Question

Give balanced equations and principle involved in the manufacture of nitric acid $\left(HN{O}_3\right)$ by Ostwald's process.

Answer 1

Ammonia is oxidized by atmospheric oxygen using catalyst. $4N{H}_3\left(g\right)+5O_2\left(g\right)\underset{500K,9bar}{\overset{Pt/Rhgaugecatalyst}{\to }}4NO\left(g\right)+6H_{2}O\left(g\right)$
Nitric oxide reacts with oxygen to form nitrogen dioxide
$2NO\left(g\right)+O_2\left(g\right)\rightleftharpoons 2N{O}_2\left(g\right)$
Nitrogen dioxide dissolves in water to form nitric acid.
$3N{O}_2\left(g\right)+H_{2}O\left(g\right)\to 2HN{O}_3\left(l\right)+NO\left(g\right)$
NO formed as byproduct is reused and aqueous $HN{O}_3$ is concentrated by distillation up-to 68% by mass. It is then dehydrated with water to form 98% by mass.