Science Fair Time Again

Monday, March 9, 2009 

Isabella likes colors. And fire. So she wanted to make colored fire. We tried a lot of different techniques, some we found on the interwebs and some we made up to make colored flames from various chemicals we got from United Nuclear.

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We tried my childhood Bunsen burner with straight ethanol which didn’t work out so well. Contaminating the wick with chemicals was effective, but not in distinguishing between sample chemicals.

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Then we tried soaking the a pile of the chemical under test in ethanol and setting it on fire in a watch glass, which was a lot of fun, but didn’t do so well in the distinguishable colors dimension and a bit of a pain in the ass to clean the watch glass between samples.

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We tried using a 316L 3/16″ welding rod hammered into a shallow spoon as a chemical scoop (one for each chemical) and holding it the flame of a propane torch. This worked pretty well but some chemicals (copper oxide for example) didn’t really do much until the rod was white hot, and even then there wasn’t too much color. Others (lithium carbonate) worked really well.

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We got some Nichrome wire from McMaster and made an electric loop. We dipped the wire in clean water and then in the chemical under test (Lithium carbonate first) and then ran about 8-9A through the wire until it was white hot. It looked promising, but then the wire melted and burned through.

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Iron Filings

So we used little loops of the NiChrome wire to hold samples in the propane flame. The 0.020″ wire heated a lot faster than 3/16″ welding rod and the results were more satisfactory, though Barium Carbonate was yellow orange, not green as expected.

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Barium Carbonate

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Calcium Carbonate

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Copper Oxide

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Cryolite (Sodium) [not a lot of differentiation between yellows]

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Lithium Carbonate

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Zinc dust

The best assortment we tested would be Cryolite, Lithium Carbonate, Zinc, & Copper Oxide which yield a bright, easy to reproduce, and clearly differentiated spectrum of colors.

Next we build a simple spectroscope and see what the emission spectra looks like.

Posted at 00:42:04 UTC

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