Organic Chemistry

    Cards (28)

    • Hydrocarbons are compounds made up of carbon and hydrogen atoms only.
    • The general formula for alkanes is CnH2n+2
    • Alkanes have single carbon bonds
    • The alkanes are a homologous series
    • A homologous series is a group of compounds that have similar properties and so react in a similar way due to them having the same functional group
    • Alkanes are saturated meaning each C atom forms 4 single covalent bonds
    • The first 4 alkanes are methane, ethane, propane, butane
    • As chain length increases, the boiling point increases
    • Shorter alkanes are more volatile and longer alkanes are more viscous
    • Shorter alkanes are more flammable
    • Complete combustion only occurs when there is sufficient oxygen
    • Hydrocarbon + oxygen > carbon dioxide + water (+energy)
    • Hydrocarbons are used as fuels due to the amount of fuel released when they combust completely
    • Crude oil is a fossil fuel that is formed from the remains of ancient organisms
    • Crude oil is made up of a mixture of hydrocarbons, mostly alkanes, which can be separated out by fractional distillation
    • Fractional distillation
      • Heat the oil till it turns into a gas
      • There is a temperature gradient in the fractionating column
      • As the gases rise they will condense into a liquid if it is not hot enough and pass out the column
      • Longer hydrocarbons have the highest bps so condense early on (heavy fuel oil: heating oil, fuel oil, lubricating oil)
      • Shorter hydrocarbons will rise up the column and condense later on (Diesel, petrol, kerosene)
      • The shortest hydrocarbons will stay as a gas (Liquified petroleum gas: mostly propane and butane)
    • A feedstock is a raw material used to provide reactants for an industrial reaction.
    • A petrochemical is a substance made from crude oil, via chemical reactions.
    • Cracking is a thermal decomposition reaction when longer hydrocarbons are broken down into smaller molecules so they can be used
    • Catalytic cracking is when the vaporised hydrocarbons are passed over a hot powdered aluminium oxide catalyst which causes them to split apart on the surface of the catalyst
    • Steam cracking is when the vaporised hydrocarbons are mixed with steam and then heated again to a very high temperature cauing them to split apart
    • Alkenes are also a homologous series but are unsaturated as they have a double carbon bond
    • Alkenes are more reactive than alkanes
    • Test for alkenes: they should turn bromine water (orange) to colourless
    • Alkenes can turn into polymers as the double bonds can break to form 2 or more bonds
    • Addition reactions occur between an alkene and another molecule, forming a new compound where both atoms join together
    • Alkenes: ethene, propene, butene, pentene
    • General formula for alkenes: CnH2n
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