Question

Which equivalence factor should you use to convert from 3.48 x 1018 atoms of magnesium (Mg) to moles of magnesium?

Answer 1

1 mol/6.022x10^23 atoms.
If you multiply 3.48x10^18 atoms by the conversion factor, 1 mol/6.022x10^23 atoms, the atoms cancel out in the division problem, and you are left with 5.78 x 10^-6 mols of Mg.

Answer 2

By definition, 1 mol is equal to the number of atoms in 12 grams of carbon-12. It's a defined quantity, like a dozen for example. A dozen is always equal to 12. If you have 5 eggs, and multiply that by the conversion factor 1 dozen/12 eggs, you are left with the fraction 5/12 dozen.