Magicians and chemistry teachers know how to turn water into wine or blood. Of course, this is simply a chemical reaction that causes a clear liquid to turn pink or red. If the conditions are right, the color shifts back and forth. The water into wine demonstration is the easiest color change chemistry demonstration to perform.
You only need a few basic chemicals and materials for this project:
- Phenolphthalein pH indicator
- Sodium carbonate
- Two glasses
- A drinking straw or pipette
Phenolphthalein is one of the most common pH indicators. Most school labs keep it on hand or else anyone can purchase it online. It’s also the key ingredient in disappearing ink. Sodium carbonate is the chemical name of washing soda. Again, it’s readily available as a lab chemical, may be sold as a laundry soap, or can be ordered online. You can also make it yourself from baking soda. It doesn’t matter whether you use glass or plastic dishes for this project. Using wine glasses is a nice touch!
Perform the Demonstration
Prepare the glasses in advance of the demonstration.
- Sprinkle a bit of sodium carbonate in the bottom of the first glass. The proportion of sodium carbonate to indicator is not critical to get the color change, but if you want the colors to cycle between clear and red, a ratio of five parts sodium carbonate to 10 drops phenolphthalein solution is ideal.
- Fill the second glass halfway full of water and add 10 drops of phenolphthalein solution.
- When you’re ready to perform the demonstration, simply pour the liquid from the second glass into the empty-looking first glass. Swirl around the liquid to dissolve the sodium carbonate and watch the contents change from clear to red.
- To change the “wine” or “blood” back into “water,” blow air into the red liquid. This changes its pH and decolorizes the dye. Over time, the contents of the glass will return to their red color. You can repeat the color change as many times as you like.
- Another option is to use a third glass, which contains a few drops of a concentrated acid (e.g., muriatic or hydrochloric acid). The acid neutralizes the base and returns the solution to its colorless state. Once neutralized, the liquid color won’t change to red unless more sodium carbonate (or another base) is introduced.
How It Works
The water into wine or blood demonstration often accompanies lectures on pH, acid-base indicators, and color chemistry. The reaction is intriguing, so it helps raise student interest in science.
Phenolphthalein is a great pH indicator for acid-base titrations, plus it’s a component of universal indicator. In this demonstration, the indicator changes from colorless at a neutral pH to pink/red under basic conditions. Water is made basic or more alkaline by adding sodium carbonate, which is a weak base. When you blow “air” into the liquid, you’re adding carbon dioxide from your lungs. This forms carbonic acid in the liquid and neutralizes the sodium carbonate.
While only two states are used in this demonstration, phenolphthalein can adopt four states in aqueous solution. Under strongly acidic conditions, it turns orange (H3In+). Between pH 0 and 8.2, it is colorless (H2In). Between pH 8.2 and 10.0 it is pink to fuchsia (In2−), and under strongly alkaline conditions (pH>10.0), it is colorless (In(OH)3−).
When you are finished with the demonstration, you can pour the contents down the drain. Do not drink the liquid. Phenolphthalein is a laxative. It was commonly sold for this purpose, but is being removed from products because of concerns of health effects.
- Dunnick, J. K.; Hailey, J. R. (1996). “Phenolphthalein Exposure Causes Multiple Carcinogenic Effects in Experimental Model Systems“. Cancer Research. 56 (21): 4922–4926.
- Schwarzenbach, Gerold (1957). Complexometric Titrations. Translated by Irving, Harry (1st English ed.). London: Methuen & Co.
- Zumdahl, Steven S. (2009). Chemical Principles (6th ed.). New York: Houghton Mifflin Company.