The Haber process makes ammonia for fertilisers

1. The Haber process manufactures ammonia, ${NH}_3$, on an industrial scale.
2. Ammonia is used to make nitrogen-based fertilisers, which raise crop yields.
3. Producing ammonia this way is vital for growing enough food for a rising population.

Raw materials: nitrogen from the air, hydrogen from natural gas

1. Nitrogen is obtained from the air, which is about 78% nitrogen.
2. Hydrogen is obtained from natural gas, which is mainly methane.
3. The two gases are purified before they enter the reactor.

The reaction conditions

1. The purified gases are passed over an iron catalyst.
2. The reactor runs at a temperature of about 450 degrees Celsius.
3. It also runs at a high pressure of about 200 atmospheres.
4. The reaction is reversible: $N_2+3H_2\rightleftharpoons 2{NH}_3$.

Separating and recycling the gases

1. The reaction never uses up all the nitrogen and hydrogen, so the mixture leaving the reactor contains all three gases.
2. The mixture is cooled so that the ammonia condenses into a liquid and is removed.
3. The unreacted nitrogen and hydrogen are recycled back into the reactor.
   1. Recycling means very little of the raw material is wasted.

What the ammonia is used for

1. Most of the ammonia is used to make nitrogen-based fertilisers, such as ammonium salts.
2. Ammonia is also used to manufacture nitric acid.
3. These products support farming, so the Haber process underpins the world's food supply.