Question

The steps for the manufacture of nitric acid by Ostwald process are given. Arrange them in sequence.
(a) Recirculation of nitric oxide
(b) Addition of $H_{2}O$ to nitrogen dioxide
(c) Oxidation of nitric oxide.
(d) Catalytic oxidation of ammonia

• A. d c b a
• B. d c a b
• C. c d b a
• D. c d a b

Answer 1

The correct option is A d c b a

In the first step of Ostwald process, ammonia is oxidised to form nitric oxide.

$4N{H}_3+5O_2\leftrightarrow 4NO+6H_{2}O$

In the second step, nitric oxide is oxidised to form nitrogen dioxide.

$2NO+O_2\leftrightarrow 2N{O}_2$

Then, nitrogen dioxide is mixed with water in an absorption tower to get nitric acid.

$3N{O}_2+H_{2}O\to 2HN{O}_3+NO$

Lastly, nitrogen dioxide is recirculated in the absorption tower to ensure that more and more of it is absorbed with water to increase the concentration of nitric acid. The vapours of nitric acid are then passed over concentrated sulphuric acid that absorbs water from it to increase its concentration further.