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Creating Light with Luminol Mark as Favorite (3 Favorites)

DEMONSTRATION in Chemical Change. Last updated May 04, 2022.

Summary

In this demonstration, students will observe a chemical reaction that releases energy in the form of light, demonstrating chemiluminescence.

Grade Level

High School

NGSS Alignment

This demonstration will help prepare your students to meet the performance expectations in the following standards:

  • MS-PS1-2: Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
  • HS-PS1-2: Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.
  • Scientific and Engineering Practices:
    • Constructing Explanations and Designing Solutions

Objectives

By the end of this demonstration, students should be able to:

  • Understand that light is a form of energy.
  • Explain that some chemical reactions release energy in the form of light, known as chemiluminescence.
  • Describe several real-world examples of chemiluminescence.

Chemistry Topics

This demonstration supports students’ understanding of:

  • Chemical Reactions
  • Chemiluminescence
  • Chemical Change
  • Energy
  • Light
Creating Light with Luminol

Time

Teacher Preparation: 10 minutes
Lesson: 10 minutes

Materials

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Gloves should be worn when handling the chemicals used in this demonstration.
  • Wash your hands thoroughly before leaving the lab.
  • Students should wear proper safety gear during chemistry demonstrations. Safety goggles and a lab apron are required.
  • Review each chemical's safety considerations and hazards through the related SDS linked in the Materials section.
  • Hydrogen peroxide (H2O2) is a mild oxidant, care should be taken while handling it.
  • Spills should be avoided but can be cleaned up with water and paper towels or a spill pad.

Teacher Notes

  • For more information about this demonstration and others like it, see the article, The Wonderful world of Chemistry: A Magic Show, published in the May 2022 issue of Chemistry Solutions.
  • A video recording of this demonstration as part of an outreach event can be viewed at the 40:32 timestamp in the Magic Show video.
  • The reaction works best when solutions are prepared and used fresh.
  • The demonstration should be performed in the dark for the best effect.
  • Procedure:
    • Create Solution 1: Dissolve the luminol and salts in deionized water to a final volume of 1L.
    • Create Solution 2: Dilute hydrogen peroxide (H2O2) in deionized water to a final volume of 1L.
    • Pour both solutions slowly and simultaneously into a large beaker or Erlenmeyer flask. Once the solutions are combined, it should continue to glow for a few minutes.
  • The visual effects can be enhanced by pouring the solutions down a spiral tube of glass or Tygon tubing (see photo and/or video).
  • In a large number of chemical reactions, energy is released in the form of heat. This is why we burn natural gas to heat our houses in winter. A smaller, but important, class of reactions releases energy in the form of light. In this demonstration, a chemical reaction occurs between Luminol and hydrogen peroxide (it is catalyzed by Cu2+ ions). Light is released as the product forms, which is what the audience sees when the two solutions mix.
  • The chemical equation for the reaction is shown below:
  • Classroom discussion could include topics such as:
    • Some species of jellyfish and other deep-sea organisms that survive mostly in the dark display chemiluminescence. Essentially a chemical reaction occurs in the organism that releases light. Organisms typically release light either as a defense mechanism to ward off predators or to attract prey. Depending on the exact chemical reaction that occurs different colors are emitted, as the color of the light is directly related to the structure of the fluorescent molecule.
    • Chemiluminescence is used in forensic analysis of a crime scene to detect the presence of blood. Specifically, iron in blood triggers the reaction of Luminol with hydrogen peroxide, which causes bloodstains to glow.
    • Chemiluminescence involves a similar concept to flame tests of metal ions, where species in an excited state release energy in the form of light. In the flame tests metal ion are excited using heat, whereas in the Luminol demonstration heat generated during the reaction causes the fluorescent molecule to be in an excited state.
  • Additional Teaching Resource ideas related to this topic: