What is a composite?
Made up of a matrix or binder material surrounding reinforcement fibres or fragments e.g concrete
How is low density poly ethene made and what is its property?
Ethene under moderate temperature and high pressure
Flexible
How is high density polyethene made and what is its property?
Ethene under lower temperature and pressure with a catalyst
Rigid
What is a thermosoftening polymer?
Weak forces between individual polymer chains
Can be melted
What are thermosetting polymers?
Monomers form cross links between polymer chains
Strong, hard, rigid and don’t melt
What is rusting?
Corrosion of iron with water and air
What are three methods to prevent rusting?
Barrier - physical e.g paint
Attach a more reactive metal
Galvanisation - coat in more reactive metal - acts as barrier too
What is photo mining?
Soil contains copper
Plant is grown and copper builds up in leaves
Harvested plant is burned - ash contains copper compounds
Displacement reaction with iron to obtain copper
What is bioleaching?
Low grade ore and bacteria
Bacteria produce leachate solution (containing soluble copper compounds)
Pure copper extracted by electrolysis
What is potable water?
Water that is safe to drink
Where is groundwater from and how is it treated?
From underground rocks
Must be filtered and sterilised
Where is salt water from and how is it treated?
Sea water
Must be desalinated
Where is waste water from?
Sewage tratement and agricultural systems
How is ground water treated?
Mesh removes any large debris
Sand and gravel filtration remove any smaller solid bits
Sterilisation - kills of any harmful microorganisms - can be done with chlorine gas, ozone or UV
What are the two method of desalination?
Distillation - boiling
Reverse osmosis - passing through membrane only allowing water particles through
How is waste water treated?
- Screening
- Sedimentation - produces sludge and effluent
- Aerobic digestion of effluent - released back into the environment
- Anaerobic digestion of sludge - natural gas and fertiliser made
How does the haber process work?
Hydrogen from methane is mixed with nitrogen from air
Catalysed by iron
Condensed into liquid ammonia which is removed
Happens at 450 degrees Celsius and 200 atm
Unused reactants are recycled
What is an NPK fertiliser?
Formulations of nitrogen, phosphorus and potassium at the right percentages to help plants grow
How is ammonium nitrate (fertiliser) made?
Ammonia makes nitric acid
Ammonia and nitric acid react to make ammonium nitrate
How is potassium for NPK fertilisers made?
Mix of potassium sulfate and potassium chloride salts
What are the products when phosphate rock reacts with nitric acid?
Phosphoric acid and calcium nitrate
What are the products when phosphate rock reacts with sulphuric acid?
Calcium sulfate and calcium phosphate
What are the products when phosphate rock reacts with phosphoric acid?
Calcium phosphate
