Nitrogen and hydrogen are two elements used to make ammonia (NH3), a poisonous, colourless gas which has a pungent odour. The method used in industry to make ammonia is called the Haber process. It was invented by a German chemist, Fritz Haber in 1909. The process operates at a high temperature ( approx 450 degree celcius) and pressure ( up to 1000 atmospheres), with iron as a catalyst.Nitrogen+ Hydrogen== Ammonia.The Haber process is a reversible reaction*. The gases are cooled and the ammonia is seperated. Only about 15% of the mixture is converted to ammonia. The uncreated substances are recycled. Ammonia forms an alkaline* solution in water called ammonium hydroxide, or aqueous ammonia.(also used as a degreasing agent in household cleaners.)