C1 Crude oil and Fuels

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  • Crude oil and fuels
    • Fractional distillation
      • Crude oil is a mixture of hydrocarbons
        • A mixture consists of two or more elements or compounds that aren't chemically bonded together
        • Crude oil is a mixture of many different compounds
          • A mixture consists of two or more elements or compounds that aren't chemically bonded together
          • Most of the compounds are hydrocarbon molecules
            • Hydrocarbons are basically fuels such as petrol and diesel
              • Crude oil is a mixture of hydrocarbons
                • Crude oil is a mixture of many different compounds
                  • Most of the compounds are hydrocarbon molecules
                    • Hydrocarbons are basically fuels such as petrol and diesel
                      • They're made of just carbon and hydrogen
                  • Because the compounds aren't chemically bonded together, they all keep their original properties
                    • This includes their condensing points
                      • This means that the separate compounds in the mixture can be separated using fractional distillation
                    • The properties of a mixture are just a mixture of the properties of the separate parts
                  • Crude oil is a fossil fuel
                    • It's formed over millions of years from the buried remains of plants and animals
                • They're made of just carbon and hydrogen
            • Because the compounds aren't chemically bonded together, they all keep their original properties
              • This includes their condensing points
                • This means that the separate compounds in the mixture can be separated using fractional distillation
              • The properties of a mixture are just a mixture of the properties of the separate parts
            • Crude oil is a fossil fuel
              • It's formed over millions of years from the buried remains of plants and animals
        • Hydrocarbons
          • Properties
            • Some properties of hydrocarbons depend on the size of their molecules. These properties influence how hydrocarbons are used as fuels
              • The shorter the molecules, the less viscous it is
                • The really gloopy, viscous hydrocarbons are used for lubricating engine parts and covering roads
              • The shorter the molecules, the more flammable the hydrocarbon is
              • The shorter the molecules, the more volatile they are, so the lower the boiling point
                • The volatility helps decide what the fraction is used for
                  • The refinery gas fraction has the shortest molecules, so it has the lowest boiling it - it's a gas at room temperature
                    • This makes it ideal for using as bottled gas
                      • It's stored under pressure as liquid in 'bottles', and when the tap on the bottle is opened, the fuel vaporises and flows to the burner where it's ignited
          • Hydrocarbon fuels
            • Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur
              • The gases released into the atmosphere when a fuel burns may include carbon dioxide, water (vapour), carbon monoxide, sulfur dioxide and oxides of nitrogen
                • Solid particles (particulates) may also be released
                  • These may contain soot (carbon) and unburnt fuels
                  • This happens with partial combustion - when there isn't enough oxygen and the fuel doesn't burn
                  • These particulates cause global dimmming
                    • Global dimming is the decrease in how much sunlight is reaching the surface of the Earth
                    • They reflect sunlight back into space, or help to prduce more clouds that reflect sunlight back into space
                • Hydrocarbon + oxygen --> carbon dioxide + water vapour
                • Sulfur dioxide and oxides of nitrogen cause acid rain
                  • The gases mix with clouds to form dilute forms of their acids, which then fall as acid rain
                  • Sulfur can be removed from fuels before they are burned, for example in vehicles
                  • Sulfur dioxide can be removed from the waste gases after combustion, for example in power stations.
                • Carbon dioxide causes global warming
            • The combustion of hydrocarbon fuels releases energy
              • During combustion the carbon and hydrogen in the fuels are oxidised
        • Alternative fuels
          • Biofuels, including biodiesel and ethanol, are produced from plant material
            • There are economic, ethical and environmental issues surrounding their use
            • ETHANOL can be produced from plant material so is known as a biofuel
              • It's made by fermentation of plants and is used to power cars in some places
                • It's often mixed with petrol to make a better fuel
              • The CO2 released when it's burnt was taken in by the plant as it grew, so it's carbon neutral
                • The only other product is water
              • Engines need to be converted before they'll work with ethanol fuels
              • Ethanol fuel isn't widely available
                • There are worries that as demand for it increases farmers will switch from growing food crops to growing crops to make ethanol - this will increase food prices
            • BIODIESEL can be produced from vegetable oils such as rapeseed oil and soybean oil, so it is a biofuel
              • Biodiesel can be mixed with ordinary diesel fuel and used to run a diesel engine
                • This means engines don't need to be converted to use it
              • It's carbon neutral
              • It produces much less sulphur dioxide and particulates than ordinary diesel or petrol
              • It's expensive to make
              • We can't make enough to completely replace diesel
                • Because of this, it could increase food prices in the same way ethanol could
          • HYDROGEN GAS can be used to power vehicles
            • The hydrogen comes from electrolysis of water - there's plenty of water about but it takes electrical energy to split it up
              • This energy can come from a renewable source, e.g. solar
            • Hydrogen combines with oxygen in the air to form just water - so it's very clean
            • You need a special, expensive engine and hydrogen isn't widely available
            • You still need to use energy from another source to make it
            • It's hard to store because it's explosive

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