The Haber process is a nitrogen fixation reaction which produces ammonia. The balanced chemical equation for the Haber process is:
N2 (g) + 3 H2 (g) ⇌ 2 NH3 (g)
A catalyst like Iron (Fe) is normally utilized. Pressure of around 20 MPa are often used and temperatures of 300-500 degrees Celsius. The gases are passed over many containers of catalyst, where they are cooled in between each container to ensure adequate yield. The over-all yield of the Haber process can be as high as 99%, but it is repeated often many times to achieve such a high yield.
The Haver process uses nitrogen, hydrogen, and an iron catalyst to produce ammonia. Generally speaking, it performs best under high atmospheric pressure and at reasonably high temperatures that produce ammonia in liquid form.