Crude oil, alkanes and cracking

The idea

Crude oil is a mixture of hydrocarbons, mostly alkanes (general formula CₙH₂ₙ₊₂: methane, ethane, propane, butane). Fractional distillation separates it into fractions with similar boiling points. As chain length increases, boiling point and viscosity increase and flammability decreases. Complete combustion gives carbon dioxide and water. Cracking breaks long-chain hydrocarbons into shorter, more useful alkanes and alkenes, using a catalyst or steam. Alkenes turn bromine water from orange to colourless.

1. Use CₙH₂ₙ₊₂ for alkanes.
2. Link chain length to properties.
3. Write cracking equations with atoms balanced.

Watch out Cracking is needed because there is more demand for short-chain fuels than crude oil supplies.