Chemical test for SnPb lead/ RoHS lead-free solder

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A chemist gave me enough potassium chromate to have a go. Ground off a few
mg from some sheet lead , dropped into some chromate solution and a cloudy
yellowish deposit formed in the otherwise orange liquid - what it is
supposed to do apparently.
Then ground off some known lead free solder , added to some of the solution
and no yellow.
Then ground off some known SnPb solder and again no yellow - so not so
simple a test as first appeared, Pb and tin are combined too well to react ?



Re: Chemical test for SnPb lead/ RoHS lead-free solder


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Why not try one of those inexpensive "sticks" used to test for lead
in paint?  (no idea if it would work)

Re: Chemical test for SnPb lead/ RoHS lead-free solder



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Well, we all knew that SnPb solder was a stable compound that was not going
to break down on its own, allowing cartloads of lead to somehow get into
into the environment, as the eco-bollox lead-free solder brigade, would have
us believe ...

Arfa



Re: Chemical test for SnPb lead/ RoHS lead-free solder


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few
cloudy
react
going
have


That was what I was thinking. And it wold take more than acid rain to leech
the lead from solder, or lead would not be possible to be used as the plates
in car batteries.
The only "lead" test pens I've seen are in paints section of hardware and at
8 GBP a pop and nothing on the package about being used on more than one
occassion, they can stay on the shelves. Those would be for red lead in
paints, which is not elemental lead, so probably would not work either



Re: Chemical test for SnPb lead/ RoHS lead-free solder



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Or of course as lead flashing on every house ever built, or lead guttering,
as is found on many old - and even ancient - buildings, and has been there
for hundreds of years, being 'dissolved away' (ha!) by the rain for all that
time, including the several decades of bad-arsed acid rain, that we had in
the last century ...

Arfa



Re: Chemical test for SnPb lead/ RoHS lead-free solder



Arfa Daily wrote:
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   Some US homes have a sacrificial strip of Zinc along the ridges on
roofs to kill mildew.


--
Greed is the root of all eBay.

Re: Chemical test for SnPb lead/ RoHS lead-free solder



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...

The lead must be in solution to be detected with potassium chromate.

The procedure in my qualatative analysis text book for alloys starts with
disolving a small sample in hot nitric acid.

The reaction with the chromate ion requires that the lead be in solution in
the form of the Pb++ ion.

The test depends on the formation of a yellow insoluble lead chromate.

The test will not work unless the lead is in solution and the pH of the
solution is correct.

There ARE tests that will detect lead without putting it into solution, X-
ray fluorescence for example.

--
bz        73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
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