Cracking
Cracking is a form of thermal decomposition, which breaks long chain hydrocarbons, many of which are not very useful, into shorter molecules by heating them. Many of the substances with longer molecules produced from the fractional distillation of crude oil are cracked; for example, naphtha is cracked to produce gasoline. Cracking also produces extra alkenes, which are needed for making plastics.
In industrial cracking, vaporized hydrocarbons are passed over powdered aluminum oxide catalyst at a temperature of 400°–700°C. Since any of the C–C bonds in a molecule can break, the result is a mixture of products, although the conditions for the reaction are chosen to favor some products over others.
