Test tubes a and b initially have brown color solution known as bromine water. on passing methane in test tube a, there is no change whereas on passing ethene in test tube b decolorization of bromine water takes place. Account for the decolorization of bromine water in test tube B
Answers
Uses of the test :
It helps in identifying saturation .
It helps in distinguishing compounds.
It helps in study of organic compounds.
Bromine solution test
If this mixture is added to an unsaturated compounds such as alkenes or alkanes then :
- Bromine water is brown
- The supernatant liquid gets decolourised.
However saturated compounds do not respond to the above test.
In order to test unsaturation first add bromine solution
If the reagnant decolorises from brown to colourless then the compound is unsaturated
Otherwise if the reaction does not occur , then it is a saturated compound.
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Answer:
ethene + bromine ------------> bromoethane + hydrogen
reaction is addition reaction..
Bromine gets mixed and bonded with ethene to form bromoethane as ethene is unsaturated and can add some more atoms.So the reddish brown colour of bromine is not seen in B.
In A this doesn't happen as methane is saturated and hence can't add some more atoms . So the reddish colour can be seen.
This is called bromine water test for unsaturation as we can find out whether the compound is saturated or unsaturated by means of bromine water.