Atmospheric nitrogen, with the aid of an iron catalyst, reacts with hydrogen to produce ammonia. That reaction produces lots of ammonia – worldwide production is 160 million tons every year.

can react to form ammonium chloride again. This slideshow shows a reversible reaction involving white anhydrous copper(II) sulfate and blue hydrated copper(II) sulfate. The equation for this is ...

ammonium nitrate and ammonium sulfate – can be identified by heating a solution of the ions with sodium hydroxide. This reaction produces ammonia gas, as shown in the ionic equation below: ...