An impure sample of barium hydroxide, Ba(OH)2(aq), has a mass of 0.540 g. It is dissolved in water and then treated with excess sulfuric acid, H2SO4(aq). This results in the formation of a precipitate of barium sulfate, BaSO4(s). H2SO4(aq) + Ba(OH)2(aq) → BaSO4(s) + 2H2O(l). The barium sulfate is filtered, and any remaining sulfuric acid is washed away. Then the barium sulfate is dried and its mass is measured to be 0.62 g. What mass of barium hydroxide was in the original (impure) sample?