C2 Material Choices

1. C2 Material Choices 11/10/2014 This PowerPoint supports the C2 topic from the 2011 OCR 21st Century course W Richards

2. C2.1 Properties of Materials Q. For each of the following materials describe what properties the material needs to have and why…

3. Properties of materials • Plastic (polythene) • Light • Flexible • Easily moulded

4. Properties of materials • Plastic (polystyrene) • Light • Rigid • Good insulation

5. Properties of materials • Nylon • Light • Tough • Waterproof

6. Properties of materials • Polyester • Light • Tough • Waterproof

7. Properties of materials • Unvulcanised rubbers • Low tensile strength • Soft • Flexible

8. Properties of materials • Vulcanised rubbers • High tensile strength • Hard • Flexible

9. C2.2 Crude Oil

10. Using Different Materials Cotton from plants Silk from silkworms Wood and paper from trees We use a variety of materials from a variety of different places: These are all “natural” materials – we can also use synthetic (man-made) ones like plastics – these are often made from materials from within the Earth like crude oil.

11. C2.4 Nanotechnology

12. Chemical formulae Na Cl K I O O O The chemical formulae of a molecule or compound is simply a way of showing the ratio of atoms in it. For example… = sodium chloride (NaCl) = potassium iodide (KI) = potassium nitrate (KNO3) K N

13. Chemical formulae • Try drawing these: • Water H2O • Carbon dioxide CO2 • Calcium sulphate CaSO4 • Magnesium hydroxide Mg(OH)2

14. Simple chemical reactions O O O O O O O H Cl H Cl Mg Mg Cl H H Cl Mg Mg + Magnesium oxide + Hydrochloric acid Magnesium chloride Cu Cu + Mg MgO + + CuSO4 2HCl S S MgCl2 O O O + Magnesium + Copper sulphate Copper + Cu Water H2O Magnesium sulphate MgSO4 Notice that the number of atoms on each side of the equation is the same!

15. Hydrocarbons and crude oil H H C C H H H H Ethane Increasing length H H H H C C C C H H H H H H Butane Crude oil is a mixture of HYDROCARBONS (compounds made up of carbon and hydrogen). Some examples: These different “lengths” are called “_______” and most of them are used as _____. Some are used to make materials such as _______. Longer chains have higher _____ points. Words – boiling, fractions, plastics, fuels

16. Fractional distillation Fractions with low boiling points condense at the top Fractions with high boiling points condense at the bottom Crude oil can be separated by fractional distillation. The oil is evaporated and the hydrocarbon chains of different lengths condense at different temperatures:

17. Forces between molecules Weak force of interaction here Longer molecules = stronger force of attraction, leading to higher boiling points due to the molecules needing more energy to “pull” them away from each other.

18. Polymers H H C C H H Ethene This molecule is called POLYETHENE (i.e. polythene), and the process that made it is called POLYMERISATION Here’s ethene. Ethene is called a MONOMER because it is just one small molecule. We can use ethene to make plastics… Step 1: Break the double bond Step 2: Add the molecules together:

19. C2.3 Molecular Structure

20. Uses of addition polymers Poly(ethene) Poly(propene) Poly(styrene) Poly(chloroethene), PVC

21. Structure of Plastics 1) Some plastics have ____ intermolecular forces between each molecule – these have __ melting points and can be ________ easily 2) Some plastics have _____ forces between each molecule. These have ____ melting points and are ____. Words – high, low, strong, weak, stretched, rigid

22. Forces between molecules As we’ve already said, longer molecules have stronger forces of attraction between them. This tends to lead to longer chain plastics being: • Stronger • Stiffer • Harder • More difficult to melt (i.e. higher melting point)

23. Modifying Plastics Polymers can be modified in a number of ways: • Increasing the chain length • ...making it stronger • 2) Crosslinking • ...making it harder • 3) Plasticizing • ...making it softer and more flexible • 4) Packing more closely (a crystalline polymer) • ...making it stronger and more dense

24. Nanotechnology Task: To find out what nanotechnology is and what it is used for • What is nanotechnology? • Define the terms nanoparticle and nanocomposite • Gives some examples of its uses • Describe some of the future uses of this technology • Describe some of the ethical concerns over this technology

25. Nanotechnology Definition: Nanotechnology is a new branch of science that refers to structures built from a few hundred atoms and are 1-100nm big. They show different properties to the same materials in bulk, partly because they also have a large surface area to volume ratio and their properties could lead to new developments in computers, building materials etc.

26. How nanoparticles are formed They can occur naturally in sea spray They can also be formed during combustion Or they can be formed by grinding down materials Nanoparticles can be formed by a number of methods:

27. Two examples of nanotechnology E-coli affected by silver nanoparticles Normal e-coli The “Nano Carbon Pro” tennis racket uses nanoparticles to increase its strength. Silver nanoparticles can be used to give fibres antibacterial properties – look at what they do to e-coli bacteria:

28. Nanoscience and health Nanoparticles are obviously very small and, as we have said, have a large surface area to volume ratio. This makes them useful but can also make them dangerous. Nanoparticles could easily pass through a cell membrane: I’m going to die… How do these health concerns affect the development of nanotechnology?

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