Na2SO4 (Sodium Sulfate) Molar Mass
Finally, add together the total mass of each element to get the molar mass of Na2SO4: 45.97953856 g/mol + 32.065 g/mol + 63.9976 g/mol = 142.04213856 g/mol. 5. Find Mole Fraction. To find the mole fraction and percentage of each element in Na2SO4, divide each total from step 3 by the total molar mass found in step 4: