What quantity in moles of iron atoms do you have if you have 3.40 × 10²³ atoms of iron. (The mass of one mole of iron is 55.85 g.)

Answer 1

One mole, by definition, is 6.02x10²³ atoms/molecules/particles [of anything, actually]. I can have 1 mole of Twinkies, if I hit up enough homes this Halloween. It is a conversion factor when written 6.02x10²³ atoms/mole.

If we have 3.40x10²³ atoms of iron, we have:

(3.40x10²³ atoms Fe)/(6.02x10²³ atoms Fe/mole) = 0.565 moles of Fe

You provided the molar mass of iron (55.85 grams/mole), but the question only asks for moles. If you really, really want to know the mass, then multiply (0.565 moles of Fe)*(55.85 grams/mole) = 31.54 g

Bob