A-level Chemistry/OCR (Salters)/Developing Fuels

thumb|right|300px|Benzene is an aromatic hydrocarbon. Instead of having three short double bonds and three long single bonds (above, left), it has six medium-length bonds (above, right). A double bond is really two bonds, with two electrons in each bond, so four electrons in total in a double bond. Two electrons from each double bond in benzene (if the double bonds really existed, which they don't) are smeared over all six carbon atoms. Whenever electrons are not confined to a bond between just two atoms, they are called declocalised electrons. Developing Fuels is the second unit in the Salters Advanced Chemistry course. Chemical Storylines sections DF1: Petrol is popular DF2: Getting energy from fuels DF3: Focus on petrol DF4: Making petrol − getting the right octane rating DF5: Trouble with emissions DF6: Tackling the emissions problem DF7: Changing the fuel DF8: Hydrogen − a fuel for the future? DF9: Summary Chemical Ideas sections 4.1 Energy out, energy in 1.3 Using equations to work out reacting masses 4.2 Where does the energy come from? 12.1 Alkanes 3.4 Structural isomerism 13.2 Alcohols and ethers 4.3 Entropy and the direction of change Activities DF1.1 Which fuel for the future? DF1.2 Measuring the enthalpy change of combustion of different fuels DF1.3 Comparing the enthalpy changes of combustion of different alcohol DF2.1 Using spreadsheets to calculate enthalpy changes of combustion DF2.2 Making notes DF3.1 How do physical properties change along the alkane series? DF3.2 Comparing winter and summer petrol blends DF3.3 Auto-ignition in a test-tube DF4.1 Modelling and naming alkanes DF4.2 The octane numbers of different alkanes DF4.3 Using zeolites DF4.4 Cracking alkanes DF4.5 A closer look at alcohols DF4.6 Blend your own DF4.7 Why do hydrocarbons mix? DF4.8 Petrol - pulling it all together DF5 What happens to the sulphur? DF9 Check your notes on Developing Fuels External links DF unit map DF Check Your Notes