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Oils, earth and atmosphere summary


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Oils, earth and atmosphere summary

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Oils, earth and atmosphere summary

  1. 1. Oils, Earth and atmosphere summary 2 May 2011
  2. 2. Cracking hydrocarbons <ul><li>Large hydrocarbon molecules are not very useful. They can be cracked into smaller molecules by heating them and passing them over a catalyst. </li></ul><ul><li>The process of cracking involves thermal decomposition and produces some unsaturated hydrocarbons. </li></ul><ul><li>The test for unsaturated hydrocarbons is that they will turn red bromine solution colourless. </li></ul>1
  3. 3. Making polymers from alkanes <ul><li>Plastics are long chain molecules which are produced form unsaturated hydrocarbons. </li></ul><ul><li>The small molecules used to create the long chains are called monomers. </li></ul><ul><li>Once joined together the long chain is called a polymer. </li></ul><ul><li>When a carbon to carbon double bond is broken and the molecules are linked we have an addition polymer. </li></ul>2
  4. 4. The properties of plastics <ul><li>The forces between molecules are called intermolecular forces. The strength of the force in a plastic depends on the monomer used to make the plastic. </li></ul><ul><li>If the force is weak the plastic softens when heated – these are called thermosoftening plastics. </li></ul><ul><li>If the force is strong the plastic does not soften when heated – these plastics are called themosetting plastics. </li></ul>3
  5. 5. New and useful polymers <ul><li>New polymers are being developed all the time – these designer plastics are made to perform in a specific way when used. </li></ul><ul><li>Certain polymers that respond to changes around them are called ‘smart polymers’ – they can regain their origins shape or respond to changes in light and temperature. </li></ul>4
  6. 6. Extracting vegetable oils <ul><li>Plants produce glucose during photosynthesis. The glucose can then be changed into other chemical such as vegetable oils. </li></ul><ul><li>The vegetable oil can be extracted by crushing the plant material (like seeds) or by distillation. </li></ul><ul><li>Vegetable oils are more healthy than animal fats because they contain carbon-carbon double bonds – they are unsaturated. </li></ul><ul><li>The test for unsaturation is adding bromine water which turns colourless if the oil is unsaturated but remain orange if it is saturated. </li></ul>5
  7. 7. Cooking with vegetable oils <ul><li>The boiling point of a liquid depends on the size of the forces between molecules. </li></ul><ul><li>The large size of vegetable oil molecules means that these oils boil at a much higher temperature than water. </li></ul><ul><li>The texture of cooked food depends on the temperature at which it is cooked. So for example potatoes cooked in water and oil have very different textures. </li></ul><ul><li>Unsaturated oils melt and boil at lower temperatures than saturated fats. </li></ul><ul><li>Hydrogenating oils (adding hydrogen to them to remove the carbon-carbon double bond) results in higher melting points and the oil is said to be hardened. </li></ul>6
  8. 8. Everyday emulsions <ul><li>Oil and water do not mix, however if the oil droplets can be made very small and spread out throughout the liquid we have an emulsion. </li></ul><ul><li>In order to make an emulsion an agent which will attract both water and oil molecules is called an emusifier. </li></ul><ul><li>Emulsions made from vegetable oils include salad dressing and ice cream. </li></ul>7
  9. 9. Food additives <ul><li>Chemicals are often added to foods for the following reasons </li></ul><ul><li>(1) to make it look more attractive </li></ul><ul><li>(2) to preserve the food </li></ul><ul><li>(3) to improve the texture </li></ul><ul><li>(4) to control the acidity (pH) </li></ul><ul><li>(5) to improve the flavour. </li></ul><ul><li>Additives can be detected by using a separating method such as chromatography or a mass spectrometer. </li></ul>8
  10. 10. Vegetable oils as fuels <ul><li>It is now possible to make fuels from vegetable material. </li></ul><ul><li>Biodiesel can be made from vegetable oils it is carbon neutral and free from sulphur however there is a huge need for food in the world so using oils in this way is not really a long term solution. </li></ul><ul><li>Ethanol can be made from sugar by allowing the sugar to ferment when yeast is added to the sugar solution. </li></ul>9
  11. 11. Structure of the Earth <ul><li>The Earth has a series of layers. </li></ul><ul><li>The solid crust is 6km to 70km thick . </li></ul>10 <ul><li>The mantle behaves like a solid but does flow slowly, it is very thick – about 3000km. </li></ul><ul><li>The Earth’s core is made up of a mixture of iron and nickel – the outer layer is liquid and the inner layer is solid. </li></ul>
  12. 12. The restless Earth <ul><li>The Earth’s lithosphere (outer shell) is cracked into a number of tectonic plates which are constantly moving. </li></ul><ul><li>The movement of the plates is caused by convection currents in the mantle. The mantle is semi liquid due to the heat produced by radioactive decay in the mantle. </li></ul><ul><li>Earthquakes and volcanoes occur where the tectonic plates meet. Earthquakes take place when the layers slip past each other but are difficult to predict. </li></ul>11
  13. 13. The tectonic plates 12
  14. 14. The Earth’s past atmosphere <ul><li>The Earth’s atmosphere was formed originally by volcanic activity. </li></ul><ul><li>The gases present were carbon dioxide, methane and ammonia. </li></ul><ul><li>As pants formed they consumed the carbon dioxide and produced oxygen. </li></ul><ul><li>At the same time oxygen reacted with methane to form carbon dioxide and water vapour. </li></ul>13
  15. 15. The Earth’s current atmosphere <ul><li>The ammonia reacted with oxygen to form nitrogen and water vapour. </li></ul><ul><li>The Earths present atmosphere consists of 78% nitrogen, 21% oxygen, 0.9% argon (an inert noble gas) and 0.04% carbon dioxide. </li></ul><ul><li>The next slide shows how these changes took place over a long period of time. </li></ul>14
  16. 16. <ul><li>All positions are approximate </li></ul>4500 million Now 3000 million 2000 million 1000 million 500 million 200 million No gases H 2 and He Volcanoes Algae Plants CO 2 NH 3 CH 4 O 2 N 2 H 2 O The changing atmosphere
  17. 17. The Carbon Cycle photosynthesis eaten by respiration respiration respiration Death of plants Death of animals and excretion CO 2 in air Plants contain carbon compounds Detritus feeders and microorganisms feed on dead matter Animals contain carbon compounds 15