Products from Oil
What is the Chemistry of the Cracking of Hydrocarbons?
Cracking of hydrocarbons involves thermal
This means that the large hydrocarbon molecules
break into smaller molecules when they are heated.
The hydrocarbons are boiled and the hydrocarbon gases
are passed over a hot powdered aluminium oxide (Al2O3)
catalyst. The catalyst works by providing
a convenient surface for the cracking to take place.
decane (an alkane with 10 carbons)
can be cracked to produce octane and ethene.
decane octane + ethene.
C10H22(g) C8H18(g) + C2H4(g)
Octane is used as petrol.
Ethene is used in the manufacture of polymers.
Cracking an alkane
produces a smaller alkane plus an
If you add up the number of hydrogen atoms in the above
reaction, you will see that there are 22 on each side.
An alkene is produced because there are not enough
hydrogen atoms to produce two alkanes, after the original
hydrocarbon is cracked. Cracking takes place at about 600 °C.
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