Determine the number of moles of chromium atoms in 140.0 g chromium(III) oxide.

Answer 1

Chromium(III) oxide = Cr₂O₃

molar mass = 151.99 g / mol

moles Cr₂O₃ = 140.0 g x 1 mol / 151.99 g = 0.9211 moles

moles Cr atoms = 0.9211 mols Cr₂O₃ x 2 mols Cr / mol Cr₂O₃ = 1.842 moles of Cr atoms