CHED 71 |
| This colorful experiment allows middle school students to develop the concept of the co-solvent. The experiment is also an excellent demonstration for both school and university students. Students use the ‘like dissolves like' concept and the color patterns of electrostatic potential maps to explain why the blue pigment guaiazulene dissolves in hexane, but not in water, whereas FD&C dye, Yellow #5, dissolves in water, but not in hexane. Next, they are supplied a list of possible solvents and use molecular modeling to select the one most likely to dissolve both hexane and water. When they carry out the experiment, they discover that blue and yellow layers of the pigments dissolve in the acetone co-solvent to form a green solution. Finally, they learn about the salting out process, by adding aqueous sodium or potassium chloride to the solution, which causes the blue and yellow layers to be gradually regenerated. |
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General Posters
7:30 PM-9:30 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Chemical Education |