British Sign Language Glossaries of Curriculum Terms

BSL Chemistry Glossary - Haber process - Definition

The Haber Process is a way of making Ammonia (NH₃) which is a very smelly gas.

The reason why it's used is that farmers across the world use a lot of fertiliser to help their crops grow.

Fertiliser has Nitrogen in it (N₂) but it's difficult to make fertiliser from the Nitrogen gas in the air, but we can use this process here on the screen to make Ammonia (NH₃) from N₂ mixed with H₂ which reacts to form a compound that is soluble in water that can then be used as a fertiliser to help make crops grow.

But, given the difficulty using the N₂ how can we make Ammonia?

First of all we collect Nitrogen from the air, then we take Hydrogen from steam by mixing it with Methane (the reaction released Hydrogen). The Hydrogen and Nitrogen are then mixed and compressed to 200 atmospheres (atm).

The next stage in the process is to add a catalyst to get them to react with one another to make Ammonia. The catalyst is Fe (Iron) and this is done at 450°C. The combined pressure of 200 atm and the very high temperature (450°C) helps speed up the reaction, this is needed because this reaction is reversible. The high temperature forces the reaction in one direction and stops it moving back the other way.

The next part of the process is to cool things down to room temperature where the Ammonia turns into a liquid which is then collected.

There will still be some Hydrogen and Nitrogen gas (because the reaction is reversible); this is collected and put back into the process and where it is again forced to react back in the other direction.