SNC2D/2P Chemical Reactions; Light and Geometric Optics/Chemical
Reactions and their Practical Applications
Teacher Demo: Chemiluminescence
Topics
Timing
evidence of chemical reactions or types of light preparation: 10 min
emissions
demonstration: 10–15 min
Specific Expectations
SNC2D
A1.10 draw conclusions based on inquiry results and research findings, and justify their
conclusions
C3.3 describe the types of evidence that indicate chemical change (e.g., changes in colour, the
production of a gas, the formation of a precipitate, the production or absorption of heat, the
production of light)
E3.1 describe and explain various types of light emissions (e.g., chemiluminescence,
bioluminescence, incandescence, fluorescence, phosphorescence, triboluminescence; from an
electric discharge or light-emitting diode [LED])
SNC2P
A1.10 draw conclusions based on inquiry results and research findings, and justify their
conclusions
E3.1 describe various types of light emissions (e.g., chemiluminescence, bioluminescence,
incandescence, electric discharge) and how they produce light
Introduction
This demonstration is definitely an eye-catching crowd-pleaser. It is a great demonstration to
show the interconnection between physics and chemistry, linking an example of light emission to
evidence of chemical reactions. It is similar to a common example of bioluminescence, which
occurs in fireflies, allowing them to “glow” in the dark.
Materials
chemical safety goggles
lab coat or apron
protective gloves
0.05 g luminol
100 mL 1.0 mol/L sodium hydroxide solution,
NaOH(aq)
10 mL bleach
90 mL distilled water
ice bath
electronic balance (± 0.01 g)
100 mL graduated cylinder
two 250 mL beakers
round-bottomed flask or Erlenmeyer flask (at
least 400 mL)
Safety Considerations




Provide MSDS sheets for all chemicals used.
Sodium hydroxide and bleach are corrosive and toxic. Avoid skin or eye contact. Safety
goggles, protective gloves, and a lab coat or apron should be worn when handling these
solutions. Wash your hands and flush your eyes immediately if you come into contact with
either substance.
Luminol is a combustible solid. Keep it away from any heat sources and open flames.
Luminol is slightly toxic by ingestion. If ingested do not induce vomiting and call poison
control immediately. If luminol comes into contact with your eyes, flush them immediately
with water or eye-wash fluid.
Hazardous Materials Identification System Rating
(0-minimal 1-slight 2-moderate 3-serious 4-severe)
1.0 mol/L sodium hydroxide
luminol
solution
commercial bleach (5%
NaClO(aq))
Procedure
Wear appropriate PPE: chemical safety goggles, lab coat or apron, protective gloves.
For best results, prepare the following solutions at least 15 min before performing the
demonstration.
1.
Prepare an ice bath large enough for two 250 mL beakers.
2.
In the first beaker, dissolve 0.05 g luminol in 100 mL of 1.0 mol/L sodium hydroxide
solution, NaOH(aq).
3.
In the second beaker, prepare a 0.5 % sodium hypochlorite solution, NaClO(aq), by adding
10 mL of commercial bleach to approximately 90 mL distilled water.
4.
Place both solutions in the ice bath until chilled (15–30 min).
During class:
5.
Turn off the lights for dramatic effect.
6.
Observe
Instruct students to watch carefully as you slowly pour the two solutions in the roundbottomed or Erlenmeyer flask. Swirl to mix the solutions.
7.
Explain
Have students explain what they observed.
Disposal
Add vinegar to neutralize the final mixture prior to disposal. Follow disposal procedures that are
consistent with school board protocol and appropriate for your municipality.
What happens?
When the solutions are mixed, a blue glow will result. The solution will be a yellow/green colour
when the lights are turned back on.
How does it work?
Luminol (2-aminophthalhydrazide) is an organic compound that is colourless and unremarkable
in a neutral or acidic solutions, but emits bright blue light when it undergoes oxidation under
basic conditions. This is an example of a chemiluminescent reaction, which is a reaction which
produces light (and usually a small amount of heat). The simplified chemical equation below
does not include all of the steps in this reaction, one of which involves oxygen, to produce the
anion shown below.
colourless
yellow/green; blue light emitted
Teaching Suggestions/Hints
1.
2.
Prepare the solutions 15 min prior to performing the demonstration. For added dramatic
effect, you could pour both solutions simultaneously into a glass or plastic spiral tube down
into a beaker or flask.
Hydrogen peroxide solution, H2O2(aq) and potassium ferricyanide, K3[Fe(CN)6], can be
used instead of bleach. See additional resources for link to instructions.
Next Steps
Students could investigate chemical reactions that produce other forms of energy such as
electricity as well as heat and light.
Students could research bioluminescence and how it is used by some bacteria, phytoplankton,
and animals.
Additional Resources
1.
2.
3.
Video of demonstration performed very creatively:
http://www.mindbites.com/lesson/4875-chemistry-demo-luminol
Detailed instructions of the chemistry of the reaction as well as demonstration instructions
using hydrogen peroxide and potassium ferricyanide instead of bleach:
http://www.carolina.com/category/teacher+resources/classroom+activities/luminol+the+gl
owing+reaction.do
Chemical reaction retrieved from:
http://ncsu.edu/project/chemistrydemos/Light/Luminol.pdf