Flashcards
C2
Cards in this deck (32)
- 1Where does rubber come from?Some rubber (e.g. car tyres) comes from the sap of the rubber tree but other rubber (e.g wetsuits) is synthetic and made in a factory as you can control its properties making it suitable for its purpose this way.
- 2What are man clothes made from and why?Polyester and nylon as the properties can be changed e.g. make the water-proof, super-stretchy or sparkly
- 3What are the properties of materials?1) Melting Point
2) Strength
3) Stiffness
4) Hardness
5) Density - 4What are the different types of strength?Tensile strength - how much a material can resist a pulling force e.g. ropes need this.
Compressive strength - how much a material can resist a pushing force e.g. bricks need this. - 5Whats the difference between stiffness and hardness?Stiffness is how hard it is to bend hardness is how hard it is to cut.
- 6What is density?A materials mass per unit volume.
- 7What are the properties of plastic?- Hard, strong and stiff
- Fairly low density (good for lightweight goods)
- Some are mouldable
e.g. cases for televisions, computers and kettles. - 8What are the properties of rubber?- Strong but soft and flexible
- Mouldabe
e.g. rubber car tyres. - 9What are the properties of nylon fibres?- Soft and flexible
- Good tensile strength
e.g. ropes and clothing fabric - 10Explain how the materials record are made from have changed over the years?Grammaphine records were made from materials such as paper slate and wax but these broke very easily. Next vinyl was used as it is strong and flexible so less easy to break. Now CD's are used and are made from polycarbonate which is a very strong plastic.
- 11What is crude oil made from?Hydrocarbons
- 12What changes the properties of hydrocarbonsThe length of the carbon chain
- 13Why do big molecules have higher boiling points than small molecules?The strong covalent bonds within the hydrocabon is stronger than the intermolecular forces between diferent hydrocarbon molecules so when crude oil is heated the molecules are supplied with energy that breaks the intermolecular forces but not the covalent bonds. Intermolecular forces are much stronger in bigger molecules so smaller molecules have lower boiling points.
- 14What has to happen to make crude oil useful?You have to separate it which is called refining and it is done by fractional distillation.
- 15How is fractional distillation done?Hydrocarbons are heated up and seoerated into different groups called fractions with similar boiling points. As hydrocarbons have similar boiling points if they are similar lengths. The use of the hydrocarbon depends on the length of the molecule chains (see page 21)
- 16What are some uses of crude oil?The petrochemical industry refines crude oil for fuels and lubricants. Most of the hydrocarbons in crude oil are used to produce fuels. A small amount is used to make new compounds (this is called chemical synthesis) for use in things such as plastics and medicines. Less useful hydrocarbons are split apart to make more useful hydrocarbons and ethane which is useful for making plastics.
- 17Explain polymerisation.When loads of small molecules called monomers link together to make a very long chain called a polymer e.g. plastic. They're usually carbon based. Under high pressure many small molecules "join hands" (polymerise) to form long chains called molecule
- 18What happens in polymerisation when a range of monomers are used?A range of polymers will be made which have different physical properties e.g. some are stronger, some are stretchier, some are more easily moulded e.t.c.
- 191) What are strong rigid polymers used for? 2) What are light stretchable polymers used for?1) Plastic milk bottles (made from high density polythene).
2) Plastic bags and squeezy bottles (made from low density polythene). It has a low melting point so isn't good for anything hot. - 201) What is PVC used for? 2) What is polystyrene foam used for? 3) What are polymers such as melamine resin and polypropene used for?1) It is strong and durable and can be made either rigid (for window frames and piping) or stretchy (for synthetic leather).
2) Packaging and disposable coffee cups as the trapped air in the foam makes a good thermal insulator.
3) Plastic kettles as they're heat-resistant - 21What have synthetic fibres like nylon and polyester replaced and what are the advantages and disadvantages of this?Cotton, wool or silk fabrics. Synthetic fibres tend to be lighter, more durable, water-resistant and cheaper. However they aren't breathable so tend to be more uncomfortable.
- 22What has rigid PVC replaced and what are the advantages and disadvantages of this?Wood as a material for window frames. It is good as it is weather-resistant, strong and durable which makes windows more secure and means the frames don't need painting every few years. However they don't look as nice as wooden ones.
- 23What do polymers properties depend on?The chemicals its made from and the way polymer chains are arranged. If the polymers chains are packed close together the material will have a high density. If the polymer chains are spread out the materials will have a low density.
- 24What is the arrangement of polymers with different density?If the polymers chains are packed close together the material will have a high density. If the polymer chains are spread out the materials will have a low density.
- 25How do the forces between different chains affect the properties of the polymer?Chains held together by weak forces are free to slid over each other so the plastic can be stretched easily and will have a low melting point. Plastics with stronger bonds between the polymer chains will have higher melting points and can't be easily stretched. This is because the crosslinks hold the chains firmly together so more energy is needed to break them apart (look at pics on page 23).
- 26What can be done to chemically modify polymers and what change does it have to their properties?1) Increase chain length so the polymers are stiffer and have higher melting points.
2) Adding cross links so the chains are chemically bonded together making it stiffer, stronger and heat-resistant.
3) Add plasticine which works by getting in between polymer chains and reducing the forces between them this makes the polymer softer and easier to shape.
4) Making it more crystalline so has a higher density, stronger and have a higher melting point. - 27What is a crystalline polymer?It is a polymer which has straight chains with no branches so the chains can fit close together.
- 281) What are nanoparticles? 2) What is nanotechnology?1) Tiny particles, 1-100 nanometres across
2) The branch of technology that deals with the making and use of nanoparticles. The structures dealt with in nanotechnology are are only as big as one molecule. - 29What are examples of naturally occurring or accidently produced nanomaterials?Seaspray - produces nanoscale salt particles which are present in the atmosphere.
Combustion - when fuels are burnt nanoscale soot particles are produced. - 30Give examples of when nanoparticles have been added to materials and why this has been done.1) Nanoparticles are added to plastics in sports equipment to change the properties e.g. added to tennis rackets golf balls e.t.c. to make the plastic stronger and more durable without adding weight.
2) Silver nanoparticles added to polymer fibres used to make surgical masks and wound dressing as it gives the fibres antibacterial properties. - 31Why do nanoparticles have different properties to larger particles of the same material?They are much smaller so have a larger surface area-to-volume ratio e.g. silver nanoparticles can kill bacteria where as normal silver particles have a smaller surface area-to-volume ratio so can't.
- 32What are the disadvantages of nanoparticles?The way they effect your body isn't fully understood so it is important that these products are tested thoroughly. Some worry that products containing nanoparticles have been released before we know the long-term effects. Therefore it is argued that products containing nanoparticles should be clearly labelled so consumers can choose whether to buy them.
Information
- Description
- GCSE Chemistry Flashcards on C2, created by rhian.gregory109 on 26/04/2015.
- Created by
- rhian.gregory109
- Views
- 1
- Rating