How is fertilizer made?

We started off today's session by examining pea shoots' roots nodules. Magnus recalled the role of the nitrogen-fixing bacteria that call them home! Then we used our knowledge of the nitrogen cycle to determine that fertilizer should contain water-soluble forms of ammonium and nitrate, so as to make nitrogen readily available to plants.

We puzzled over how to create these chemicals industrially, ultimately learning that nitrogen is extracted from the air using a temperature-dependent process (fractional distillation), and that hydrogen is extracted from methane using heat. We balanced an equation to determine the quantities of nitrogen and hydrogen gas necessary to produce ammonia, thinking carefully about the conditions necessary to prevent nitrogen from reverting to a gas. Once we realized the importance of pressure to this part of the process, we balanced four more equations to determine how ammonia is used to make nitrous oxide (laughing gas), which is used to make nitrogen dioxide (a major component of smog), which, in turn, is used to make nitric acid.

We wrapped up our learning with a video showing each step in action at a fertilizer plant, including the final one: the synthesis of ammonia gas and nitric acid to form ammonium nitrate fertilizer. We also considered the roles of oxygen, water, and iron and platinum catalysts, remembering that enzymes are catalysts, too. Jasper ended our session with an innovative idea: using the smog emitted by cars to increase the sustainability of fertilizer production!

By GCSE - Ammonia and Fertilisers.
Video highlights a fertilizer plant, including the final one: the synthesis of ammonia gas and nitric acid to form ammonium nitrate fertilizer.