budullewraagh - 13-8-2004 at 17:50
the other day i was looking through my "lange's handbook of chemistry" and i stumbled upon a table that had many compounds and their
solubilities in H2O at various temperatures. out of curiousity, i looked for the most soluble compounds. i found antimony trichloride and found that
at 40 celcius, 1368g of it can dissolve in 100mL H2O. it said that at 72 celcius it is completely miscible.
does anybody here find it to be possible to continuously add SbCl3 to H2O and NEVER precipitate it? i'll throw around some figures:
121.760+3*35.45=228.119=1 mole SbCl3.
1368/228.119=5.996870055M=saturated solution of SbCl3 in 100mL H2O.
100/18=5.5555 (repeating).
there are more moles of SbCl3 than H2O at 40 celcius. therefore there are more molecules of SbCl3 than H2O at 40 celcius. the number of H2O molecules
is only 92.64091942% of the number of SbCl3 molecules there are. the Sb+3 migrate towards the O end of H2O while 3 Cl- atoms migrate towards the H in
H2O.
that makes sense, except the Sb+3 and Cl- are so close to one another when in this saturated aqueous solution that i don't see why they
don't precipitate.
also i'd like to add that the above calculations are only for the 40 celcius reading; again, at 72 celcius SbCl3 is "completely
miscible".
can anybody help me out?
BromicAcid - 13-8-2004 at 18:58
It's easier to consider this an eutectic system, the water acts to depress the melting point of the antimony trichloride (Mp ~73 C) and therefore
make the system liquid at a much lower temperature, it is more the H2O getting between the weak bonding between SbCl3 molecules then actual solvation
it would seem.
Also the melting point makes it clear why it is miscible at 72C, it is basically a molten salt at this point and it just happens to be miscible with
water.
You could add enough SbCl3 to a volume of water to where it would precipitate some out or just not dissolve any more but then the whole mass might
come out of solution as it might divide up the water between itself in such a way as to render the water in the system insufficent to keep everything
liquid any more, another drop or two though and everything might go back into solution.
Antimony Trichloride
chloric1 - 14-8-2004 at 17:39
Interesting to note that if you have a large excess of water the chloride hydrolisized to the oxychloride. My recently purchased book "Advanced
Inorganic Chemistry" states Antimony Trichloride can be isolated anhydrous from concentrated Hydrochloric acid!
Since the trisulfide is HCl reactive, I will be searching for this next time.
Purhaps when I have my CL generator completed, I could use it to make antimony pentachloride! This would be for organic chlorinations and ,if I can
develope a stainless steel still, with anhydrous HF I could isolate the pentafluoride! Oh my I am getting carried away!
budullewraagh - 14-8-2004 at 18:19
oh lord, don't make pentafluoroantimonic acid
Hehehehe
chloric1 - 14-8-2004 at 21:10
Yesss! Ima naughty boy!!