F. Law of Conservation of Mass In any physical or chemical reaction, mass is conserved. Mass can neither be created nor destroyed

F. Conservation of Mass Cont. During any chemical reaction, the mass of the products is always equal to the mass of the reactants. Reactants  Products Massreactants = Massproducts

F. Conservation of Mass Practice Mercury (II) oxide is heated and forms 200 grams of mercury metal and 16 grams of oxygen gas. How much reactant did you start with? 2HgO  2Hg(s) + O2 ?? 200 g 16 g Mass of HgO = 200 g + 16 g = 216 g

F. Conservation of Mass Practice 10.00 grams of mercury (II) oxide is heated. 9.26 grams of mercury metal remains in the flask. How much oxygen formed? 2HgO  2Hg(s) + O2 10.00 g 9.26 g ?? Mass of O2 = 10.00 g – 9.26 g = 0.74 g