Question

Write the chemical equation for the preparation of phosphoric $\left( {{H_3}P{O_4}} \right)$acid from ortho phosphoric acid$\left( {{H_3}P{O_3}} \right)$ .

Answer 1

Hint:Phosphorus forms a variety of compounds with oxygen,each of which has different characteristics.Preparation of phosphoric acid from orthophosphorus acid is done by heating in the presence of oxygen or when heated in temperature above 1800 C.

Complete answer:
Phosphoric acid, also named as orthophosphoric acid, $\left( {{H_3}P{O_4}} \right)$ the most imperative oxygen acid of phosphorus, used to prepare phosphate salts for fertilizers. It is also used in dental cements, in the preparation of albumin derivatives, and in the sugar and textile industry .
Phosphorus acid is the compound labelled by formula $\left( {{H_3}P{O_3}} \right)$ used in the creation of raw materials of phosphorus acid, synthetic fibers and organophosphorus pesticides etc .
The chemical equation for the preparation of phosphoric $\left( {{H_3}P{O_4}} \right)$acid from orthophosphorus $\left( {{H_3}P{O_3}} \right)$ acid .
${H_3}P{O_3} + \frac{1}{2}{O_2} \to {H_3}P{O_4}$
In the above reaction we can see that preparation of phosphoric acid from orthophosphorus is done by heating in the presence of oxygen .

Note:we can also obtain phosphoric acid by adding sulphuric acid to the phosphate of baryta forming an insoluble salt which precipitates while the phosphoric acid remains in solution . About 90 % of phosphoric acid is produced for preparation of fertilizer.