Organic chemistry


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Organic chemistry

  1. 1. Formation of oil and gas 21/03/20121) Layers of 2) Layers of 3) The heat and ________ fromdead sea _____ __________ these rocks, along with thesettle on the rock build up on absence of ______, mean that oilseabed. top. and gas are formed over ______ of years. Words – sedimentary, millions, oxygen, creatures, pressure
  2. 2. Hydrocarbons and crude oil 21/03/2012 Crude oil is a mixture of HYDROCARBONS (compounds made up of carbon and hydrogen). Some examples: H H Longer chains mean… Increasing length H C C H H H 1. Less ability to flow Ethane 2. Less flammable H H H HH C C C C H 3. Less volatile H H H H 4. Higher boiling point Butane
  3. 3. Fractional distillation 21/03/2012Crude oil can be separated by fractional distillation. The oil is evaporatedand the hydrocarbon chains of different lengths condense at differenttemperatures: Fractions with low boilingpoints condense at the top Fractions with high boilingpoints condense at the bottom
  4. 4. Cracking 21/03/2012Shorter chain hydrocarbons are in greater demand becausethey burn easier. They can be made from long chainhydrocarbons by “cracking”: Butane Ethane For example, this bond can be “cracked” to give two of these: Ethane
  5. 5. Cracking 21/03/2012 This is a THERMAL DECOMPOSITION reaction, with clay used as a catalystCracking is used to produce plastics such as polymers and polyethanes. Thewaste products from this reaction include carbon dioxide, sulphur dioxideand water vapour. There are three main environmental problems here:1) Carbon dioxide causes the _________ effect2) Sulphur dioxide causes _____ _____3) Plastics are not _____________
  6. 6. Alkanes 21/03/2012Alkanes are SATURATED HYDROCARBONS. What does thismean? HYDROCARBONS are molecules that are made up of hydrogen and carbon atoms SATURATED means that all of these atoms are held together by single bonds, for example: Ethane ButaneAlkanes are fairly unreactive (but they do burn well).
  7. 7. Alkenes 21/03/2012Alkenes are different to alkanes; they contain DOUBLECOVALENT bonds. For example:ALKANES ALKENES Ethane Ethene Butane ButeneThis double bond means that alkenes have the potential to joinwith other molecules – this make them REACTIVE. We cantest for alkenes because they turn bromine water colourless.
  8. 8. Monomers and Polymers 21/03/2012 Here’s ethene again. Ethene is called a MONOMER because it is just one small molecule. We can use ethene to make plastics… EtheneStep 1: Break the double bondStep 2: Addthe moleculestogether: This molecule is called POLYETHENE, and the process that made it is called POLYMERISATION
  9. 9. Another way of drawing it… 21/03/2012Instead of circles, let’s use letters… H H H H H H H H C C C C C C C C H H H H H H H H Ethene Ethene Poly(e)thene General formula for addition polymerisation: n C C C C n H CH3 H CH3e.g. n C C C C H H H H n