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The Chemistry of Firework Displays
Ponca City, We love you writes "David Ropeik writes at MSNBC that there's a lot more to making a basic firework display than putting a fuel source and an oxidizer together. Pyrotechnic chemists, who are trying to create bedazzlement instead of bang, don't want their work to explode, but to burn for a bit, so it gives a good visual show. To achieve the desired effect, the sizes of the particles of each ingredient have to be just right, and the ingredients have to be blended together just right. To slow down the burning, chemists use big grains of chemicals, in the range of 250 to 300 microns, and they don't blend the ingredients together very well, making it harder for the fuel and oxidizer to combine and burn, thus producing a longer and brighter effect. Surprisingly few emitters are used in pyrotechnics, and there are no commercially useful emitters in blue-green to emerald green in the 490-520 nm region. Energy from the fire in the basic fuel is transferred to the atoms of the colorant chemicals, exciting the electrons in those chemicals into a higher energy state. As they cool down, they move back to a lower state of energy, emitting light. So, you actually see the colors in fireworks as they're cooling down. To get the really tricky shapes, like stars or hearts, the colorant pellets are pasted on a piece of paper in the desired pattern. That paper is put in the middle of the shell with explosive charges above it, and below. When those charges go off, they burn up the paper, and send the ignited colorant pellets out in the same pattern they were in on the sheet of paper, spreading wider apart as they fly."
It's July 4. I'm going to watch fireworks today, so Slashdot posted something about fireworks.
The USA flag on the story is a bit misleading too. I am fairly sure that fireworks were invented in China long before the USA existed.
I don't like explosions anymore. They freak me out a little and I just don't like loud noises in general. Also, there's nothing more boring than a long fireworks display to Sousa marching music.
Maybe you should try the 1812 Overture.
it's not chinese fireworks, it's freedom fireworks!
Freedom from Britain _and_ Freedom from work yesterday!
Show me ONE geek that does not care about shiny things that go boom!
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Hmmmmmm....We make a lot of noise about it and we watch it go up in smoke, even enjoying it when we don't really think about it, while costing a fortune, but in the end we got nothing but a big show...
Yup, freedom fireworks is quite apt.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Not being an explosives expert, but wouldn't the pellets be pasted on in the inverse of the pattern -- i.e. 1/r in polar coordinates or some such?
On a barely-related note, I was surprised to learn after having moved to Denver that not only are 100% of consumer fireworks banned, but there are also no free professional fireworks displays either (though there are several where you pay for admission). You have to either go on July 3 (missed it) to a park or go to an adjacent city (Aurora, Westminster, Boulder, etc.).
"exciting the electrons in those chemicals into a higher energy state. As they cool down, they move back to a lower state of energy, emitting light."
That's the explanation almost any time you see light, it's not unique to fireworks. It applies to any color of fireworks, regardless of whether the color is produced by the fuel itself or by the fuel heating another element. It also applies to candles, camp fires, butane lighters, acetylene torches, incandescent lights, red hot stove burners, halogen lights, etc.=.
Chill out dude! You don't have to read the article and the small space used on the /. front page is not going ruin your day.
Maybe some of us actually care about how fireworks work. That is a natural geek tendency. What's so wrong with that?
"No matter where you go, there you are." -- Buckaroo Banzai
> > nothing more boring than a long fireworks display to Sousa marching music.
> Maybe you should try the 1812 Overture.
If you want more boring, try something by Johannes Brahms, or Barry Manilow.
HTH.HAND.
Cut that out, or I will ship you to Norilsk in a box.
> explain the chemistry behind the ones that make the big bangs
As a general rule, I think the main active chemical ingredient in those is plain old smokeless powder (which you can easily look up on Wikipedia if you're curious, so I won't duplicate all the details here).
What's more interesting to me is the physics behind the boom. It's very similar to the physics behind thunder. Sudden temperature changes cause a rapid change in volume (Charles' Law in action). The resulting movement creates a sound wave.
Cut that out, or I will ship you to Norilsk in a box.