The Gatorade and drain cleaner color change chemistry demonstration is a variant of the classic blue bottle demo. You can customize the demo to get a range of colors. The best part is you don’t need access to a chemistry lab for the materials, so this is a great project for teachers, parents, and home schooling.
Materials
For this project, I used:
- Gatorade containing Blue #1 (Fierce Grape or Cool Blue)
- Lye drain cleaner (purchased from Home Depot or Amazon)
- 2 Glasses
- Bamboo skewers as stirring rods (optional)
There are three requirements for this color change chem demo: a product containing FD&C Blue #1, a sugar, and a strong base. FD&C Blue #1 is a synthetic organic colorant that is also known as Blue 1, Brilliant Blue FCF, or erioglaucine. The carbohydrate can be sucrose (table sugar), dextrose, high-fructose corn syrup, etc. Two common strong bases are sodium hydroxide or lye (NaOH) and potassium hydroxide (KOH).
There is nothing magical about the product choices. Choose a drain cleaner that states it is pure or nearly pure lye or else get sodium hydroxide or potassium hydroxide. Visit the grocery store and check labels and you’ll find many products that contain Blue #1. Other sports drinks, blue freezer pops, and blue Jolly Rancher candies are great choices. If you choose a solid, dissolve it in water. If the product is sugar-free, dissolve some sugar in the liquid. Customize the color change by looking at other dyes in the product. Cool Blue Gatorade goes from a bright blue to green to colorless liquid. The Fierce Grape went from a purple-blue to yellow color.
What You Do
You can make this as simple or complicated as you like. I went with simple:
- Fill two glasses most of the way full of Gatorade (or whatever you’re using). You only need one glass, but it’s nice to see the color comparison.
- Pour in some drain cleaner. You can let it dissolve on its own, which can produce some nice color changes as diffusion works its magic. For a quick reaction, stir the liquid to dissolve the base. Strong bases react with metal, so use a bamboo skewer, a glass stirring rod, or a wooden spoon (that you don’t plan to use for food again).
- Depending on the concentration of the ingredients, you may be able to get the colors to oscillate by blowing into the liquid with a straw or simply waiting long enough. However, it’s likely you have an excess of base and the color change will remain permanent.
Now, if you want to do the math and improve your chances of a reversible or clock reaction, take note of the grams of sugar in the drink. Try to measure an equal amount of base. If you have access to a digital scale that reads small values, great. If not: For reference, a one-cent coin weighs between 2.5 and 3.1 grams. If there are 30 grams of sugar in the drink, then you want an amount of drain cleaner that weighs about as much as 10 pennies.
The temperature affects the rate of reaction. So does the concentration of the ingredients. The color changes you get might not be what you expect. For example, a product containing Blue #1 and a green dye will usually turn yellow because the green might also contain Blue #1. A product containing Blue #1 and Red #40 might be red or might be orange. Feel free to mix dyed drinks to see what you get (and please post your results in the comments).
Safety First!
Please read and heed the warnings on the container of drain cleaner or lye! It’s a good idea to wear disposable gloves to avoid skin contact with the base, but if you do touch the granules, thoroughly rinse off the residue. It’s a good idea to wear protective glasses, too. Do not drink the resulting solution! If it splashes, clean the affected skin or area with lots of water. When you’re done, you can pour the mixture down the drain (and clean the drain at the same time). If you’re worried about the remaining base, you can react it with a weak acid, like vinegar (an exothermic reaction, so expect heat).
How It Works
This demonstration, the Blue Bottle reaction, the Vanishing Valentine, and the Water into Wine demo are all examples of color-change redox reactions. They are used to raise interest in chemistry and teach redox reactions and chemical kinetics. The actual reaction mechanisms can be complex, but the premise is that the redox dye is colored in one state (usually when oxidized) and colorless or a different color in another state (usually when reduced). The color change can be set up as a clock reaction. Changing the temperature of the reaction or playing with the concentration of the reactants also affects the reaction. So, even if students don’t understand the specifics of the reaction, they can predict what will happen if temperature is increased/decreased, or the amount of starting materials is changed. It’s an excellent demonstration for a discussion of the scientific method.
References
- Campbell, Dean J.; Staiger, Felicia A.; Peterson, Joshua P. (2015). “Variations on the “Blue-Bottle” Demonstration Using Food Items That Contain FD&C Blue #1″. Journal of Chemical Education. 92 (10): 1684–1686. doi:10.1021/acs.jchemed.5b00190
- Cook, A. Gilbert; Tolliver, Randi M.; Williams, Janelle E. (1994). “The Blue Bottle Experiment Revisited: How Blue? How Sweet?”. Journal of Chemical Education. 71 (2): 160. doi:10.1021/ed071p160
- Engerer, Steven C.; Cook, A. Gilbert (1999). “The Blue Bottle Reaction as a General Chemistry Experiment on Reaction Mechanisms”. Journal of Chemical Education. 76 (11): 1519–1520. doi:10.1021/ed076p1519
- Limpanuparb, Taweetham; Areekul, Cherprang; Montriwat, Punchalee; Rajchakit, Urawadee (2017). “Blue Bottle Experiment: Learning Chemistry without Knowing the Chemicals”. Journal of Chemical Education. 94 (6): 730. doi:10.1021/acs.jchemed.6b00844