Most people are very familiar with glow sticks – we see them all the time around holidays like Halloween or Independence Day! Even so, glow sticks are still amazing to see in action. They create a soft light of just about any color that lasts for hours or days, and do this without producing any heat whatsoever (unlike electric light bulbs, which get super hot!). We create a glow stick reaction during our show that is super bright but doesn’t last very long, and do a neat experiment by mixing two different colors to see what happens.
Our glow stick liquids are bought straight from the manufacturer, Cyalume. These are the same people that make just about every other glow stick you come across! But for us, they made a special formula that is super-concentrated (Mua ha ha!).
The glow stick reaction is made of two parts: an oxalate solution and an activator solution. We simply mix the two together, and the liquid begins to glow! Our special formula glows extremely brightly, but only lasts for a few minutes at maximum brightness. It quickly fades to “regular glow stick levels”, and is completely dark after about 48 hours. Here it is in action:
(This video features our new brother, Gavin Science!)
Weirdly, the colors don’t mix like we expected! We think this may be because the dyes in each oxalate liquid react with each other to make a completely new color. Or maybe the red color is so strong that it overwhelms anything else you mix it with. Time for more experiments!
The Science:
Both liquids are made of rather complicated organic* chemicals, but I’ll try to simplify it as much as I can here.
The oxalate solution mainly contains a compound called diphenyl oxalate along with a dye. The dye is what gives the glow stick its color. The activator solution contains some hydrogen peroxide, H2O2, (among other things). When mixed, the peroxide reacts with the diphenyl oxalate to form an intermediate compound called a peroxyacid ester (1,2-dioxetanedione). Quite a mouthful! This molecule is unstable, and quickly decomposes into carbon dioxide (CO2) gas. This releases energy which is captured by the dye molecules and transformed into the light we see. The reaction is illustrated below (click the image for a larger version):
The carbon dioxide produced in this reaction bubbles out, and looks like carbonation from your soda (and in fact, it’s the same gas! But you wouldn’t want to drink the glowing liquid). This happens in all glow sticks, but you may not notice it in regular ones because they are a weaker formula than ours. As you can see, organic* chemistry is very complicated, but can give us some very cool results!
Disposal:
While glow stick chemicals are said to be nontoxic, they still shouldn’t just be poured down the drain. We collect all our spent glow stick liquid in a special waste container, and turn it in to our local waste control office for proper disposal at a licensed facility.
*In chemistry, “organic” means it is a chemical that has carbon atoms in it. It’s not pesticide-free!