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Splitting up long-chain hydrocarbons. It is a thermal decomposition reation- breaking molecules down by heating them with a catalyst. Aluminium oxide is the catalyst used. |
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| Alkenes are hydrocarbons which have a double bond between two of the carbon atoms in their chain. |
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Alkenes and Polymerisation |
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This means joining together lots of small alkene molecules to form very large moecules. These long-chain molecules are called polymers. |
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Polymers have different physical properties. The physical properties of a polymer depend on what it is made from. The polymer's physical properties are also affected by the temperature and pressure of polymerisation. |
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| Some fruits and seeds contain lots of oils e.g. Avocados and Olives, Brazil Nuts, peanuts. These oils can be extracted and used for food/ fuel. |
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| They provide a lot of energy. There are other nutrients in oils such as oils from seeds such as oils containing vitamin E. |
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Emulsions can be made form oil and water. They are thicker than oil or water: e.g. mayonnaise and vinegar. |
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You can mix an oil with water to MAKE an emulsion. Emulsions are made up of lots of droplets of one liquid suspended in another. |
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| Biodiesel comes from plant crops which can be harvested every year. You can always keep making Biodiesel and it is made by distilling crude oil. |
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It is biodegradable and its less toxic than regular diesel. It is expensive and difficult to make enough and replace. |
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| Unsaturated oils contain long-chain molecules with lots of carbon atoms. They contain double bonds between some of the carbon atoms in their carbon chains. |
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| Unsaturated vegetable oils are liquid at room temperature. They can be hardened by reacting with hydrogen in the prescence of a nickel catalyst. This is called hydrogenation. |
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Addotoves are used to preserve food and to make it look or taste different to the original. Most additives in the UK had E-numbers in. |
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| Preservatives help food stay fresh. COlourings and flavourings make food look and taste better. Emulsifyers and stabilisers stop emulsions from separating out. |
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| The Evolution of the atmosphere |
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Definition
The Earth's surface was originally moltern for many millions of years. It was so hot that any atmosphere just 'boiled away' into space. Eventually things cooled down a bit and a thin crust formed but volcanoes kept erupting. The volcanoes gave out lots of gas- including CO2, water vapour and nitrogen. The early atmosphere was mostly CO2 with virtually no O2. The oceans formed when the water vapour condensed. |
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