brisance
Harmless
Posts: 12
Registered: 14-12-2004
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K3Cu(CN)4 + H2O2
As part of my science fair project, I am observing the luminol reaction found on Purdue's Chemistry website. However, when I looked this website up on my instructor's website, the "solution B" appeared to include the
bullets of H2O2 and water below it. Consequently, I mixed the following (fortunately, under a fume hood):
75 ml of 10% H2O2
with
solid .213g K3Cu(CN)4
Upon mixing, the solution quickly turned from clear to brown (similar to the color of a coca-cola). Bubbles evolved, and continued for at least 15
minutes. My instructor had to leave, so we left the solution, with bubbles still evolving. (The reaction could still be proceding as I type this).
He proposed that copper was being oxidized to free metal copper and that the bubbles evolving were oxygen. This seems counter-intuitive to me; I
don't understand where one of the cyanide ions would go.
My question is this: Does anybody know what reaction just occurred?
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BromicAcid
International Hazard
Posts: 3227
Registered: 13-7-2003
Location: Wisconsin
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Solutions of copper cations with H2O2 behave similarly to Fenton's Reagent and will oxidize organic components.
A quick search in google with "peroxide copper cyanide" shows that solutions of copper with peroxide are indeed used to destroy cyanide. So
your gasses are probably, for the most part just O2 [H2O2 decomposing], but the cyanate produced can hydrolyze depending on the pH to give ammonia,
and carbon dioxide. So these may be mixed in along with a little HCN.
Check out this fact sheet on cyanide destruction
BTW: | Quote: | | He proposed that copper was being oxidized to free metal copper |
Copper would be 'reduced' to the
free metal, to be oxidized would be to bring it further from being a free metal, in this case copper is +1 so it could go to +2 readily in this
enviorment but reduction to the free metal is significantly less likely.
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