Avogadro's number was established as the total number of units (atoms or molecules) in a mole, and a mole of any substance is X grams of it, where X is equal to the substance's molecular weight.A standard unit, the mole, allows scientists to calculate concentrations of materials dissolved in solutions. Example: Sulfur has a molecular weight of 32.Therefore, 32 g of sulfur = 1 mole of sulfur = 6 × 1023 sulfur atoms. How many moles and atoms, respectively, are there in 120 grams of sulfur?