Alkenes can be shown to be unsaturated using bromine water.Describe the colour change that occur when an alkene react with bromine water.Please explain in this question what the term unsaturated...

Alkenes can be shown to be unsaturated using bromine water.Describe the colour change that occur when an alkene react with bromine water.

Please explain in this question what the term unsaturated means because i hav a difficulty in understanding the terms unsaturated and saturated. (this is a question from the IGCSE 2009 paper).

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doabbott3 | College Teacher | (Level 1) Adjunct Educator

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An unsaturated Hydrocarbon (alkene) has at least one double bonded c=c. Saturated it becomes c-c. No double bonds are allowed in a "saturated" hydrocarbon.  Bromine water (reddish brown), contains Br2. Br2 actively attacks a c=c bond forming a c-c bond destroying the reddish brown Br2 and turning the Br2 water solutioncolorless. The fact that there IS a color change would mean double bonds are present; and the sample is an Alkene. No color change, with Bromine water, would indicate an Alkane present.

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