Write a test to detect the presence of double bond in a molecule.
There are two tests to detect the presence of unsaturated double bond in an organic molecule, the bromine water test and Bayer’s test.
In the bromine water test, when the molecule is added to bromine water, bromine is added to the carbon atoms across the double bond. The orange-brown colour of bromine water changes and becomes colourless at the end of the reaction.
In Bayer’s test, alkaline KMnO4 is used to detect unsaturated carbon with double bond. The chemical gives rise to [O], which hydrolyses the carbons across double bond, and the solution containing the two compounds goes from purple colour to colourless.
2KMnO4 + H2O → 2KOH + 2MnO2 + 3[O]
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