Oils

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  • Oils
    • Cracking crude oil
      • Long-chain hydrocarbons
        • Form thick gloopy liquids like tar
        • Made smaller by cracking
          • Some products are useful
          • Produces things like ethane - used for plastics
      • How it's done
        • Thermal decomposition reaction
        • Heat hydrocarbon to vaporise it
          • Vapour passed over powdered catalyst at temp of    400-700*C
            • Long chain molecules split on surface
        • Uses aluminium oxide catalyst
      • Products
        • Unsaturated hydrocarbons - alkenes
          • H         H            \         /              C = C            /         \      H       H
    • Plant oils
      • Extract oil from plants
        • Used for food and fuels
        • Crushed the pressed to get oil out
        • Oil can be seperated using a centrifuge - like a spin dryer
        • Solvents can be used to extract it
        • Distillation - refine oil and remove water, solvents + impurities
      • Vegetable oils
        • Used in fuels
        • Provide lots of energy
        • Other nutrients like vitamin E
        • Contain essential fatty acids - metabolic processes
        • Good for cooking
          • Higher boiling point than water
          • Cooks at faster speed
          • Different flavour
          • Carries flavour
          • Increase energy we get from eating
        • Produce fuels
          • Processed
          • Provide lots of energy
          • Biodiesel
        • In food can affect health
          • Unsaturated fats reduce amount ofbllood cholestorol
          • Partially hydrogenated vegetable oil increases cholstorol
            • Bad for you
        • Cooking food in oil makes it more fattening
      • Unsaturated oils
        • C = C bond
        • Decolourise in bromine water
        • Monounsaturated - one C = C bond
        • Polyunsaturated fat - multiple C = C bonds
        • Can be hydrogenated
          • Liquid at room temp
            • Add hydrogen - hardened
              • Hydrogenatio-n
          • Hydrogenated oils have higher melting boints - more solid at room temp
            • Useful as spreads
              • End up with a lot of trans fats - no evidence they are bad for you
    • Emulsions
      • Made from oil and water
        • Oil doesn't dissolve in water
        • Water in oil or oil in water
      • Lots of droplets of a liquid suspended in another liquid
      • Thicker than the two liquids used
      • Some foods contain emulsifiers to help water and oil mix
        • Pros
          • Stop emulsions from separating- longer shelf life
          • Produce food with lower fat but still taste good
        • Cons
          • People can be allergic

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