Sciencemadness Discussion Board

Chromium(III) Carbonate???

iloveloli - 27-12-2015 at 09:30

i have a mixture...
(it come from K2Cr2O7,H2SO4,methol,Isopropanol and h20)
i think i hed added enough Isopropanol to make all of the K2cr2O7 to from
Cr(III)
then, i add this mixture to sodium carbonate solusion......
CO2 come out, and some gray blue(i don't know how to discripe...)precipitate.
??????????The precipitate is Chromium(III) Carbonate??????????????
but i think Chromium(III) Carbonate should be green..............


[Edited on 27-12-2015 by iloveloli]

UC235 - 27-12-2015 at 09:41

Doesn't exist. Post in short questions thread next time. Detritus.

mayko - 27-12-2015 at 10:28

Check Mellor, vol.11/ch.60, in the forum library. There's a great deal on chromous (II) carbonates, as well as this blurb which might be relevant to your observations. (Be aware that there are many mentions of the nearly mythical copper carbonate in this text!)
Quote:

According to H. Rose, alkali carbonates precipitate from soln. of chromic salts
a pale green hydroxide containing more or less carbonate, which on standing
becomes blue in daylight, and violet in artificial light. An excess of the precipitant
dissolves the precipitate, and the soln. gives no precipitate when boiled ; potassium
or ammonium hydrocarbonate behaves similarly; but barium carbonate slowly
precipitates hydrated chromic oxide completely from cold soln. J. N. von Fuchs
made a similar observation with respect to calcium carbonate ; and H. Demarcay,
with respect to strontium and magnesium carbonates. K. F. W. Meissner, J. Lefort,
and T. Parkman obtained basic chromic carbonates by the action of alkali or
ammonium carbonate on a soln. of a chromic salt. M. Hebberling added that the
freshly-formed precipitate is soluble in soln. of alkali carbonate or borax. The
composition of the precipitate depends on the conditions; thus, K. F. W. Meissner
gave 10Cr2O3.7OO2.8H2O ; J. J. Berzelius, 4Cr2O,.CO2.H2O; and C. Langlois,
2Cr2O3.CO2.6H2O

Amos - 27-12-2015 at 10:38

It's chromium(III) hydroxide. The carbonate doesn't exist. Please someone detritus this, I have eye cancer after reading this.