They are used as starting materials in the syntheses of alcohols, plastics, laquers, detergents, and fuels. The most important alkenes for the chemical industry are ethene, propene and 1,3-butadiene. Ethene is the most important organic feedstock in the chemical industry.
What are alkanes and alkenes?
Hydrocarbons are compounds made from carbon and hydrogen atoms joined by covalent bonds. Alkanes are saturated - they have only single bonds. Alkenes have a double bond - they are unsaturated. Alkenes react with brown bromine water and decolourise it, but alkanes do not.
What is the test for an alkene?
Testing for alkenes. Bromine water is used to tell the difference between an alkane and an alkene. An alkene will turn brown bromine water colourless as it reacts with the double bond. Bromine water remains brown in the presence of an alkane as there is no double bond.