is no of H+ ions released by acid in reaction.
- For bases, valence factor is no of OH- ions released by base in reaction.
- Oxalic acid gives 2 H+ ions in solution, hence its valence factor is 2.
(COOH)2 --> (COO-)2 + 2H+


Thanks for asking...