What are the essential elements for growth?
- nitrogen
- potassium
- phosphorous
What do fertilisers do?
- replace missing elements in soils that were used up by the last crop
- helping to increase crop yield , as crops grow bigger and faster
- fertiliser must be dissolved in water before crop roots can take it in
Why is ammonium nitrate and especially good nitrate?
-contains nitrogen from two sources:
ammonia and nitric acid
What are some fertilisers and there components?
- ammonium sulfate, neutralising sulfuric acid with ammonia
- ammonium phosphate, neutralising phosphoric acid with ammonia
- potassium nitrate, neutralising nitric acid with potassium hydroxide
What is the process of eutrophication?
1-fertiliser put on field
2-some inevitably runs off field into rivers and streams#
3-levels of nitrates and phosphates increase
4-algae use nutrients to multiply rapidly creating an algal bloom (carpet of algae), blocking off sunlight to river plants
5-plants cannot photosynthesis, so no food and they die
6-aerobic bacteria feed off plant and multiply
7-as they multiply they use all the oxygen in water
8-everything in the river dies
How is ammonium nitrate prepared?
-titration
1-set up apparatus
2-add few drops of methyl orange indicator to ammonia
3-slowly add nitric acid from burette into ammonia until yellow colour just changes red, swirl flask as you add acid. this is neutralisation and you have ammonia nitrate solution
4-gently evaporate until only a little solution is left to get solid ammonium nitrate crystals
5-crystals not pure yet, they have methyl orange. Note exactly how much nitric acid it took to neutralise ammonia and repeat the titration using that volume of acid with no indicator
What is percentage yield?
- mass of product is the yield of a reaction
- never 100%
- predicted yield is the amount you would get if all reactants were converted into product
- percentage yield is the actual yield in comparison to the predicted yield
How does methyl orange indicator work?
- yellow for alkalis
- red in acids
- colour change means neutalisation
