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What are the Uses of Alkanes and Alkenes?

Alkanes are unreactive and are mainly used as fuels.

Alkenes are much more reactive than alkanes
because alkenes are unsaturated
(they have a reactive double bond).

Alkenes are the starting material for many different chemicals.
They are extremely useful to the chemical industry.
Ethene and propene are the starting materials for polymers,
giving poly(ethene) and poly(propene) - see polymers.

How to Tell an Alkane from an Alkene?

An alkene may be distinguished from an alkane by
shaking the hydrocarbon with bromine water.
Bromine water is brown or orange, and will lose its colour
when it reacts with the double bond of an alkene.
Bromine water will stay brown with an alkane
because an alkane has no double bonds.

Bromine adds across the double bond of an alkene
to form a colourless dibromo alkane.
This is an example of an addition reaction.

What is an Addition Reaction?

An addition reaction occurs when two or more reactants
join together to form a single product.
Other examples of addition reactions are
the hydrogenation of vegetable oils,
addition polymerisation and the hydration of ethene.

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