BRAINCAKEAlkanes
Revision notes for Alkanes in Edexcel Chemistry (8CH0). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- AlkanesAlkanes are saturated hydrocarbons: they contain only carbon and hydrogen, joined by single covalent bonds.
- Alkanes from Crude OilCrude oil is a mixture of hydrocarbons, mostly alkanes, with chains from one to over fifty carbon atoms.
- CrackingFractional distillation gives more of the long-chain fractions than are needed, and not enough of the short-chain fractions such as petrol.
- ReformingReforming converts straight-chain alkanes into branched-chain alkanes and cyclic hydrocarbons (cycloalkanes and arenes such as benzene).
- Combustion of AlkanesAlkanes are used as fuels because their combustion is very exothermic and they are easy to transport and store.
- Oxides of SulfurFossil fuels such as coal, crude oil and natural gas contain small amounts of sulfur compounds as impurities.
- Oxides of NitrogenOxides of nitrogen, written together as NOx, are pollutants from vehicle engines and power stations.
- Catalytic ConvertersA catalytic converter is fitted to a vehicle exhaust to change the most harmful pollutants into less harmful gases.
- Alternative FuelsMost of the world's energy still comes from fossil fuels.
- BiofuelsA biofuel is a fuel made from biomass: plant or animal material from recently living organisms.
- Biofuels vs Fossil FuelsBiofuels are often described as better for the environment than fossil fuels, but the comparison needs care.
- Bond BreakingA covalent bond is a shared pair of electrons.
- Free-Radical Substitution of AlkanesAlkanes react with chlorine or bromine in ultraviolet (UV) light.
- Further SubstitutionFree-radical substitution does not stop at one substitution.