1. Law of Conservation and Law of Definite Proportions

2. Law of Conservation of Mass
Matter cannot be created or destroyed
Total mass of reactants = total mass of products

3. Law of Conservation of Mass
Cu + S → CuS If 2.25g of copper completely reacts with 3.32g of sulfur, how much product will be formed?

4. Law of Conservation of Mass
3CuCl2 + 2Al → 3Cu + 2AlCl3 8.60g of copper (II) chloride completely reacts with 10.00g of Al. If 5.76g of copper forms and 10.09g of aluminum chloride forms, how much aluminum was extra?

5. Law of Conservation of Mass
NaOH + HCl → NaCl + H20 If 22.85g of sodium hydroxide and 20.82g of hydrochloric acid react and 10.29g of water forms, what mass of sodium chloride will form?

6. Law of Definite Proportions
A compound is always made of the same elements in the same proportion by mass, no matter the size of the sample.
% by Mass: ratio of each element to the total mass of the compound, shown as %.

7. Law of Definite Proportions
If 3.5g of element X reacts with 10.5g of element Y to form the compound XY, what is the % by mass of element X in the compound? % by mass of element Y?

8. Law of Definite Proportions
Two unknown compounds are tested. Compound I has 15.0g of H and 120.0g of O. Compound II has 2.0g of H and 32.0g of O. Are the compounds the same? Explain.