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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."
Tonight I will welcome our tricky shaped overlords.
and some beer...
Slow news day? Or is this a new "educate-the-readers-in-things-they-don't-care-about" program?
There is no news in the article... It sounds like something a student would copy off wikipedia, mingle a bit, throw in some metaphores, and turn into a school essay.
Did you mean idle? It's posted under news...
"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.
I agree. For the real fun, you need something to blow up. Mythbusters isn't popular because the grenades they use produce nice colorful images upon exploding inside that fridge.
It's July 4. I'm going to watch fireworks today, so Slashdot posted something about fireworks.
Freedom from Britain _and_ Freedom from work yesterday!
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.=.
TFA goes to a story from a year ago... and this should be in idle, but never the less it is here now so get your geek on!
On a related note: Naked Science did a nice bit on Fireworks last week.
Secret World of Fireworks
This book is what I would recommend for those who want to delve into the science behind pyrotechnics.
233 years and still leaving naysayers stumped like rain forests!
Now let's take it back to what it stood for those 2 centuries ago and throw the Democran and Republicrat bums out.
when Gandalf would show up with a wagon full.
Someone might enjoy these two programs which allow fireworks-like effects: http://dan-ball.jp/en/javagame/dust/ http://powder.unaligned.org/ http://www.youtube.com/watch?v=MESkoRgSeJo http://www.youtube.com/watch?v=Jdf2JSKHWe0
Come to France where they sell consumer fireworks in children's toy shops, to children!
This includes 'bangers' (fire crackers or 'petards' in French) which have been banned in the UK.
I don't know how blackbody radiation is generated, if not from electrons dropping into lower energy states, but isn't it possible to get blackbody radiation from materials completely lacking electrons? Even for normal materials hot enough to glow, how do you get the essentially-continuous spectrum of blackbody radiation?
Blackbody radiation is an approximation, assuming that a material can emit a spectrum of photons of different energies. All light is a result of moving charge, most commonly from electronic transitions, and when you take into account the actual quantum physics of an atom or group of atoms (macroscopic material), you won't get actual blackbody radiation. For example a perfect (pure) semiconductor at a high temperature will not emit light with energy less than the band gap energy, but for energies above the band gap it will look roughly like a blackbody.
My mistake... I was describing luminescence (electron jumps) but the examples were incandescent (thermal vibration of atoms). It's still the "cooling" that you see, whether it be excess energy from the atom or the electron.
http://library.thinkquest.org/27356/p_sources.htm
...It's because we celebrate the birth of our country buy BLOWING STUFF UP!
Any insufficiently advanced magic is indistinguishable from technology.
... and explain the chemistry behind the ones that make the big bangs around my neighborhood. The ones that sound like ordnance stolen off the nearby military base.
Have gnu, will travel.
Though not really applicable to general category of "shiny things that go boom", definitely true in the case of fireworks.
Really, why do people feel the need to propel thousands tons of chemicals into the air and just let them explode?
One that hath name thou can not otter
I used to get a kick out of just flushing an explosive device down a toilet. The crap flies out in a pattern determined by this mathematical formula...um...I had it just a moment ago.