Get ready to turn out the lights and watch as two solutions are poured together to produce a glow-in-the-dark blue light that lasts for several seconds.
luminol, 0.23 grams
sodium hydroxide solution, 500 ml of a 0.10 M NaOH solution
dilute bleach solution, 40 ml of laundry bleach in 400 ml of distilled water
beaker or clear glass cup
ice bath
1. Make the luminol solution by dissolving 0.23 grams of luminol in 500 ml of the 0.10 M sodium hydroxide solution.
2. Make the bleach solution by combining 40 ml of household laundry bleach with 400 ml of distilled water.
3. Chill the solutions in an ice water bath. Do not let them freeze.
4. Turn out the lights.
5. At the same time, pour about 100 ml of each solution into the beaker.
6.Observe the glowing blue color.
Luminescence is light without heat. This reaction involves chemiluminescence, which is the production of cold light by a chemical reaction. Chemical energy is converted into light.
Another kind of luminescence is bioluminescence, the production of cold light by living organisms. A good example is a lightning bug. Other examples include some fish, mushrooms, and fungi.
Fluorescence and phosphorescence are other kinds of luminescence. You can discuss any or all of these types, have students do research, and extend this discussion as much as you like.
1. The colder the solutions, the longer the glowing color lasts. It would be interesting to ask your students why this happens. The colder the solutions, the slower the reaction. The molecules move slower and do not have as much energy as they would at a higher temperature.
2. You might want to pour the solutions into a funnel connected to a coiled plastic tube which empties into the beaker. The glow can be seen as the solutions go through the coil.
3. The sodium hydroxide is corrosive and can burn your skin and eyes. Wear safety goggles.
The solution may be rinsed down the drain with plenty of water.