The Haber process
Making ammonia
Ammonia is an important industrial product used to make fertiliserA nutrient added to the soil to increase the soil fertility., explosives and dyes. It is manufactured using the Haber processThe industrial chemical process that makes ammonia by reacting nitrogen and hydrogen together.. This involves a reversible reactionA chemical reaction which can go both ways. between nitrogen and hydrogen:
N2(g) + 3H2(g) 鈬 2NH3(g)
The reaction can reach a dynamic equilibriumIn chemical reactions, a situation where the forward and backward reactions happen at the same rate, and the concentrations of the substances stay the same..
In the Haber process:
- nitrogen (extracted from the air) and hydrogen (obtained from natural gasA naturally occurring hydrocarbon gas mixture.) are pumped through pipes
- a compressor increases the gas pressureForce exerted over an area. The greater the pressure, the greater the force exerted over the same area. to 200 atmosphereA unit of pressure.
- the pressurised gases are heated to 450掳C and passed through a reaction chamber containing an iron catalystA substance that changes the rate of a chemical reaction without being changed by the reaction itself. to speed up the reaction
- the reaction mixture is cooled so that ammonia liquefyTo turn from a gas to a liquid, usually by cooling or by being put under pressure. and can be removed
- unreacted nitrogen and hydrogen are recycledUsed materials that have been reprocessed to make new materials.
The conditions are chosen to ensure the process of making ammonia is as profitable as possible.
Question
Explain why iron is used in the Haber process.
Iron is a catalyst for the reaction. It increases the rate of the reaction without being used up in the reaction.
Question
State the reaction conditions used in the Haber process.
A pressure of 200 atmospheres.
A temperature of 450掳C.
An iron catalyst.