[ExI] Ants to spike

[Brent Neal]

On 20 Oct, 2009, at 10:13, spike wrote:

> Anders, precipitating lead from paint chips can probably be done with
> ordinary household chemicals, but not with vinegar.  Mineral spirits  
> or
> turpentine would likely be your best bet for getting the stuff into  
> solution
> to start with.  When you say precipitate it with salt, if you meant  
> sodium
> chloride, you can consult the periodic table and recognize that you  
> would
> form little or no lead chloride.  So I can see at least two things  
> in this
> approach that might explain your result.
>
> I may look up and try to estimate the lead content of paint, which I  
> suspect
> is very low, then sketch a device to extract it from a solution using
> electroplating.  As low as lead is in reactivity and with that +4  
> oxidation
> state, don't get too optimistic.  Might need to figure out a way to  
> extract
> the paint, then evaporate the solvent, then try to separate the lead  
> from
> the rest of the goo that is left over.
>
> Otherwise my guess is try to form a nitrate or a sulfide rather than a
> chloride, then try to extract the lead nitrate or lead sulfide using a
> centrifuge.
>
> Of course if you try to get either sulfuric or nitric acid, you may  
> attract
> the attention of the authorities.


Most likely, Anders failed to extract much lead using 5% acetic acid.  
Lead chloride is well-known in chemistry as one of the three insoluble  
chlorides (the other two being silver and mercury.) The way I would do  
this is to extract in 10% nitric acid. Lead nitrate is soluble in  
water, so the reaction would be

Pb(NO3)2 -> 2NaCl  (or, use 1 MgCl2!) -> PbCl2 + 2NaNO3.

The lead chloride is the only one of these species that is not water  
soluble, so it will drive the reaction to the right. Also, while lead  
does have a +4
  (and a -4!) oxidation state, you'll usually find it in a +2 state.  
The lead pigment used in paint was usually lead carbonate, which is  
clearly a lead(ii) species.

Not a chemist, but I play one at my day job,

B

--
Brent Neal, Ph.D.
http://brentn.freeshell.org
<brentn at freeshell.org>