How many oxygen atoms are in 100 g of CO2 sample?
1) mass of substance divided by molar mass = moles of substance 2) moles of substance times Avogadro’s Number = molecules of substance in calculated moles 3) molecules of substance times number of atoms of desired element in one molecule = total atoms of desired element in grams given in problem For desired number of oxygen atoms: with CO2, the last step is times 2; with H2O, the last step is times 1; with SO3, the last step would be times 3.
