GCSE: OCR gateway: C2: Fertilisers and crop yields + chemicals from the sea
- Created by: 09tvzutphen
- Created on: 08-04-14 20:34
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- C2
- Fertilisers and Crop Yields
- Growing Crops
- Fertilisers must be dissolved in water before they can be absorbed through plant roots as the dissolved substances are small enogh to be absorbed
- Fertilisers increase crop yield
- Replacing essential elements used by the pervious crop
- Providing extra essential elements
- Providing nitrogen that makes plant protein + increases plant growth
- Replacing essential elements used by the pervious crop
- Eutrophication
- Fertilisers are washed off fields
- Fertilisers increase nitrate and phosphate levels in ponds, rivers, and lakes
- Algae grow rapidly
- Algae block sunlight to oxygen producing plants which die
- Aerobic bacteria use up oxygen in water and feed off dead/decaying plants
- Most living organisms die
- Aerobic bacteria use up oxygen in water and feed off dead/decaying plants
- Algae block sunlight to oxygen producing plants which die
- Algae grow rapidly
- Fertilisers increase nitrate and phosphate levels in ponds, rivers, and lakes
- Exccessive use of fertilisers may contaminate water supplies
- Fertilisers are washed off fields
- Preparing Fertilisers
- Many fertilisers are salts
- So they can be made: ACID + ALKALI = SALT + WATER
- Making fertilisers
- Alkali is titrated with acid using indicator to find quantities
- Acid and alkali have reacted completely to produce a neutral of fertiliser contaminated with indicator solution
- Titration results to repeat experiment using correct quantities
- Dissolved fertiliser heated to evaporate most water off
- Left for remaining solution to crystallise
- Crystals then fitlered off
- Left for remaining solution to crystallise
- Dissolved fertiliser heated to evaporate most water off
- Titration results to repeat experiment using correct quantities
- Acid and alkali have reacted completely to produce a neutral of fertiliser contaminated with indicator solution
- Alkali is titrated with acid using indicator to find quantities
- Many fertilisers are salts
- Growing Crops
- Cemicals from the sea; chemistry of sodium chloride
- Mining and subsidence
- Salt mined in Cheshire
- From ground as rock salt
- Solution mining: water pumped up and saturated salt solution extracted
- Salt mined in Cheshire
- Electrolysis of sodium chloride solution
- Hydrogen made at cathode
- Chlorine made at anode
- Hydrogen and chlorine are reactive
- So have to use inert electrodes so products don't react before they are collected and electrodes do not dissolve
- Na+ ions and H+ ions migrate to cathode
- Electrons gained so reduction
- 2H+ + 2e- = H2
- Electrons gained so reduction
- Cl- and OH- ions go to anode
- Electrons lost so oxidation
- Na+ + OH- = NaOH
- Electrons lost so oxidation
- Uses
- Holdhold bleach
- Solvents
- Plastics
- Paints
- Soaps
- Medicines
- Food additives
- Mining and subsidence
- Fertilisers and Crop Yields
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