booboy
Harmless
Posts: 4
Registered: 6-9-2012
Member Is Offline
Mood: No Mood
|
|
Barium oxalate under microscope
I wanted some Barium Oxalate (no particular reason, just another reagent to add to my collection). I know that Barium Oxalate precipitates out rather
slowly, so I preapared solutions of Barium Chloride and Oxalic Acid in stoichiemetric proportions and mixed the two. I immediately placed a small
drop of the mixture onto a microscope slide, and was able to view the slow growth of crystalline product. Fascinating!
Anyone know of any other similar that I could try?
NOTE. I should point out that I was seeing the crystals PRECIPITATING out of solution, not crystallizing out as the solution evaporated.
[Edited on 15-4-2013 by booboy]
|
|
|
Mailinmypocket
International Hazard
Posts: 1351
Registered: 12-5-2011
Member Is Offline
Mood: No Mood
|
|
I have made a sulfur solution in carbon tetrachloride and played a drop on a slide, watch the solvent evaporate and the sulfur crystals grow. Quite
nice  you could also use carbon disulfide or toluene as well.
|
|
|
booboy
Harmless
Posts: 4
Registered: 6-9-2012
Member Is Offline
Mood: No Mood
|
|
Thanks, I'm not sure how readily available these chemicals are here in the UK, but I'll look around. Not sure I want to handle the CS2 though, I get
enough
rotten cabbage smell from the wife's cooking!
[Edited on 15-4-2013 by booboy]
[Edited on 15-4-2013 by booboy]
|
|
|
Mailinmypocket
International Hazard
Posts: 1351
Registered: 12-5-2011
Member Is Offline
Mood: No Mood
|
|
Toluene should be easy enough to find, I hear you about the CS2 stink though... Toluene may in fact make nicer crystals since it evaporates slower
than the other two solvents (and smells rather nice too, in my opinion anyways). You might also want to try making a small puddle of water on a slide
and placing a crystal of potassium iodide in one end, and some lead nitrate in the other. When the chemicals dissolve and the fronts meet, you will
see the precipitate of lead iodide in close detail. Forum member Woelen has a page on his site about this (although not under the microscope I
believe) that you might want to check out.
Watching silver crystals form with copper and silver nitrate is nice, same with acidified tin chloride and metallic zinc- watch tin crystals grow.
Various organics in volatile solvents like dichloromethane are nice to watch crystallize under the microscope too, some more impressive than others.
|
|
|
booboy
Harmless
Posts: 4
Registered: 6-9-2012
Member Is Offline
Mood: No Mood
|
|
Thanks again, certainly a few things to try there.
Currently, I don't have a large stock of reagents, which is one reason why I synthesise my own where possible.
I don't have any lead or tin salts, although I think I could get some lead (probably as the carbonate) from pottery supplies. (From whence I obtained
the Barium Carbonate)
When I was working, I could get almost anything I needed, pity I didn't 'squirrel some away' before I retired. (But that would have been stealing, so
nono there).
Thanks again for the reply and the ideas. 
|
|
|
DraconicAcid
International Hazard
Posts: 4295
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
I've had great results with a sliver of copper foil and a drop of silver nitrate solution.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
Hmm, anything that dissolves in MeOH or EtOH, say, vanillin would be good?
Tim
|
|
|
booboy
Harmless
Posts: 4
Registered: 6-9-2012
Member Is Offline
Mood: No Mood
|
|
Thanks DA, the Cu foil and AgNO3 worked a treat!
Thanks also to 12AX7, I haven't tried this yet. Don't have any Ethanol (except in the form of white rum), but I have Methanol aplenty.
I also don't have any Vanillin, but I'm inclined towards using Ascorbic Acid.
|
|
|
mayko
International Hazard
Posts: 1218
Registered: 17-1-2013
Location: Carrboro, NC
Member Is Offline
Mood: anomalous (Euclid class)
|
|
I got good results with crystallizing vitamin C from isopropanol. It would start to crystallize at nucleation sites, with a largish crystal forming at
the site and a wave of crystallization spreading out radially. What was especially interesting is that the wave slowed down as it traveled, finally
stopping (critical slowing down?). At this point, new nucleation sites on the outer edge of the circle will spawn new waves of crystallization. This
is very cool under the scope! For extra flair, add some polarizing filters. The ascorbic acid molecule is chiral, and should rotate polarized light to
different extents according to wavelength, which should result in some pretty colors
|
|
|
Eddygp
National Hazard
Posts: 858
Registered: 31-3-2012
Location: University of York, UK
Member Is Offline
Mood: Organometallic
|
|
Well, I have seen many crystallisations and precipitations under the microscope: CuSO4, Cu(OAc)2, PbI2, CoBr2, etc.
It actually depends on what you want to see. I personally enjoyed the PbI2 precipitation (and I later dissolved it in hotter water to crystallise it
too, under the microscope), but I suppose that many other ones are equally satisfying.
there may be bugs in gfind
[ˌɛdidʒiˈpiː] IPA pronunciation for my Username |
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
