C6.1 - Improving Processes Flashcards
List 3 essential nutrients/minerals plants need to grow & repair
- Nitrogen (N)
- Phosphorus (P)
- Potassium (K)
Name the essential plant nutrients/minerals & typical symptoms of their deficiency
- Nitrogen = poor growth, yellow leaves
- Phosphorus = poor root growth, discoloured leaves
- Potassium = poor fruit growth, discoloured leaves
Fertilisers
= substances that replace elements used by plants as they grow
NPK fertilisers
= fertilisers that provide nitrogen, phosphorus, potassium in water-soluble compounds
Why is it important for these nutrients to be in the water-soluble form
As plant roots can only absorb them in this way
Osmosis
List the compounds in the water-soluble form for each essential element
- nitrogen = nitrate ions (NO3-) / ammonium ions (NH4+)
- phosphorus = phosphate ions (PO43-)
- potassium = potassium ions (K+)
Haber process
= industrial process to make ammonia
Manufactures ammonia from nitrogen & hydrogen
Write the word and symbol equation for the reaction in the haber process
Nitrogen + hydrogen —> ammonia (exothermic)
N2(g) + 3H2(g) —> 2NH3(g)
what are the raw materials for the haber process
- air
- natural gas
- steam
How do the raw materials make nitrogen & hydrogen
- Nitrogen: manufactured by fractional distillation of liquified air
- Hydrogen: manufactured by reacting natural gas (methane) with steam
Conditions chosen for the haber process
- pressure: 200 atmospheres (20MPa)
- temperature: 450ºC
- iron catalyst
Why is the equilibrium yield of ammonia for the chosen conditions in the haber process only 30%
Perfect equilibrium position for temp & pressure
- to increase pressure pressure = too hazardous & expensive
- to decrease temp = too slow rate of reaction, compromise temp
What increases the overall yield of ammonia to 97% in the haber process
Mixture of gases leaving the reaction vessel is cooled = ammonia is liquified
Allows:
- ammonia to be removed
- unreacted nitrogen & hydrogen to be recycled
List the word equations to make the compounds made in a fertiliser factory
- ammonia + nitric acid —> ammonium nitrate
- ammonia + phosphoric acid —> ammonium phosphate
- ammonia + sulfuric acid —> ammonium sulfate
- ammonium nitrate + potassium chloride —> potassium nitrate
Batch process
Chemical process that makes products in limited amounts at different times
Continuous process
Chemical process that makes products in large amounts all the time
How are industrial processes different from in the laboratory (for making fertilisers)
Laboratory
- batch process
+ start with pure substances
Industrial (fertiliser factory)
+ continuous process
- start with raw materials, must be purified before or after
How to make potassium sulfate in a lab:
- put dilute potassium hydroxide solution (KOH) into conical flask
- add few drops phenolphthalein indicator
- add dilute sulfuric acid (H2SO4) from burette / dropping pipette (stop when indicator changes pink to colourless)
- add ‘activated charcoal’ & filter mixture to remove charcoal & attached phenolphthalein
- warm filtrate to evaporate water, leaving potasssium sulfate
(Sulfuric acid titrated with potassium hydroxide)
How to make ammonium sulfate in a lab
- place dilute ammonia solution (NH3) in conical flask
- add few drops methyl orange indicator
- add dilute sulfuric acid (H2SO4) from burette / dropping pipette (stop when indicator changes yellow to red)
- when end-point reached, add extra ammonia solution to ensure reaction complete
- remaining ammonia will evaporate
(Sulfuric acid titrated with ammonia solution)
What fertiliser compounds are made in industrial processes (fertiliser factory)
- ammonium nitrate, NH4NO3
- ammonium sulfate, (NH4)2SO4
- ammonium phosphate, (NH4)3PO4
- potassium nitrate, KNO3
What fertiliser compounds can be made in a laboratory
- potassium sulfate, K2SO4 (aq)
- ammonium sulfate, (NH4)2SO4 (aq)
What is the contact process
Industrial process to make sulfuric acid
Raw materials needed for the contact process (sulfuric acid)
- sulfur
- air (source of oxygen)
- water
3 stages of the contact process
1: sulfur burns in air to produce sulfur dioxide
2: sulfur dioxide & oxygen react together to produce sulfur trioxide
3: sulfur trioxide converted to sulfuric acid
