4.10.2/3 LCA and using materials (might come up) Flashcards
Describe the stages of LCAs
LCAs carried out to assess the environmental impact of products in each of these stages
Extracting and processing raw materials
Manufacturing and packaging
Use and operation during its lifetime
Disposal at the end of its useful life, including transport and distribution at each stage
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
A: Less acid rain (pollution) Metal ore reserves last longer Less mining/quarrying Less waste Less landfill Creates local employment
D: Collection problems Transport problems Cost of transport Difficult to separate metal from appliances / sort
What is corrosion and how is it prevented
The destruction of materials by chemical reactions with substances in the environment eg 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 eg zinc is used to galvanise iron and when scratched, provides sacrificial protection because zinc is more reactive than iron
Describe the compounds and the uses of bronze, brass, gold and silver and copper and zinc, aluminium-magnesium and steels
Bronze - 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 allow with silver, copper and zinc
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 and high density polyethene 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
Heating a mixture of sand, sodium carbonate and limestone — soda lime glass
Sand and boron trioxide - melts at higher temps – borosillicate glass
How are clay ceramics made
Shaping wet clay and then heating in a furnace
How are composites formed
Fibres or fragments of one material are surrounded by a binder/matrix material that holds these fibres together
