GCSE Chemistry: NPK fertilisers

what do NPK fertilisers contain?

nitrogen, phosphorus, potassium

how do we get the nitrogen for fertilisers?

from ammonium nitrate

how do we get ammonium nitrate?

ammonia from the Haber process is used to make nitric acid, the nitric acid is reacted with more ammonia to make ammonium nitrate

how do we get the potassium?

by mining the salts potassium chloride and potassium sulfate

how do we get the phosphate?

by mining phosphate rock from the ground then chemically processing it

what is produced when you add nitric acid to phosphate rock?

phosphoric acid and calcium nitrate

what do we then do to phosphoric acid?

neutralise it with ammonia to make ammonium phosphate which is used in NPK fertilisers

what is produced when you add sulfuric acid to phosphate rock?

single superphosphate-a mixture of calcium phosphate and calcium sulfate used in NPK fertilisers

what is produced when you add phosphoric acid to phosphate rock?

triple superphosphate (calcium phosphate) used in NPK fertilisers