II. Stoichiometry in the Real World Stoichiometry – Unit. 10

Stoichiometry – Quantitative measurements between Reactants used and Products formed in chemical reaction (Law of Conservation of Mass)

Do Now b Victoria Sandwich Cake recipe: b 1 cup of Self Rising Flour b ½ cup of Sugar b ½ cup of Margarine b 1tsp of baking powder b 4 eggs What is the ratio of flour to sugar? What is the ratio of baking powder to Margarine?

Relationship derived from a balanced Equation b Iron + Oxygen Iron (III) Oxide b 4Fe + 3O 2 2Fe 2 O 3 4 molsFe 3 mols O 2 2 mols Fe 2 O 3 223g/mol 93g/mol 319.4g/mol

Example:Example: b C 3 H 8 (aq) + O 2(aq) CO 2 + H 2 O b = C. Johannesson

A. Limiting Reactants b Available Ingredients 1 pack of Hot dogs rolls (8rolls) 1 pack of Hot dogs (6 dogs) b Limiting Reactant ? b Excess Reactants ?

A. Limiting Reactants b Limiting Reactant used up in a reaction determines the amount of product b Excess Reactant added to ensure that the other reactant is completely used up cheaper & easier to recycle

A. Limiting Reactants 1. Write a balanced equation. 2. For each reactant, calculate the amount of product formed. 3. Smaller answer indicates: limiting reactant amount of product

Calculating the Amount of Product b Grams Convert Mole Ratio Convert Product(Grams) (GIVEN ) to Moles to Grams(ASKED)

A. Limiting Reactants b 79.1 g of zinc react with 0.90 L of 2.5M HCl. Identify the limiting and excess reactants. How many liters of hydrogen are formed at STP? Zn + 2HCl  ZnCl 2 + H g ? L 0.90 L 2.5M

A. Limiting Reactants 79.1 g Zn 1 mol Zn g Zn = 27.1 L H 2 1 mol H 2 1 mol Zn 22.4 L H 2 1 mol H 2 Zn + 2HCl  ZnCl 2 + H g ? L 0.90 L 2.5M

A. Limiting Reactants 22.4 L H 2 1 mol H L 2.5 mol HCl 1 L = 25 L H 2 1 mol H 2 2 mol HCl Zn + 2HCl  ZnCl 2 + H g ? L 0.90 L 2.5M

C. Johannesson A. Limiting Reactants Zn: 27.1 L H 2 HCl: 25 L H 2 Limiting reactant: HCl Excess reactant: Zn Product Formed: 25 L H 2 left over zinc

B. Percent Yield calculated on paper measured in lab

B. Percent Yield b When 45.8 g of K 2 CO 3 react with excess HCl, 46.3 g of KCl are formed. Calculate the theoretical and % yields of KCl. K 2 CO 3 + 2HCl  2KCl + H 2 O + CO g? g actual: 46.3 g

B. Percent Yield 45.8 g K 2 CO 3 1 mol K 2 CO g K 2 CO 3 = 49.4 g KCl 2 mol KCl 1 mol K 2 CO g KCl 1 mol KCl K 2 CO 3 + 2HCl  2KCl + H 2 O + CO g? g actual: 46.3 g Theoretical Yield:

B. Percent Yield Theoretical Yield = 49.4 g KCl % Yield = 46.3 g 49.4 g  100 = 93.7% K 2 CO 3 + 2HCl  2KCl + H 2 O + CO g49.4 g actual: 46.3 g