How To Do the Color Change Chameleon Chemistry Demonstration

Rainbow Redox Reaction Color Change Chemistry Demo

The chemical chameleon demonstrations changes colors from purple to blue to green to orange-yellow before the solution finally turns clear.
The chemical chameleon demonstrations changes colors from purple to blue to green to orange-yellow before the solution finally turns clear. Arne Pastoor / Getty Images

The chemical chameleon is a wonderful color-change chemistry demonstration that may be used to illustrate redox reactions. The color change runs from purple to blue to green to orange-yellow and finally to clear.

Color Change Chameleon Materials

For this demonstration, you start by preparing two separate solutions:

Solution A

  • 2 mg potassium permanganate
  • 500 ml distilled water

Dissolve a small amount of potassium permanganate into water.

The amount isn't critical, but don't use too much or else the solution will be too deeply colored to see the color changes. Use distilled water rather than tap water to avoid problems caused by salts in tap water that affect water pH and can interfere with the reaction. The solution should be a deep purple color.

Solution B

  • 6 g sugar (sucrose)
  • 10 g sodium hydroxide (NaOH)
  • 750 ml distilled water

Dissolve the sugar and sodium hydroxide in the water. The reaction between sodium hydroxide and water is exothermic, so expect some heat to be produced. This will be a clear solution.

Make the Chameleon Change Colors

When you're ready to start the demonstration, all you need to do is mix the two solutions together. You'll get the most dramatic effect if you swirl the mixture together to thoroughly combine the reactants.

Upon mixing, the purple of the potassium permanganate solution immediately changes to blue.

It changes to green fairly quickly, but it takes a few minutes for the next color change to pale orange-yellow, as manganese dioxide (MnO2) precipitates. If you let the solution sit long enough, the manganese dioxide will sink to the bottom of the flask, leaving you with a clear liquid.

Chemical Chameleon Redox Reaction

The color changes are the result oxidation and reduction or a redox reaction.

The potassium permanganate is reduced (gains electrons), while the sugar is oxidized (loses electrons). This occurs in two steps. First, the permanangate ion (purple in solution) is reduced to form the manganate ion (green in solution):

MnO4- + e- → MnO42-

As the reaction is proceeding, both the purple permanganate and green manganate are present, blending together to produce a solution that appears blue. Eventually, there is more green manganate, yielding a green solution.

Next, the green manganate ion is further reduced and forms manganese dioxide:

MnO42- + 2 H2O + 2 e- → MnO2 + 4 OH-

Manganese dioxide is golden brown solid, but the particles are so small they make the solution appear to change color. Eventually, the particles will settle out of solution, leaving it clear.

The chameleon demonstration is just one of many possible color change chemistry experiments you can perform. If you don't have the materials on hand for this particular demonstration, consider trying a different one.

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Helmenstine, Anne Marie, Ph.D. "How To Do the Color Change Chameleon Chemistry Demonstration." ThoughtCo, Jun. 26, 2016, thoughtco.com/how-to-do-color-change-chameleon-4057571. Helmenstine, Anne Marie, Ph.D. (2016, June 26). How To Do the Color Change Chameleon Chemistry Demonstration. Retrieved from https://www.thoughtco.com/how-to-do-color-change-chameleon-4057571 Helmenstine, Anne Marie, Ph.D. "How To Do the Color Change Chameleon Chemistry Demonstration." ThoughtCo. https://www.thoughtco.com/how-to-do-color-change-chameleon-4057571 (accessed November 19, 2017).