Chemistry demonstrations in which solutions appear to magically change color leave a lasting impression on students and help instill an interest in science. Here's a color change demo in which a solution seems to change from water to wine to milk to beer simply be being poured into the appropriate beverage glass.
Time Required: Prepare the solutions in advance; demo time is up to you
- First, prepare the glassware, since this demonstration relies on the presence of chemicals added to the glasses before the 'water' is added.
- For the 'water' glass: Fill the glass about 3/4 full of distilled water. Add 20-25 ml of saturated sodium bicarbonate with 20% sodium carbonate solution. The solution should have a pH = 9.
- Place a few drops of phenolphthalein indicator in the bottom of the wine glass.
- Pour ~10 ml saturated barium chloride solution into the bottom of the milk glass.
- Place a very small number of crystals of sodium dichromate into the beer mug. Up to this point, the set-up can be performed in advance of the demonstration. Just prior to performing the demo, add 5 ml concentrated HCl to the beer mug.
- To perform the demonstration, simply pour the solution from the water glass into the wine glass. Pour the resulting solution into the milk glass. This solution is finally poured into the beer mug.
- Use goggles, gloves, and proper safety precautions when making the solutions and handling the chemicals. In particular, use caution with the conc. HCl, which can cause a serious acid burn.
- Avoid accidents! If you are using real drinking glasses, please reserve this glassware solely for this demonstration and take care that the prepared glassware is kept away from children/pets/etc. As always, label your glassware, too.
What You Need:
- distilled water
- saturated sodium bicarbonate; 20% sodium carbonate ph=9
- phenolphthalein indicator
- saturated barium chloride solution (aqueous)
- crystals of sodium dichromate
- concentrated hydrochloric acid
- water glass
- wine glass
- milk glass
- beer mug