Bromine water test is used to differentiate between the unsaturated compounds (like alkenes and alkynes) and the saturated compounds. For this purpose, bromine is used in the form of bromine water. A solution of bromine in water is called bromine water. Bromine water has a red-brown color due to the presence of bromine in it. When bromine water is added to an unsaturated compound, then bromine gets added to the unsaturated compound and the red-brown color of bromine water is discharged. So, if an organic compound decolorizes bromine water, then it will be an unsaturated hydrocarbon (containing a double bond or a triple bond), but saturated hydrocarbon (alkanes) do not decolorize bromine water.
Bromine water test is perform to differentiate between the unsaturated compounds (like alkenes and alkynes) and the saturated compounds. Bromine water is added to an un-saturated hydrocarbon red brown color of bromine solution is discharged. Si if there is dis-coloration then the compound will be an unsaturated Hydrocarbon.