Click a thumbnail picture below to view a larger version.

View Movie

Narrative
Three test tubes contain bromine. Benzene is added to the first tube, phenol to the second, and toluene to the third tube. The red color of the bromine vapor disappears from the second tube containing the phenol. pH paper indicates that hydrogen bromide was produced in this reaction.

Discussion
Bromine is shown in each of three test tubes. Benzene is added to the first tube, phenol to the second, and toluene to the third tube. The red color of the bromine vapor disappears from the second tube containing the phenol. When the vapor in this tube is tested with pH paper, the red color indicates the presence of an acidic gas (hydrogen bromide). Benzene and toluene do not react with bromine in the absence of a catalyst. Phenol is more reactive due to the presence of an electron donating hydroxyl group and reacts with bromine by a substitution reaction forming hydrogen bromide gas.