bp's science: the color of fireworks (v.1)

Oliver and I watch fireworks over the Potomac, 2010

So how was the fireworks show you saw last night? Because we live in a tall building, we went to the roof (our celebration was low-key this year) and got to enjoy at least 9 different firework shows, including the one downtown. We could see the Washington Memorial all lit up, it was fantastic really.

So what gives fireworks their color? The answer is metal salts. In chemistry terms, salts are compounds created from the reaction of an acid and a base (table salt is sodium (Na from a base), chloride (Cl from an acid), NaCl). Different salts give off different colors. See the chart I found here below.

Color Compound
Red strontium salts, lithium salts
lithium carbonate, Li2CO3 = red
strontium carbonate, SrCO3 = bright red
Orange calcium salts
calcium chloride, CaCl2
calcium sulfate, CaSO4·xH2O, where x = 0,2,3,5
Gold incandescence of iron (with carbon), charcoal, or lampblack
Yellow sodium compounds
sodium nitrate, NaNO3
cryolite, Na3AlF6
Electric White white-hot metal, such as magnesium or aluminum
barium oxide, BaO
Green barium compounds + chlorine producer
barium chloride, BaCl+ = bright green
Blue copper compounds + chlorine producer
copper acetoarsenite (Paris Green), Cu3As2O3Cu(C2H3O2)2 = blue
copper (I) chloride, CuCl = turquoise blue
Purple mixture of strontium (red) and copper (blue) compounds
Silver burning aluminum, titanium, or magnesium powder or flakes

So there you have it, the presence of barium makes green, copper makes blue, strontium makes red. And when you mix copper and strontium salts together, you've got purple. Pretty cool.

And if you didn't get your firework fix from yesterday, take a look at this interesting NOVA video concerning the color of fireworks. It's interesting stuff.


kel said...

being the color nerd that i am, i loved this post. i really liked seeing the different compounds. it felt like science.

jo said...

So, so cool. I'm so glad you posted this, because I was wondering about this very thing. I can only seem to remember that magnesium burns white, and then I forget the rest. Thanks, my chemistry go-to gal.