Question

what mass of Aluminum contains the same number of atoms as 3.0g Pb?

Answer 1

moles of lead = mass / molar mass

                       = 3.0 / 206

                      = 0.01456

number of atoms of lead = 0.01456 x (6.023 x 10^23)= 8.77 x 10^21 atoms

number of atoms of Al = 8.77 x 10^21

1 mol Al -----------------> 6.023 x 10^23 atoms

x moles Al -------------> 8.77 x 10^21 atoms

moles of Al = 8.77 x 10^21 / 6.023 x 10^23

                    = 0.01456

mass = moles x molar mass

          = 0.01456 x 27

           = 0.393 g

masss of Al = 0.393 g