Posted by Jamie on Sunday, June 20, 2010 at 3:36pm.


You are given three test tubes that contain colourless liquid. One test tube contains benzene, another contains ethanol, and the third contains 2,4-hexadiene. Design a procedure that will tell you the contents of each test tube. Describe your expected observations.

So benzene is an aromatic, ethanol is an alcohol, and hexadiene is an alkene. I'm not sure where to go from here.. please help :)

Chemistry - DrBob222, Sunday, June 20, 2010 at 5:43pm
Try using this information. Ethanol dissolves in water. Does benzene? Does 2,4-hexadiene?
The diene adds Br2 to it easily. What can you do with that?

Chemistry - Jamie, Sunday, June 20, 2010 at 8:02pm
hmmmm..
well what methods should i be using?
should i add water to each of them, and i will know that the only homogenous mixture is ethanol. Then I could add Br2 to the remaining ones, and the 2,4-hexadiene will be uniform, leaving me with the benzene?
am i on the right track?

Yes, but I would clean it up a little.

To a small portion of each "unknown" in separate test tubes, add a few drops of water and shake thoroughly. The one miscible with water is the ethanol sample. To a new portion of the remaining unknowns, add a few drops of bromine water. The hexadiene will decolorize the bromine solution much more quickly than will the benzene (if at all). The remaining solution must be benzene. Something like this is the way I would write up a procedure.