Write the balanced chemical equation with condition involved in the manufacture of nitric acid by Ostwal's process .

Explanation

MANUFACTURE (ostwald.s process). This method was established by Withelm Ostwald.s (1902).In this method, `HNO_3` is manufactured by oxidation of ammonia. The main steps in this process are: (i) Catalytic oxidation of ammonia. A gaseous mixture containing pure and dry air in the ratio of 1:10 by volume,is passed through a steel shell or aluminium converter having platinum gauze heated electrically to about 1100 K. Ammonia is oxidised to nitric oxide and the reaction is exothermic `4H_3+5O_2 underset("500k, bar")overset("PURh gaugo catalyst")to 4NO+6H_2O` To start with, the catalyst is heated electrically. As the reaction proceeds, enough heat is proceduced which maintains the required temperature and external heating is stopped. (ii) Oxidation of nitric oxide. The nitric oxide obtained above is cooled and passed through a spacious chamber called oxidising chamber. The nitric oxide is oxidised to nitrogen dioxide. 2NO(g) + `O_2(g)hArr2NO_2(g)` (iii) Absorption tower. The gases are then introduced in the absorption tower which is packed with acid proof stones. Water sprayed from the top dissolves nitrogen dioxide in the presence of oxygen to give about 60% nitric acid `3NO_2+H_2O(1)to2HNO_3(aq)+NO(g) 4NO_2(g)+2H_2O(1)+O_2(g)to 4HNO_3(aq)` The acid flows down and is withdrawn from the tower with the help of a tap. Futher concentration of nitric acid can be done to 98% acide by dehydration with. concentrated sulphuric acid.