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Thursday, March 16, 2006

The Chemistry Behind Lightsticks




Almost everyone has seen a lightstick. A lightstick is a plastic tube with a glass vile inside it. When the tube is bent, the vial breaks allowing the chemicals to mix and react. The colorfully glowing sticks utilize a chemical process called chemiluminescence where energy is released in the form of light. The most common lightsticks use chemiluminescence with colored tubes to provide the desired color.
This process is not caused by heat and may not produce heat, but the speed of reaction is still dependence on environmental heat. The colder the environment, the slower the reaction and will glow longer.
Lightsticks have three parts. There are two chemicals that react to release energy which is converted to light. Usually, commercial lightsticks utilize the reaction between hydrogen peroxide and acetonitrile. When the glass vile is broken and the two chemicals are mixed, it will release enough energy to excite the electrons in the oxygen to cause the electrons to jump to a higher energy level and then fall back releasing light.
Specifically, the hydrogen peroxide oxidizes the acetonitril eventually forming excited oxygen. This decomposes and releases the energy as light as can be seen stepwise above.
More on chemiluminescence can be found here on “A Chemiluminescence Reaction between Hydrogen Peroxide and Acetonitrile and Its Applications.”

7 Comments:

  • 7/10 - These are not the chemicals used in glowsticks. Glowsticks rely on a much stronger chemiluminescent reaction. Acetonitrile has a triple bond, not double as it appears in your diagram. Also some arrows are missing in the mechanism. The last step should show conversion of singlet oxygen to the triplet ground state. This looks like a mistake in the original paper.

    By Blogger Jean-Claude Bradley, at 5:37 AM  

  • This is actually a great chemistry demonstration for little kids. We designed a a little system that once you open that stopcock, mixes the acetonitrile and peroxide in a "twisty tube", so the kids can see it light up and move thru the funnel.

    By Anonymous Organic Chemistry, at 9:53 AM  

  • I just found your blog, looking through google. looks interesting. I've never seen a chemiluminescence reaction mechanism

    By Blogger Felix, at 12:30 PM  

  • fascinating stuff. i had just bought some glow sticks the other day and i was wondering what made them tick. thanks for the explanation!

    By Blogger Phil, at 12:40 PM  

  • hoew can i do a chemsitry investigation related to glow sticks that involves titrations and colorimetry?

    By Anonymous Anonymous, at 3:59 PM  

  • Hi,

    Popular ways that Glow sticks are used are as glow bracelets and glow necklaces. Used as body lights, these are inexpensive additions to attract attention at any social gathering. The added flare of cool flashing broaches and neon colored necklaces will give your party the edge in design and uniqueness.

    Thanks
    http://www.glow-sticks.org

    By Anonymous Anonymous, at 6:19 AM  

  • These light sticks use vials not "viles".

    By Anonymous Anonymous, at 5:35 PM  

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