Question

Nitric acid is manufactured by Ostwald process.

1. Give the source of ammonia used in the manufacture.
2. What is the ratio of ammonia and air are taken in this process.
3. Name the catalyst used in the process.
4. Name the oxidising agent used in this process.

Answer 1

Ostwald process:

• The Ostwald process is a process used for manufacturing Nitric acid.
• It converts ammonia to nitric acid and involves two steps,
• In step 1 ammonia is oxidized to form nitric acid and nitrogen dioxide and in the second step, nitrogen dioxide is absorbed in water which in turn forms nitric acid.

Part 1: Source of ammonia

• Ammonia is used as a source of Nitric oxide as it is produced on large scale by Haber's process.

$\underset{}{\underset{\mathrm{Nitrogen}}{{\mathrm{N}}_2\left(\mathrm{g}\right)}}+\underset{}{\underset{\mathrm{Hydrogen}}{3{\mathrm{H}}_2\left(\mathrm{g}\right)}}\stackrel{\mathrm{Fe},\mathrm{Mo}}{\rightleftharpoons }\underset{}{\underset{\mathrm{Ammonia}}{2{\mathrm{NH}}_3\left(\mathrm{g}\right)}}$

Part 2: Ratio of ammonia and air

The ratio of ammonia taken in the air is 1:10.

Part 3: Name the catalyst

Platinum is used as a catalyst in the manufacturing of nitric acid because in the production process part of platinum is lost as fine dust which is deposited on the internal reactor walls and cooling coils.

Part 4: Oxidizing agent

Oxygen is used as an oxidizing agent in the manufacture of Nitric acid as oxygen oxidizes the ammonia to nitric oxide and reduces itself to water.

$$\begin{gathered} \underset{}{\underset{\mathrm{Ammonia}}{4{\mathrm{NH}}_3\left(\mathrm{g}\right)}}+\underset{}{\underset{Oxygen}{5{\mathrm{O}}_2\left(\mathrm{g}\right)}}\rightleftharpoons \underset{}{\underset{\mathrm{Nitric}\mathrm{oxide}}{4\mathrm{NO}\left(\mathrm{g}\right)}}+\underset{}{\underset{\mathrm{Water}}{6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)}} \\ \underset{}{\underset{\mathrm{Nitric}\mathrm{oxide}}{2\mathrm{NO}\left(\mathrm{g}\right)}}+\underset{}{\underset{Oxygen}{{\mathrm{O}}_2\left(\mathrm{g}\right)}}\rightleftharpoons \underset{}{\underset{\mathrm{Nitrogen}\mathrm{dioxide}}{2{\mathrm{NO}}_2\left(\mathrm{g}\right)}} \\ \underset{}{\underset{\mathrm{Nitric}\mathrm{oxide}}{3{\mathrm{NO}}_2}}+\underset{}{\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}}}\to \underset{}{\underset{Nitricacid}{2{\mathrm{HNO}}_3}}+\underset{}{\underset{\mathrm{Nitric}\mathrm{oxide}}{\mathrm{NO}}} \end{gathered}$$