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Chemiluminescence: The Chemistry of Light

6 minutes

(Describer) A machine burns lines into wood, drawing rectangles that form the letters MIT. They turn into a red and grey logo. Title: Massachusetts Institute of Technology.

[whirring]

(Describer) In darkness, two people dress as stick figures made with glowsticks.

Okay, what's the first dance move? Uh... This way, then this way? Okay.

(Describer) Title: Chemiluminescence: The Chemistry of Light. The two figures dance.

[rock music]

(female) No party is complete without everyone'sc favorite party favor... But have you ever wondered how these little tubes can produce so much light? It's all because of a little bit of chemistry called...

[crickets chirping]

(Describer) They stop.

Huh? Chemi-- chemi-- Chemilum-- Chemiluma-- Chemilumaleshence? No, no. It's chemiluminescence. Oh!

(Describer) The figures dance again. In a hallway...

The first part, chemi, comes from "chemistry,"

and the second part, luminescence, means "light." So together, chemiluminescence means light caused by chemistry. One example of chemiluminescence is the glowstick. They're so popular nowadays. You can find them pretty much anywhere.

(Describer) He opens a drawer and finds dozens of them.

Whoa!

(Describer) Outside, he trips over one.

What the--

(Describer) Back in the dark...

(female) No more funny business. Let's see how these glowsticks work.

(Describer) Dressed as a ninja in black, the man sneaks into a room and chops the air with his hands, then picks up a glowstick and chops it, making it glow.

Hai-yah! Or you can just do this.

(Describer) She bends one.

[cracking]

(Describer) Then she shakes it as it glows.

As you can see, a bright light is produced. You might think that when you crack a glowstick, you're turning on a switch, or there's a battery inside, but a glowstick produces this light because two chemicals are combining together. Two chemicals are mixed together inside the glowstick to temporarily emit a chemiluminescent light. Let's take a look inside.

(Describer) In a diagram...

A glowstick has two parts-- the outer plastic shell, which we can see, and an inner glass tube, which you might have not known was there.

In the outer layer is a chemical called cyalume. Inside the glass tube is a chemical called hydrogen peroxide and a fluorescent dye that gives a glowstick its color. When we bend a glowstick, we hear a cracking sound. This is because the inner glass breaks. The hydrogen peroxide inside the glass tube flows out and mixes with the cyalume. The mixing of these chemicals causes a chemical reaction, and they produce light. However, the chemiluminescent light cannot last forever. Once the reaction reaches completion, the glowstick will stop glowing. This is why when glowsticks are made, the different chemicals are kept separate.

(Describer) The figures dance.

(male) Because they're so lightweight, inexpensive, waterproof, and produce little heat, glowsticks are useful for many different applications, such as diving, police, and military operations.

(female) Whew! All right!

(Describer) They take off their figure heads.

Let's go to lab now to run some experiments. Welcome to lab. Before we start, let's be sure to wear our safety glasses.

(Describer) They put them on.

Ready to go! In these two cups, we have hydrogen peroxide and a fluorescent dye, typically found in a glass vial in a glowstick. In these cups, we have the chemical cyalume, which is in between the glass vial and the outside plastic of a glowstick. Let's mix it up. Let me get the lights real quick.

(Describer) As she turns off the lights to dim the room, he pairs up the glasses of cylume with the dyed hydrogen peroxide.

All right. Let's do this. All right.

(Describer) They each pick up a pair of glasses, and pour the cylume into the other glass. They glow.

Wow! Look at that! That's really bright. That was really cool. Yeah.

(Describer) They swirl the glowing liquid, and she pours hers from glass to another.

I'm going to mix it back in. That's a nice orange color. This is exactly what happens inside your glowstick. When you're cracking a glowstick, you're mixing two chemicals together. Okay, one more fun fact. You can make a glowstick glow brighter or dimmer by changing its temperature, which will speed up or slow the reaction inside the glowstick. If you put a glowstick in hot water, it'll get brighter, but won't last as long. In cold water, it'll be dimmer, but last longer. Here, I'll show you. Let's put some glowsticks in and see how they look after a few minutes.

(Describer) One is put in hot water, and one in cold. Title: Five minutes later...

Let me dim the lights to see it better.

(Describer) He dims them.

The one in hot water gets brighter than the one in cold water. Today we learned that combining two chemicals can produce light. This is called chemiluminescence.

(Describer) In darkness, glow sticks form the words “glow sticks”.

[rock music]

Hai-yah!

(Describer) Title: Filmed and Produced by Annie Tang and Grant Iwamoto. Accessibility provided by the U.S. Department of Education.

Accessibility provided by the U.S. Department of Education.

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What makes a glow stick glow? And why doesn't it heat up from the light? The answer lies in the processes taking place during chemiluminescence.

Media Details

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