Topic 10 - Fertilisers Flashcards
(27 cards)
What is the chemical name for ammonia?
Nitrogen Trihydride
What is its chemical formula?
NH3
What is the shape of an ammonia molecule?
Trigonal Pyramidal
What type of bonding exists in ammonia?
Covalent
List the main properties of ammonia
- Ammonia is a clear, colourless gas at room temperature
- It has a lower density than air
- It dissolves very well in water
- When it dissolves it forms an alkaline solution
- It has a characteristic choking, pungent smell
Write the equation which represents ammonia dissolving / interacting with water
NH3(aq) + H2O(l) <—> NH4+(aq) + OH-(aq)
What would happen if ammonia gas was bubbled through a solution of hydrochloric acid? What type of reaction would this be?
The ammonia gas would react with the acid solution forming a salt called ammonium chloride. This is an example of neutralisation.
Name the industrial process for making ammonia.
Haber Process
Ammonia is a hugely important industrial chemical. Name two products made from ammonia.
- Fertilisers
- Nitric Acid
Name the two elements used to make ammonia in the Haber process.
- Nitrogen
- Hydrogen
Write the word equation for the production of ammonia.
Nitrogen + Hydrogen → Ammonia
What are the raw materials used to provide these elements?
- Nitrogen from the air
- Hydrogen from natural gas
Write the balanced chemical equation for the Haber process using arrows.
N2 + 3H2 ⇌ 2NH3
What does the double arrow tell us about the reaction?
The reaction is reversible
What is the name of the catalyst used?
Iron
What are the conditions used for the Haber Process (pressure, temperature)?
- 450 degrees Celsius
- 200 ATM
- Iron Catalyst
Why are VERY high pressures not used in the process?
Too costly and potentially hazardous
Why is there a need for synthetic fertilisers?
The increasing demand for food for the world’s population means food crop production has to be as high as possible. Cannot be achieved by natural fertilisers alone.
Describe briefly the main properties of a good fertiliser.
A fertiliser should be soluble and contain the key elements essential for plant growth.
Name the three essential elements required by plants for good growth.
- Nitrogen
- Potassium
- Phosphorous
What type of compound is found in a synthetic fertiliser?
Salts
Name three fertilisers produced from ammonia and write their chemical formulae.
- Ammonium Nitrate - NH4NO3
- Ammonium Sulphate - (NH4)2SO4
- Ammonium Phosphate - (NH4)3PO4
Which acid is used to make ammonium nitrate?
Nitric Acid
Which chemical is used as the feedstock to make nitric acid in industry?
Ammonia
