GCSE SCIENCE CHEMISTRY HIGH SCHOOL - Manufacture of Nitric Acid from Ammonia - Reactions

How is Nitric Acid Made?

Nitric acid is made from the reaction of ammonia with oxygen.

The first stage produces nitrogen monoxide.
(The same gas is formed as a pollutant in Petrol Engines).

A hot platinum catalyst is used (about 850 °C).
The reaction is highly exothermic and the heat given out by
the reaction is sufficient to keep the reaction going.

ammonia + oxygen nitrogen monoxide + water.
4NH₃_(g) + 5O_2(g) 4NO_(g) + 6H₂O_(g)

The second stage involves the reaction of
nitrogen monoxide with more oxygen.

nitrogen monoxide + oxygen nitrogen dioxide.
2NO_(g) + O_2(g) 2NO₂_(g)

Finally, nitrogen dioxide reacts with water and more oxygen.

nitrogen dioxide + oxygen + water nitric acid.
4NO₂_(g) + O_2(g) + 2H₂O_(l) 4HNO₃_(aq)

The overall reaction is

ammonia + oxygen nitric acid + water.
4NH₃_(g) + 8O_2(g) 4HNO₃_(aq) + 4H₂O_(l)

This is the oxidation of ammonia to produce nitric acid.

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