symboom - 27-2-2017 at 06:11
I have mixed sodium dithionite and copper sulfate
I have this odd green percipitate is copper dithionite formed?
Σldritch - 6-3-2017 at 11:21
Tried this and got a brown precipitate and horrable smell.
DO THIS OUTSIDE!!!
Still filtering, will return with results if alive in a bit.
EDIT:
It is a red brown powder which does not dissolve in 30% HCl but does dissolve very rapidly in 12% H2O2 and 30% HCl mixture so i assume it is very fine
copper particles. Judging from how fast my copper nanoparticles (Made by chemplayers method but not tested) react this copper powder is even finer
since it reacts much quicker with the Hydrogen peroxide and HCl.
Maybe this happens because the reaction is autocatalytic.
When the copper is reduced it liberates sulfuric acid which catalyses the decomposition of dithionite which itself autocatalyses its own decomposition
giving the particles less time to grow.
CuSO4 + 2 [e-] + 2 H+ > Cu + H2SO4
From Wikipedia:
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An aqueous solution of sodium dithionite is acidic and decomposes to sodium thiosulfate and sodium bisulfite. The reaction rate increases with
increasing temperature. In addition, the rate is higher under stronger acidity.
2 Na2S2O4 + H2O → Na2S2O3 + 2 NaHSO3
In presence of oxygen, it decomposes to sodium bisulfate and sodium bisulfite.
Na2S2O4 + O2 + H2O → NaHSO4 + NaHSO3
Sodium bisulfate and sodium bisulfite decrease the pH and therefore accelerate the reaction. Sulfur dioxide is formed under strongly acidic
conditions.
2 H2S2O4 → 3 SO2 + S + 2 H2O
3 H2S2O4 → 5 SO2 + H2S + 2 H2O
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The reagents i used was:
Copper Sulfate pentahydrate 10g
Sodium Dithionite 7g
Both were dissolved in water, mixed together and vacuum filtered
[Edited on 6-3-2017 by Σldritch]
[Edited on 6-3-2017 by Σldritch]