How many moles of phosphorus atoms do you have if you have 4.60 × 10²² atoms of phosphorus. (The mass of one mole of phosphorus is 30.97 g.)

Answer 1

Simply use dimensional analysis along with Avogadro's number (6.02x10²³ atoms/mole):

4.60x10²² atoms x 1 mole / 6.02x10²³ atoms

Note that atoms cancel, leaving you with moles

4.60x10²² atoms x 1 mole / 6.02x10²³ atoms = 0.764x10^-1 moles = 7.64x10^-2 moles