bismuthate - 28-9-2013 at 05:47
i took some zinc hydroxide and dissolved it in NaOH then i took the mixture and added a solution of copper sulfate. this formed a dark blue
percipitate that looks nothing like copper hydroxide is this copper zincate of a big mistake?
blogfast25 - 28-9-2013 at 09:22
In all likelihood your precipitate is Cu(OH)2, coloured darker than usual due to some cuprate formation. In very alkaline conditions,
copper hydroxide forms Cu(OH)42- (cuprate anions) which are deep cobalt blue. Copper (II) is amphoteric.
But even without cuprate formation, it's unlikely a copper zincate was formed due to the extreme insolubility of Cu(OH)2 and the alkalinity
of sodium zincate solutions.
[Edited on 28-9-2013 by blogfast25]
JasonHerbalExt - 28-9-2013 at 19:32
I did't find out copper zincate's Ksp. I guess OH- binds Cu2+ first. ....There are ZnO2- in the solution....So, I dont know.
12AX7 - 29-9-2013 at 02:58
More likely you'll form an alloy oxide by fusing them at high temperature. I don't know what the oxide phase diagram looks like; there might be an
intermediate compound (which might be a "zincate") but it may simply be a eutectic system (the melting point is depressed by combining them, but they
crystallize separately). Don't see it happening in aqueous solution.
Another intriguing question: is there such a thing as chromium(III) chromate(VI)? (Probably dichromate given the pH range of both ions. And
depending on the ligands of the cation.) Would it precipitate CrO2 on dehydration? What about other transition metal cations and anions? (For
example, something like copper chromate is already fully oxidized and can't disproportionate to intermediate states.)
Tim
bismuthate - 29-9-2013 at 03:27
i can't study it because after a while it decomposed to a mix of white powder and light blue powder. these are probable the hydroxides