1. Stoichiometry

2. The study of quantitative relationships between amounts of reactants used and products formed by a chemical reaction is called Stoichiometry. Stoichiometry is based on the law of conservation of mass, which was introduced by Antoine Lavoisier in the 18 th century Matter is not created or destroyed in a chemical reaction

3. _Fe + _O 2 → _Fe 2 O 3 4Fe + 3O 2 → 2Fe 2 O 3 4 mol Fe × 55.85g = 223.4 g of Fe 3 O 2 × 32.00g = 96.00 g of O 2 Total mass of reactants 319.4g 2 mol of Fe 2 O 3 × 159.7 g = 319.4 g Mass of products is the same as reactants: 319.4 g

4. We can derive several relationships from this balanced equation. Iron+Oxygen→Iron(III)Oxide 4Fe+3O 2 →2Fe 2 O 3 4 atoms Fe+3 molecules O 2 →2 F.U. 2Fe 2 O 3 4 Moles Fe+3 moles O 2 →2 moles 2Fe 2 O 3 223.4 g Fe+96.0 g O 2 →319.4 g 2Fe 2 O 3 319.4 g of Reactants→319.4g of Products

5. Coefficients in balanced chemical equations represent how many moles of each compound or element are present. Ex: 4Fe (s) + 3O 2 (g)  2Fe 2 O 3 (s) 4 moles Fe3 moles O 2 2 moles Fe 2 O 3

6. A mole ratio is a ratio between the numbers of moles of any two substances in a balanced chemical equation. 4Fe (s) + 3O 2 (g)  2Fe 2 O 3 (s) Examples of mole ratios: 4 mol Fe or 4 mol Fe or 3 mol O 2 3 mole O 2 2 mol Fe 2 O 3 2 mol Fe 2 O 3

7. Determine all possible mole ratios for the following equations: 4 Al + 3 O 2  2 Al 2 O 3 4 mol Al4 mol Al 3 mol O 2 2 mol Al 2 O 3 3 mol O 2 3 mol O 2 4 mol Al 2 mol Al 2 O 3 2 mol Al 2 O 3 2 mol Al 2 O 3 4 mol Al 3 mol O 2

11. If 5.50 moles of calcium carbide reacts with an excess of water, how many moles of acetylene will be produced? CaC 2 + H 2 O  Ca(OH) 2 + C 2 H 2

12. How many moles of carbon dioxide can be produced if one antacid tablet containing 0.0119 mol of NaHCO 3 is dissolved? NaHCO 3 + H 3 C 6 H 5 O 7  CO 2 + H 2 O + Na 3 C 6 H 5 O 7

14. Sodium chloride is decomposed into the elements sodium and chlorine. How many grams of chlorine has can be obtained from 2.50 moles NaCl?

16. If 6.77 grams of SO 2 react with excess oxygen and water, how many grams of H 2 SO 4 are produced? SO 2 + O 2 + H 2 O  H 2 SO 4

17. Chemical reactions stop when one of the reactants is used up. You have to use the right amount of reactants if you want a certain amount of products. Manufactures strive to have the right balances of chemicals to save cost and speed up production. It is all about the $$$$$

18. The limiting reactant stops the reactions because it runs out first. Gas + Car = miles…until you run out of gas Excess reactants are the reactants that are left over once the limiting reactant is used up.

21. Theoretical yield is the maximum amount of product that can be produced from the reactants Actual yield is the amount actually produced when the reaction occurs. Percent yield is the ratio of difference.