[Amps] current threads about silver solder and resoldering

[Manfred Mornhinweg]

Roger,

are you kidding us, or are you applying reversed logic today? ;-)

> Lead = 207.2
> Tin 118.7

Yes, that's right. That's the weight of these elements, expressed in 
grams per mole of atoms. One mole is roughly 6.022*10^23.

> Figuring gram molecular weights
> 
> 63% of 118.7 = 74.781grams/molecules
> 37% of 207.2 = 76.664grams/molecules

But this just isn't the correct calculation to do!

Let's take a real, practical and simple example. Assume you have a 
little 100 gram spool of 63/37 solder (and let's forget that a small 
amount of those 100 grams is the flux...). So you have 63 grams of tin 
and 37 grams of lead there, right? That's simple enough, I guess...

If one mole of tin atoms weighs 118.7 grams, then 63 grams of tin is 
0.5307 moles of tin atoms.
And with one mole of lead atoms weighing 207.2 grams, 37 grams of lead 
is only 0.1786 moles of lead atoms.

Thus it follows that the ratio of tin atoms to lead atoms in this solder 
is 2.971, or roughly 3:1, and in any case very different from 1:1.

OK?

Manfred

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