Sublimation of the Arsenic in the open tube & atmospheric pressure

Arsenic is one of few elements which does not melt at the normal pressure (another one is Carbon). So if you heat it in the open test tube it start to sublime and condense on the colder part of the tube.

Category:

Education

Tags:

• Arsenic
• sublimation
• melting
• chemistry
• demonstration
• experiment

[endimion17]

@10mintwo It seems this is a recognized phenomenon. I'll try to investigate it further, thanks. :)

[10mintwo]

@endimion17 I recommend "The Sodium and Potassium Absorption Bands" in PRL from 1927, "Continua in the visible absorption spectrum of K2" JOSA 1985, "Absorption cross sections of alkali-vapor molecules" JOSRT 1966, and the other couple references noted in the video.

[endimion17]

@10mintwo It's interesting that it seems that guy's blog is the only source of this information on the Web. I can't find references he mentioned.

I'll remain skeptical until further notice.

I'd expect that even the earliest chemists who worked with potassium would notice that phenomenon and it would be widely known. After all, it's pretty neat stuff.

[10mintwo]

@endimion17 You would think that, wouldn't you! That's what I thought. But alkali metal vapors DO in fact show deep coloration. Search for "potassium vapor green" and watch the first video. The reason you couldn't see it in the periodic table video guy's video is probably because it was performed in vacuum where the mean free path of an atom in the vapor state is huge and didn't give enough time to accumulate in sufficient amount before being redeposited on the cool portion of the glass.

[endimion17]

@10mintwo There's no reason why would a metal fume have vivid colors. Guys at the periodic table videos did it with potassium. No colors. Just potassium mirror, much brighter than the arsenic mirror.

[10mintwo]

Great! Is there any chance you could try this with K or Na in an atmosphere of Ar? I hear the vapors have vivid colors.

[InsideOutN]

Cool video, once again. Also, I learned something new, so thumbs up.