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Science

Polymers and ethanol from oil

In order for it to be useful to us, crude oil is broken down in oil refineries into its component parts, known as fractions, and these can then be used for many different purposes.

Fractions that are produced by the distillationdistillation: Distillation is when we make a liquid evaporate and then condense the vapour back to a purer liquid. of crude oil can go through a process called cracking. This chemical reaction produces smaller hydrocarbons, including alkanes and alkenes. Ethene and other alkenes are unsaturated [unsaturated: An unsaturated compound contains at least one double or triple bond. ] hydrocarbons and can be used to make polymers. Ethene can be used to make ethanol.

Cracking

Fuels made from oil mixtures containing large hydrocarbonhydrocarbons: Hydrocarbons are a group of compounds which contain the elements hydrogen and carbon. molecules are not efficient. They do not flow easily and are difficult to ignite. Crude oil often contains too many large hydrocarbon molecules and not enough small hydrocarbon molecules to meet demand - this is where cracking comes in.

Cracking allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules. Fractions containing large hydrocarbon molecules are vaporised and passed over a hot catalystcatalyst: A catalyst changes the rate of a chemical reaction without being changed by the reaction itself.. This breaks chemical bonds in the molecules, and forms smaller hydrocarbon molecules.

Cracking is an example of a thermal decomposition [thermal decomposition : A reaction in which substances are broken down by heat. ] reaction.

Some of the smaller molecules formed by cracking are used as fuels, and some of them are used to make polymerspolymers: Polymers are large molecules formed from many identical smaller molecules (monomers). in plastics manufacture.

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