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Topic: Colored flames in methanol  (Read 8731 times)

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Offline vaselinessa

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Colored flames in methanol
« on: November 12, 2011, 08:03:17 PM »
I'm trying to get a variety of colored flames by dissolving salt and methanol (after the fashion of this YouTube video et al.: http://www.youtube.com/watch?v=3LruNzqA8Xw).

I'm doing alright with strontium chloride solution and boric acid solution. But I'm not having luck with sodium chloride or potassium chloride or cupric chloride.

Regarding NaCl and KCl, I can't really get either to dissolve in methanol. As a consequence, I just get the clear/blue methanol flame, not yellow nor purple. Anyone have any advice?

As for cupric chloride, I get a green flame, not the blue one from the video (at least I think the voices in the video say it's blue; even in the video it looks rather green).

Lastly, can anyone suggest what containers are being used in the video (holding the flaming methanol)? I used an ordinary glass dish, but the heat caused it to break on me twice.

Offline Arkcon

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Re: Colored flames in methanol
« Reply #1 on: November 13, 2011, 07:40:38 AM »
Step one: use a Pyrex(TM) glass dish or a ceramic dish.  Or a steel dish.

I've mentioned before, it will be hard to see the purple flames with the potassium ion, its a weak color, and our eyes are not optimized for those short wavelength, so it gets washed out by traces of sodium.  Consider using cobalt if you need a purple-ish flame, or stick a cobalt blue glass filter in from of your camera lens.

Copper salts give a green flame test.  Pyrotechnicists will tell you, you can get a blue flame, with copper salts, if chlorine is also present (you're halfway there) and ammonium ion is also present.  So add some household ammonia.

It will be hard for a layman to find a cheap, safe, source of sodium and potassium salts that are alcohol soluble 'tho.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline vaselinessa

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Re: Colored flames in methanol
« Reply #2 on: November 14, 2011, 12:43:03 PM »
Thanks, Arkcon. I'll look into cobalt. As for ammonia, I tried adding a bit to the cupric chloride but did not have good results. Can you say anything about concentration (amount) or method?

And wouldn't I need to add HCL to ammonia in order to get ammonium? And wouldn't that be dangerous? I mean, what would keep the NH4 and Cl ionized, as opposed to releasing chlorine gas?

Offline Arkcon

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Re: Colored flames in methanol
« Reply #3 on: November 14, 2011, 01:13:51 PM »
Copper salts from an ammonical complex, so just mixing some in should form the complex and get the the blue color.  Note:  I prepare a tiny amount, adsorb onto cotton wool,  add alcohol fuel, and get some blue flame for a short time.  If you're preparing a huge amount for a stage presentation or something, then yes, you will have to consider the fumes, and talk to a pyrotechnist.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline vmelkon

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Re: Colored flames in methanol
« Reply #4 on: November 14, 2011, 02:13:05 PM »
Regarding NaCl and KCl, I can't really get either to dissolve in methanol. As a consequence, I just get the clear/blue methanol flame, not yellow nor purple. Anyone have any advice?

You probably have pure methanol. Add 20% salty water and it should do the job.

Offline vaselinessa

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Re: Colored flames in methanol
« Reply #5 on: November 16, 2011, 01:07:25 PM »
Add 20% salty water and it should do the job.
Thanks. That made a difference. Looks like I have a little fine tuning to do.

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