If you can do Dimensional Analysis, you can do stoichiometry 640 Tricycles are made each week How many wheels must be made? Given: 640 Tricycles 640 Tricycles 1Tricycle 3 Wheels =1920 Wheels 3 : 1 Ratio Unknown: # of wheels

Cookie Recipe 1 cup butter 1/2 cup white sugar 1 cup packed brown sugar 1 teaspoon vanilla extract 2 eggs 2 1/2 cups all-purpose flour 1 teaspoon salt 2 cups semisweet chocolate chips Makes 3 dozen How many cups of white sugar is needed if I had 1.5 cups flour? 1.5 cups flour 2.5 cups flour. 5 cup white sugar = 0.3 cups sugar

Like a cookie recipe, chemists use recipes too Instead of calling them recipes, we call them reaction equations Instead of using cups and teaspoons, we use moles Instead of eggs, butter, sugar, etc. we use chemical compounds as ingredients

Ratio (fraction) that compares moles of one substance to moles of another substance 2 moles H 1 mole H CO 2 3 H 2 0 Starting Compound Target Compound 2 moles NaCl 1 mole Na 2 CO 3

Use a balanced chemical equation Consider the combustion of propane: C 3 H O 2  3CO 2 + 4H 2 O 1 mole of proprane reacts with 5 moles of oxygen to produce 3 moles of carbon dioxide and 4 moles of water Possible Mole Ratios: 1 mol C 3 H 8 3 mol CO 2 5 mol O 2 4 mol H mol CO 2 5 mol O 2

How many moles of KClO 3 must decompose in order to produce 9 moles of oxygen gas? Step 1: Balance the chemical equation Step 2: Use mole ratio as conversion factor 2KClO 3  2KCl + 3O 2 = 6 mol KClO 3 9 mol O 2 3 mol O 2 2 mol KClO 3 Unit you “want” goes on top

How many moles of sodium chloride will be produced if you react 2.6 moles of chlorine gas with sodium metal? 2Na + Cl 2  2NaCl 2.6 mol Cl 2 1 mol Cl 2 2 mol NaCl

1 mol of a gas =22.4 L at STP S tandard T emperature & P ressure 0°C and 1 atm

Nitrogen Monoxide and Oxygen gas combine to form the brown gas nitrogen dioxide, which contributes to petrochemical smog. How many liters of nitrogen dioxide are produced when 34 liters of oxygen reacts with nitrogen monoxide. Assume conditions of STP Step 1: Balance the equation 2NO + O 2  2NO 2

34 L O L O 2 1 mol O 2 2 mol NO 2 1 mol NO L NO 2

7.5 mol Fe 2 O 3 1 mol Fe 2 O 3 3 mol CO 2 1 mol CO L CO 2