Question

${P_4}{O_6}$ reacts with water to give:
(A) ${H_3}P{O_3}$
(B) ${H_2}{P_2}{O_7}$
(C) $HP{O_3}$
(D) ${H_3}P{O_4}$

Answer 1

Phosphorus trioxide reacts with hydrogen chloride to give phosphorous trichloride and phosphoric acid. In the given question we need to know the product formed when the ${P_4}{O_6}$ reacts with water.

Complete step by step answer:
${P_4}{O_6}$ reacts with water to give phosphoric acid.
The chemical name of ${P_4}{O_6}$ is Phosphorus trioxide.
The structure is:

It is formed by burning phosphorus in the limited supply of oxygen. The reaction is as follows:
${P_4} + 3{O_2} \to {P_4}{O_6}$
This product reacts with water and forms phosphorus acid. The chemical formula of phosphoric acid is ${H_3}P{O_3}$ The structure is:

The reaction occurs as follows: ${P_4}{O_6} + 6{H_2}O \to 4{H_3}P{O_3}$
Hence, option A. ${H_3}P{O_3}$ is the correct answer to the given question.

Additional information:

${H_3}P{O_3}$ exists in tautomeric form because they are readily convertible and the former is called phosphonic acid whereas the latter is called phosphoric acid.

Note:
Uses of ${H_3}P{O_3}$ :
For the production of basic lead phosphite. It is used as a stabilizer in Polyvinyl chloride and other polymers containing chlorine.
As a reducing agent: it is a strong reducing agent which is also used in production of synthetic fibers and pesticides.
As a ligand: with the metals of ${d^6}$ configuration, it acts as a ligand by forming a co-ordinate bond with those metals.