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C2 Science revision flashcards
Cards in this deck (43)
- 1C2- Material ChoicesJessica Brown
- 2Give 2 examples of materialsMetals and polymers
- 3Give an example of a material that comes from a) animals b) plantsa) wool, fur, silk
b) paper, cotton - 4How can alternative materials be made?Synthetic materials (made by chemical synthesis) can be made as alternatives, from materials extracted from the Earths crust
- 5Why do the petrochemical industry refine Crude Oil?To produce fuels, lubricants and raw materials from chemical synthesis
- 6What is crude oil?A raw material in the Earths crust which is thick and black) made from a mixture of hydrocarbons
- 7How is Crude oil separated?Through fractional distillation (by putting it into useful fractions)
- 8What are the stages of fractional distillation?1) Crude oil is heated to evaporate all the hydrocarbons
2) The vapour passes into the fractionating column near the bottom and cools down as it rises
3) Each fraction condenses to a liquid and runs off when it has cooled below its boiling point
4) Any remaining gases leave the tower at the top and are used as gaseous fuels - 9What are intermolecular forces?Forces between molecules that hold them together
- 10What is the relationship between the length of the hydrocarbon and the strength of the force?The longer the hydrocarbon molecules, the stronger the forces are
- 11Because stronger intermolecular forces need more energy, what does this mean for the temperature needed to boil the longer hydrocarbon fractions?The temperature needs to be higher
- 12Is this a strong or weak molecule? HHHHHHHHHHH HCCCCCCCCCCCCCH HHHHHHHHHHHStrong
- 13What does choosing different monomers for the polymerisation process enable?Chemists can produce a range of polymers with different properties
- 14What are the uses of polymerisation?To create a wide range of different materals, which have different porperties therefore have different purposes
- 15Why are natural materials being replaced by polymers? Give an exampleBecause of their superior properties, for example, carrier bags which used to be made of paper are now made of polythene because its stronger and waterproof
- 16What do properties depend on?How their particles are arranged and held together
- 17What are the properties of natural rubber?Long-chain molecules held by covalent bonds. However, the forces between the molecules are weak. The polymer molecules slide over eachother so the material is flexible. It has a low melting point because little energy is needed to separate the molecules
- 18What are the properties of vulcanised rubber?Its a mass of tangled molecules where the atoms within the chains are held by strong covalent bonds. The molecules have cross-links. Vulcanised rubber is hard/rigid as the molecules wont slide over eachother and it has a high melting point as lots of energy is needed to separate the molecules
- 19Where is vulcanised rubber used?To make car tyres
- 20What is cross-links?Strong covalent bonds between the long chain molecules
- 21What is polymerisation?Where small hydrocarbon molecules (monomers) are joined to make very long molecules (polymers)
- 22What is a a) monomer? b) polymer?a) small hydrocarbon molecules
b) long molecules - 23What are the varied properties that different materials have?1) Melting points
2) Strength/weakness
3) Hardness/softness
4) Rigid/flexible - 24What are the properties and uses of a) unvulcanised rubber b) vulcanised rubbera) weak, soft, flexible and used in rubbers
b) strong, hard, flexible and used in tyres, conveyer belts - 25What are the properties and uses of a) polythene plastic b) polystyrene plastica) lightweight, flexible, easily moulded and used in plastic bags and containers
b) lightweight, stiff, waterproof, good thermal insulator and used in thermal flasks, electronics - 26What are the properties and uses of a) nylon synthetic fibres b) polyester synthetic fibresa) lightweight, tough, waterproof and used in clothing and climbing ropes
b) lightweight, tough, waterproof and used in clothing and bottles - 27How big is a nanometre?One millionth of a millimetre
- 28What can nanoscale particles do?1) Occur naturally e.g. in Sea Spray
2) Occur as an accidental result of human activity e.g. particulate carbon released when fuels burn - 29What is nanotechnology?Made deliberately by scientists. The production, study and control of tiny particles on a nanoscale
- 30Why do nanoscale particles have different properties to larger particles?Because nanoscale particles have a larger surface area
- 31Why are nanoparticles used?To modify the properties of other materials
- 32Why are silver nanoparticles used?To give fibres in clothes antibacterial properties e.g. stops socks smelling
- 33What can adding carbon nanotubes to sports equipment do?E.g. can make tennis rackets lighter and stronger
- 34What are the issues surrounding nanotechnology?Scientists have to critically evaluate because nanotechnology is new therefore there is the concern that new materials have not been thoroughly checked and could lead to future health problems
- 35What does increasing the chain length do to a polymer?The forces between the molecules are stronger
- 36What does having cross-links do to a material?Makes it harder as the molecules cant move
- 37Give an example of cross-linkingVulcinization- when sulfur atoms form cross-links between rubber molecules
- 38What is achieved by adding plasticizers to a polymer?Makes them softer and more flexible
- 39What is a plasticizer?A small molecule that sits between molecules and forces the chains apart
- 40Why does a material become more flexible when a plasticizer is used?Because the forces between the chains are weaker so the molecules can move more easily
- 41Where is Plasticized PVC used?Childrens toys
- 42Where is unplasticized PVC (uPVC) used?In window frames
- 43How can a polymer be modified to become stronger and have a higher melting point?By packing molecules closely together to form a crystalline polymer. This means the intermolecular forces are stronger
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- GSCSE Science Flashcards on C2 Science revision flashcards, created by Jessica Brown on 21/03/2015.
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