4.28: Describe How Bromine Water can be Used to Distinguish Between an Alkane and an Alkene

ALKANES: Homologous series of hydrocarbon compounds containing only single Carbon bonds - has the general formula CnH2n+2

ALKENES: Homologous series of hydrocarbon compounds containing double Carbon bonds - has the general formula CnH2n

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USE OF BROMINE WATER TO DISTINGUISH ALKANE AND ALKENE

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Presence of double bond (C=C) allows Alkenes to react in ways that Alkanes cannot, therefore allowing Alkenes and Alkanes to be identified using chemical test:

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TEST TO DISTINGUISH ALKANE AND ALKENE

Diagram showing the Result of the Test using Bromine Water with Alkanes and Alkenes

EXPLANATION: Bromine Water is an orange solution of Bromine When Bromine Water is shaken with an Alkane, it will remain as an orange solution as Alkanes are saturated (does not have double Carbon bonds) so are hence unreactive However, when Bromine Water is shaken with an Alkene, it will decolourise into a colourless solution as Alkenes are unsaturated (has double carbon bonds) so will hence react with Bromine atoms - addition reaction