Question

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

(1 mol Mg/1 atom Mg)

(1 mol Mg/3.48 x 1018 atoms Mg)

(1 mol Mg/6.02 x 1023 atoms Mg)

(6.02 x 1023 atoms Mg/1 mol Mg)

Answer 1

The first fact you should know to solve a stoichiometric problem like this one is that, there are 6.02 x 10^23 particles (atoms or molecules) in 1 mole of a substance.

Now, to know the equivalence factor, it is important to know a technique which cancels like units when they are placed diagonally. Hence, to find the moles Mg from atoms, the equivalence factor must have a numerator with units of moles and a denominator with units of atoms. In this case, atoms would be cancelled, leaving the moles.


`3.48 x 10^(18) \ atoms\ ( (1 \ mole)/(6.02x 10^(23) \ atoms ) ) = 5.8x 10^(-6)`