Re: Aqua regia
- From: Uncle Al <UncleAl0@xxxxxxxxxxxxx>
- Date: Sat, 30 Apr 2005 17:32:55 -0700
Ryn wrote:
>
> I was flipping through my chemistry book a couple of days ago and was
> looking at a problem about the dissolving of gold.
>
> It supplied this equation:
>
> Au(s) + 3NO3-(aq) + 6H+(aq) --> (<-->?) Au3+(aq) + 3NO2(g) + 3H20(l)
>
> When I look at this equation, all it uses is the Nitric acid. Yet, gold
> doesn't react with nitric acid alone. Is the Cl- a catalyst? I looked
> on the internet (though I admit not much because I can only really get
> to google, none of the other pages) and I couldn't find an explanation
> for this phenomenon.
Dissolving gold requires oxidation and complexation. Saline in air
will do it, so will cyanide and air. Aqua regia is a heck of a lot of
acid, NOCl and maybe Cl2 (oxidizing agents), and a heck of a lot of
chloride (complexant).
Writing an equation doesn't mean it happens, thermodynamically or
kinetically. BTW, your equation isn't balanced for material. Where
did the three extra H+ come from?
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.
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