This short lesson from eGogy explains the Haber process, the industrial way to make ammonia. Nitrogen and hydrogen react under high pressure, about 150 to 300 atmospheres, over an iron catalyst at 450 to 500 °C. The hydrogen comes from methane and steam, and the nitrogen comes from the air. The ammonia is cooled until it turns liquid, and the gases that did not react are used again.
I use it to explain one step of the chemical plant theory on my page about the Red Pyramid.
Video by eGogy. Watch on YouTube.