C15. Using our resources Flashcards
How do we reduce the use of resources?
The reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, energy consumption, waste and environmental impacts
What are the advantages and disadvantages of recycling?
Advantages: less acid rain (pollution), metal ore reserves lates longer, conserved energy for extraction saved less mining, quarrying less waste less landfill creates local employment
Disadvantages: collection problems, transport problems, cost of transport, difficult to separate metal from appliances/sort
What is corrosion and how is it prevented
Corrosion is the destruction of materials by chemical reactions with substances in the environment, e.g. rusting, Corrosion can be prevented by applying a coating that acts as a barrier, such as greasing, painting or electroplating. These methods stop the air or water coming into contact with the metal
Describe the sacrificial protection
Some coatings are reactive and may contain corrosion inhibitors or a more reactive metal. If two metals are in contact the more reactive metal will corrode instead of the less reactive one
Describe the compounds and the uses of bronze, brass gold and silver and copper and zinc, aluminium-magnesium and stells?
Alloys
Bronze - an alloy of copper and tin, used for making statues and decorative objects
Brass - an alloy of copper and zinc used for producing water taps and door fittings
Gold used as jewellery is usually an alloy with silver, copper and zinc (The proportion of gold in the alloy is measured in carats, with pure gold being 24 carat, e.g. 18 carat is 75%
Aluminium - magnesium alloys are low density and used in aerospace manufacturing
Steels - alloys of iron that contain specific amounts of carbon and other metals. High carbon steel is strong but brittle. Low carbon steel is softer and more easily shaped. Steels containing chromium and nickel are hard and resistant to corrosion
How are the properties of polymers determined?
The properties of polymers depend on what monomers they are made from and the conditions under which they are made. For example, low density (LD) and high density (HD) poly (ethene) are produced from ethene using different catalysts and reaction conditions
Describe the structures of thermosoftening and thermosetting polymers
Thermosetting polymers do not melt on heating. The polymer molecules are linked to each other by strong cross-links. Thermosoftening polymers soften easily on heating and can then be remoulded, keeping the new shape on cooling.. The polymer molecules are attracted to each other by weak intermolecular forces
How is glass made
Most of the glass we use is soda-lime glass, made by heating a mixture of sand, sodium carbonate and limestone. Borosillicate glass, made from sand and boron trioxide, melts at higher temperatures than soda-lime glass
How are clay ceramics made?
Clay ceramics, including pottery and bricks, are made by shaping wet clay and then heating in a furnace
How are composites formed
Fibres or fragments of one material (reinforcement) are surrounded by a binder/matrix material that holds these fibres/fragments together
Outline the key points of Haber process. Include the use of the product
a) The purified H2 and N2, gasses are passed over Fe catalyst at a high temperature (about 450 degrees) and a high pressure (about 200 atm)
b) Fe speeds up the rate of reaction, so that a lower temperature could be used in the process
c) Some of the hydrogen and nitrogen reacts to form ammonia
d) The reaction is reversible so ammonia breaks down again into nitrogen and hydrogen
e) On cooling, the ammonia liquefies and is removed. The remaining hydrogen and nitrogen are recycled. This means almost no material is wasted
f) Ammonia is used for production of nitrogen-containing fertilisers
The Haber process uses high temperature and pressure conditions. Explain why this is so and why this is a compromise
The conditions are a compromise between rate and the yield:
The reaction is exothermic. An optimum temperature of 450 degrees is used, using a lower temperature would give a higher yield, but the rate of NH3 production would be too slow
A pressure of 200 atm is used. Using a higher pressure would give a higher yield, but would be too expensive because of the cost of energy to produce the high pressure
How are compounds of nitrogen, phosphorous and potassium used?
Compounds of nitrogen, phosphorus and potassium are used a fertilisers to improve agricultural productivity. NPK fertilisers contain compounds of all three elements
How is industrial production of NPK fertilisers achieved?
Ammonia can be used to manufacture ammonium salts. The ammonium sulphate, phosphate and nitrate can be produced by reaction of ammonia with the requisite acid
2NH3 + H2SO4 –> (NH4)2 SO4
2H3 + H3PO4 —> (NH4)3PO4
NH3 + HNO3 —> NH4NO3
How is the phosphate rock utilised in the production of fertilisers?
Phosphate rock is reacted with nitric acid to produce phosphoric acid and calcium nitrate
Phosphate rock can be reacted with sulfuric acid to produce a mixture of calcium phosphate and calcium sulphate
Phosphate rock can be reacted with phosphoric acid to produce calcium phosphate
