resources - NPK fertilisers

Question 1

what are fertilisers important for + why?

Answer 1

critical for modern farming as they replace the elements which have been taken up by plants

Question 2

what elements are in NPK fertilisers? why these elements?

Answer 2

nitrogen, phosphorous and potassium.
they improve agricultural productivity. help plants to grow larger + more rapidly

Question 3

how are NPK fertilisers produced?

Answer 3

in large industrial facilities. a variety of different raw materials are processed together to produce the exact fertilisers required

Question 4

what are the formaultions in NPK fertilisers?

Answer 4

• the formulations are different salts
• these salts contain the elements in the percentages needed by the plants

Question 5

how are the compounds in NPK fertilisers produced?
nitrogen?

Answer 5

• ammonium nitrate (NH4NO3) is made by using ammonia produced by Haber process. use ammonia to produce nitric acid. then react nitric acid with more ammonia

Question 6

how are the compounds in NPK fertilisers produced?
potassium?

Answer 6

• the potassium comes from the salts potassium chloride or potassium sulfate. both compounds mined from the ground. can be used directly without further processing

Question 7

how are the compounds in NPK fertilisers produced?
phosphorous? with nitric acid? sulfuric acid? phosphoric acid?

Answer 7

• phosphate rock mined from ground and then chemically processed before being used in fertilisers
• treat phosphate rock with nitric acid produces phosphoric acid and calcium nitrate. the phosphoric acid contains phosphorous but we can’t add this directly to plants so neutralise it with ammonia. this produces ammonia phosphate which is used in NPK fertilisers
• treat phosphate rock with sulfuric acid, make a mixture of calcium phosphate and calcium sulfate. this is called single superphosphate.
• treat with phosphoric acid we make triple superphosphate

Question 8

how are the compounds in NPK fertilisers produced?
ammonium nitrate?

Answer 8

• produced by reacting ammonia with nitric acid. neutralisation reaction

Question 9

compare industrial production fertilisers with their production in a lab

Answer 9

-in the industry, ammonium is used as a gas and nitric acid is concentrated. this is much more dangerous as the reaction is very exothermic. heat produced has to be safely removed. this is then used in later stages. where as in school lab dilute solutions of ammonia and nitric acid that makes them safe to work with
- in the lab they produce crystals using a water bath and a bunsen burner. requires a lot of heat energy. in the industry some of the energy for evaporation is provided by the exothermic reaction earlier
- in a lab, we only produce a small amount of ammonium nitrate in one go - batch process.
in industry, chemical is produced by a continuous process that means thousands of kilograms can be produced easily