BRAINCAKECracking
Fractional distillation gives more of the long-chain fractions than are needed, and not enough of the short-chain fractions such as petrol. Cracking solves this. It breaks long-chain alkanes into shorter-chain alkanes and alkenes.
Cracking breaks C-C bonds, which needs a lot of energy. The products are more useful: short-chain alkanes are used as fuels (petrol), and alkenes such as ethene and propene are used to make polymers and other chemicals.
Thermal cracking uses high temperatures (up to about 900 °C) and high pressure. It gives a high proportion of alkenes.
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More in Alkanes
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- Reforming
- Combustion of Alkanes
- Oxides of Sulfur
- Oxides of Nitrogen
- Catalytic Converters
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All 14 lessons in Alkanes · All Edexcel AS-level Chemistry topics