Do I really have to think? :mrgreen:
OK, here goes;
Mole Definition: a chemical mass unit, defined to be 6.022 x 1023molecules, atoms, or some other unit.
This means we are comparing the number of atoms of each element in our alloy.
1 gram of copper = 0.0157366317313 moles
1 gram of lead = 0.00482625482625 moles
1 gram of tin = 0.00842389015247 moles
1 gram of antimony = 0.00821287779238 moles
1 gram of arsenic = 0.013347285696 moles
So supposing you have 1 kg of lead to which you add 100g of tin and 100g of antimony and 25g of copper and 1 gram of arsenic,
we get;
1000x0.00482625482625 = 4.826 moles of lead
100x0.00842389015247 = 0.842 moles of tin
100x0.00821287779238 = 0.823 moles of antimony
25x0.0157366317313 = 0.393 moles of copper
1x0.013347285696 = 0.133 moles of arsenic
Total = 6.8973 moles
lead = 70.0 %
tin = 12.2%
antimony = 11.9%
copper = 5.7%
arsenic = 0.19%
Doing the percentage by mass we get;
Total weight = 1226 g
lead = 1000 g = 81.6 %
tin = 100 g = 8.2 %
antimony = 100 g = 8.2 %
copper = 25 g = 2 .0%
arsenic = 1 g = 0.08%
Note how the copper jumps from 2% by mass to 5.7% by mole.
I've updated my alloy calculator from
bumpo628 to show moles and mole percentages. It makes the copper percentage more meaningful.