How do you find the number of individual atoms in the piece of foil from the mass?

Question

My piece of Aluminum foil has a mass of .19 g
Is this a conversion problem? I keep setting it up with Avogadro's Number, but it seems wrong to me.

Answer 1

You have to divide that by the atomic mass of aluminum (which yu fan get off of the periodic chart) That gives you the number of gram-equivalents of aluminum. This is also known as 'moles'. Now multiply that by Avogadros number to get the number of atoms.

Doug