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C2

Miraal Ali SCIENCES GCSE Inglés 35 fichas

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  1. 1What are Rubber, Plastics and Fibre used for?- Rubber used to make car tyres as it is hard and elastic
    - Fibres are used to weave cloth into clothes
    - Plastics keep their shape, when moulded into objects like washing-up bowls
  2. 2Melting point?The temperature needed to turn a solid into a liquid
  3. 3Tensile strength?The force needed to break a material when stretching it
  4. 4Comprehensive strength?The force needed to crush a material when it is being squeezed
  5. 5StiffnessThe Force needed to bend a material
  6. 6HardnessHow well a material stands up to wear. Hardness can be compared by scratching two materials
  7. 7DensityThe mass of given volume of a material. Compares how heavy something for its size.
  8. 8Why are repeats needed?A single result may vary, so repeats are needed
  9. 9What do u call a result which is very different?An outlier - incorrect result
  10. 10Why do scientists calculate the mean/average of a range of resultsCalculating the mean ( average ) of results is a good way to find the true value.
    - Many measurements are needed to find the true value
  11. 11What is range ?The Range is the smallest to largest results, ( excluding outliers ).
  12. 12What do Errors do?Errors in measurement produce variations in data
  13. 13When can Outliers be discarded?Outliers can only be discarded if there has been an error in the measurements
  14. 14Natural Materials?Materials from living things which need little processing e.g. cotton and paper from plants, silk and wool from animals
  15. 15Synthetic Materials?Are Manufactured by chemical reactions using Raw materials
  16. 16Why have Synthetic Materials replaced Natural Materials?- Synthetic materials can be designed to make particular properties
    - Synthetic materials are cheaper and needed in small quantity
    - Natural Materials are in short supply
  17. 17What is crude oil?Crude oil is a mixture of Hydrocarbons.
  18. 18What are crude oil used for?- 90% of crude oil is used as fuel
    - 3% used to synthesis other chemicals
  19. 19How is crude oil separated through fractional distillation?- Crude oil mixture is added into a furnace then heated up. The Temperature needed to Heat it up into a gas ( Boiling point ) determines how which fraction (High or Low) the gases go. The distillation tower gets cooler as it gets higher. The higher it gets the lower the boiling point thus the smaller the molecule chains, weaker the forces between molecules. The Gas molecules condense into Liquid. Liquids with similar boiling points, we call these fractions
  20. 20Investigating Boiling Points?- There are inter-molecular forces between the molecules, which hold them together.
    - The stronger these forces, the higher the boiling point.
    - As hydrocarbon chains increases, the forces between the molecules increases.
    - Larger molecules need more energy to break them out of liquid to form a gas, so have higher boiling points
  21. 21Making Polymers?- Polymer is a large molecule made by joining many small molecules called 'monomers'.
    - Polymer is made by a process called polymerisation
    - Ethene is a monomer used to make Polyethene
    -Different monomers produce different polymers, giving different properties
  22. 22Examples of Polymers replacing old materials?- Plastic buckets
    - Carbon Fibre Tennis rackets
  23. 23Changing of Polymers?- Polymer chains can be altered by replacing hydrogen atoms with other groups of atoms.
    - Each new polymer has its own properties
  24. 24Attractive Molecules/ Forces- Small forces attract molecules together. Its what holds them together.
    - The forces are strongest when molecules are close together
    - The Stronger the force :
    1. More energy needed to separate the molecules
    2. The higher the boiling/ melting point
  25. 25What are LDPE polymers?Low Density Polyethene has long molecule chains with branches.
    - The branches keep the molecule chains apart, so forces between different molecules are weak.
    - Thus it gives properties e.g. : Low Melting Point, Flexibility , Soft
  26. 26What is a HDPE polymer?High Density Polyethene is a polymer with long chains but no branches, thus the molecules are aligned close together. HDPE is much stronger an is used to make long-lasting items which are hard and stiff e.g. water pipes.
    - HDPE has a higher degree of crystallinity
  27. 27What does high crystalline mean?- HDPE has a higher degree of crystallinity. This means there are lots of areas with regular patters in the way molecules line up.
    - Higher Crystalline polymers are strong with high melting points but can be brittle
  28. 28Improving polymers?- Making polymer chains longer makes it stronger, more energy needed to separate them, higher boiling/boiling point.
    -Crystallinity can be increased by removing branches between the main polymer chains and making the chains flat as possible. This is so that the polymer chains can align neatly
    - Drawing Polymers through tiny holes when heated makes the molecule chains line up, increasing the crystallinity thus forming a higher tensile strength.
  29. 29Plasticisers?They are used to make polymers softer. They are small molecules inserted between the polymer chains, to weaken up the forces thus making the polymer more flexible.
  30. 30Plasticised PVC?Plasticised PVC is still hardwearing and waterproof, but also made flexible, making it a suitable material for rain coats.
  31. 31ThermoplasticsSoft when heated and can be moulded into any shape
  32. 32Thermosetting-plastics ?Thermosetting-plastics do not soften when heated. They contain cross-links which are branches that connect the polymer chains together.
  33. 33Nanoparticles?Are 1 millionth of millimetre. They can be used as catalyst because of their large surface area, increasing the site of reactions to occur
  34. 34Using Nanoparticles?- Silver Nanoparticles are extremely good at killing bacteria. They can be: woven into socks or added to fibres, put into wound dressings, put into plastics that are made into food containers.
    - Titanium oxide Nanoparticles are put into sun screen. They make sun screen transparent.
  35. 35Composites ?Nanoparticles can be mixed with other materials e.g. Metals, Ceramics , Plastics. These combined materials are called composites.
    - Composite materials are stronger and harder wearing.
    - Thus adding Nanoparticles to :
    1. Plastic Sports Equipment make it stronger
    2. Tennis balls to make them bouncier
    3. Rubber used in tyres to make it more hard wearing

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GCSE SCIENCES Fichas sobre C2, creado por Miraal Ali el 14/05/2016.
Creado por
Miraal Ali · may 2016
Actualizado
7 mar 2018
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