MrHomeScientist - 26-12-2018 at 11:48
Recently Metallium put a really cool sample up for sale: a vial of liquefied NO2 encased in resin. There isn't a direct link, but it should
appear at this page for a while: http://www.elementsales.com/newp_2017.htm
Here's the picture from that link:
It's green! If you look at the image on wikipedia, however, it goes from dark brown to colorless depending on temperature:
https://en.wikipedia.org/wiki/Nitrogen_dioxide
What causes the green color?
Ubya - 26-12-2018 at 12:31
brown to colorless with green in between? that's odd, but cool sample anyway
ninhydric1 - 26-12-2018 at 14:03
It looks like a mix of N2O3 (bluish tint when pure) and NO2, however, that would signify NO contamination, so I have no clue, unless the sample isn't
pure.
WGTR - 26-12-2018 at 17:00
Here is a thread with the same question. I did a small experiment to show the production of N2O4 without significant
contamination.
https://www.sciencemadness.org/whisper/viewthread.php?tid=93...
It's possible that the sample of NO2 from Metallium had enough moisture contamination to produce acid and NO, giving the green or blue
coloration (depending on N2O3 concentration).
This is some N2O3 that I produced, sitting as a dense blue layer underneath some HNO3:
https://www.sciencemadness.org/whisper/viewthread.php?tid=84...
Basically, there's not quite enough oxygen in his sample to get the colorless or straw color.
[Edited on 12-27-2018 by WGTR]
MrHomeScientist - 27-12-2018 at 11:03
Neat! That sounds very plausible. The dark blue of N2O3 mixed with brown NO2 would seem to explain it. I know
NO2 goes from brown to colorless at low temperature, so I wonder if this sample would go from geeen to blue, or if the blue is also
affected by temperature. That sounds like an interesting challenge to make pure, brown liquid NO2!