This popular chemistry demonstration is often called turning water into wine or turning water into blood. It's really a simple example of a pH indicator.
Phenolphthalein, an acid-base indicator, is added to water, which is then poured into a second glass containing a base. If you get the pH of the resulting solution right, you can make the water turn from clear to red-and back to clear again-as many times as you like. The principle for this demonstration is the same as for the disappearing ink formula.
What You'll Need
- Phenolphthalein pH indicator
- Sodium carbonate
- Two drinking glasses
- Stirring rod
- Straw or pipette
Here's How to Do It
- Sprinkle sodium carbonate to coat the bottom of a drinking glass.
- Fill a second glass halfway full of water. Add ~10 drops phenolphthalein indicator solution to the water. (The glasses can be prepared in advance.)
- To change water into wine or blood, pour the water with indicator into the glass that contains the sodium carbonate. Stir the contents to mix the sodium carbonate, and watch the water change from clear to red.
- If you'd like, you can use a straw to blow air into the red liquid which will change it back to clear.
Tips for Success
- Phenolphthalein and sodium carbonate can be ordered freely from any scientific supplier. Most grade school and high school science labs have these chemicals, although you can order them yourself.
- For a normal drinking glass, the ratio used to get the reversible color change reaction is five parts sodium carbonate per 10 drops of a phenolphthalein stock solution.
- Don't drink the water/wine/blood. It isn't particularly toxic, but it isn't good for you either. Just pour the liquid down the drain when the demonstration is complete.