Black flames

[andrewtretiakov]

Be afraid be very afraid of black flames! This is a great demo for Halloween.
All about atomic emission and absorption spectroscopy as well as quantum theory.

Black flames 1

Black flames 2

Black flame 3

When performing flame tests in the teaching lab, we ignite ethanol with different metal salts to observe the characteristic emission spectra. In this case, we added table salt or sodium chloride to produce the yellow-orange flames. This is caused by unstable excited electrons in sodium atoms that fall back to a more stable energy level or ground state emitting almost monochromatic yellow at 589 nm in the process. A low pressure sodium lamp placed right next to the flames also emits the same wavelength. The flames absorb that light & appear an eerie black.

Here's a short video:
https://youtube.com/shorts/8gZWSHxtHiw? ... mOP-NADL8d

#spookychemistry

[lemmi]

Very impressive pictures! Perfect for halloween - congratulations!

We have this experiment already documented here. But it seems that your version of burning alcohol with sodium chloride gives more impressive results.

[MarbsLab]

I'll have to repeat the experiment one day. Phillips, for example, offers sodium vapor lamps. Nice work.

Cheers

Markus

[andrewtretiakov]

Very impressive pictures! Perfect for halloween - congratulations!

We have this experiment already documented here. But it seems that your version of burning alcohol with sodium chloride gives more impressive results.

Thank you! Yes, the flames look almost like a CGI effect. Difficult to believe until you see them.

Cheers, A

[andrewtretiakov]

I'll have to repeat the experiment one day. Phillips, for example, offers sodium vapor lamps. Nice work.

Cheers

Markus

Yes, please do and let me know how it goes. Easy to prepare and very impressive in person.
Thank you Markus.

[mgritsch]

Thank you! Yes, the flames look almost like a CGI effect. Difficult to believe until you see them.

I agree, this is not new but by far the very best way to demonstrate it, have never seen it presented this cool!

[SebastianV]

Why cry?

Were can I buy a sodium lamp? What is the cheapest lamp?

[Glaskocher]

This may work, but not tested yet:
If you have a strong bunsenburner or better a glassblowers torch you can heat glass in the flame to get a lot of sodium light. Put a shade between the torch and your alcohol fire with salt and a white screen behind both.

[BJ68]

Why cry?

Were can I buy a sodium lamp? What is the cheapest lamp?

viewtopic.php?f=33&t=6009&p=90158


bj68

[aliquis]

Were can I buy a sodium lamp? What is the cheapest lamp?

https://www.grow-shop24.de/250w-ndl-nat ... 9wQAvD_BwE

[BJ68]

https://www.grow-shop24.de/250w-ndl-nat ... 9wQAvD_BwE

It looks not like a "Low pressure sodium" lamp....so can not use it....it has to be low pressure

see "Since the high pressure sodium vapor lamp belongs in a rather low price range,..." https://www.growland.biz/Elektrox-Super ... -400W-600W

Edit: Search for "Philips SOX"

bj68

[aliquis]

What makes the difference for the desired effect? The wave length?

Some of those sox bulbs are sold as halogene lamps...

[mgritsch]

What makes the difference for the desired effect? The wave length?

Only low pressure lamps emit the narrow line spectrum that can also be absorbed and results in the „black flame effect“.
In high pressure lamps the Na atoms interact forming bands which results in a broadening of the lines and eventually a more or less continuous spectrum. Check it, most street lights (especially on city highways) these days are Na high pressure. You don’t get black flames.

[Glaskocher]

... and you don't see the shadow of the flame on the ground...