Chapter 21, Problem 51PS

(a)

Interpretation Introduction

Interpretation: The oxidation number of phosphorous atom in the phosphorous acid is to be stated.

Concept introduction:

Oxidation number is also called oxidation state. The total number of electrons that an atom gain or loss to form a chemical bond with another atom is known as its oxidation state.

Oxoacids are the acids containing oxygen atoms. Phosphorous is one element that forms a number of oxoacids. The phosphorous acid is an oxoacid of phosphorous atom.

(b)

Interpretation Introduction

Interpretation: To draw the structure of diphosphorous acid, ${\text{H}}_{\text{4}}{\text{P}}_{\text{2}}{\text{O}}_{\text{5}}$ and maximum number of ionisable protons in diphosphorous acid is to be stated.

Concept introduction: In oxoacids of phosphorous, the phosphorous is tetrahedrally surrounded by other atoms. There are atleast one $\text{P=O}$ and one $\text{P}-\text{OH}$ bond in these acids. $\text{P}-\text{P}$ and $\text{P}-\text{H}$ bonds are also present besides the $\text{P=O}$ bonds and $\text{P}-\text{OH}$ bonds in oxoacids of phosphorous.