Chemical test for SnPb lead/ RoHS lead-free solder

[N_Cook]

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 ?

 

[D Yuniskis]

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 ?

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

 

[N_Cook]

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

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

 

[bz]

....
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

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.