An undergraduate summer research student in an organic chemistry laboratory synthesized cyclohexene from cyclohexanol. She wanted to test whether she formed the alkene, but much to her disappointment found that the NMR, IR, and mass spectrometers were unavailable due to repairs. All she needs to do is ascertain whether she formed the alkene or not. Suggest to her a visual functional test that she can use to detect the presence of an alkene. Explain why it is specific for alkenes in this situation.