Unit 5: Stoichiometry Stoichiometry

Chemical Equations and the Mole Remember: a chemical equation is like a recipe – it tells you the ingredients (reactants) you need to make certain products chemical equations tell you the relative quantities of reactants and products in a reaction

Chemical Equations and the Mole How many moles do you have of each of the following? Frame (F): Seat (S): Wheel (W): Handlebar (H): Pedal (P): Tricycle (FSW3HP2): 1 mole 3 moles 2 moles

Chemical Equations and the Mole Example: If you had 4 moles of S and an excess of all the other reactants, how many tricycles (FSW3HP2) could you make? We can apply the tricycle example to chemical reactions.

Stoichiometry Stoichiometry: Using a known amount of one substance to predict how much of a reactant will be used or how much of a product will be produced. You can use stoichiometry to answer questions like: Calculate the number of grams of NH3 produced by the reaction of 5.40 g of nitrogen with an excess of hydrogen. N2 + H2 → NH3

Stoichiometry – The Box Method Calculate the number of grams of NH3 produced by the reaction of 5.40 g of nitrogen with an excess of hydrogen. N2 + H2 → NH3 Step 1: Balance the equation.

Stoichiometry – The Box Method Calculate the number of grams of NH3 produced by the reaction of 5.40 g of nitrogen with an excess of hydrogen. N2 + 3H2 → 2NH3 grams 5.40 g * molar mass 28.02 g/mol 17.034 g/mol moles Step 2: Construct the box and fill in known information (starting amount and molar masses).

Stoichiometry – The Box Method Calculate the number of grams of NH3 produced by the reaction of 5.40 g of nitrogen with an excess of hydrogen. N2 + 3H2 → 2NH3 grams 5.40 g *6.54 g molar mass 28.02 g/mol 17.034 g/mol moles 0.192 mol 0.384 mol MORE x 2/1 Step 3: Calculate missing information until you determine what the problem is asking you to find.

Stoichiometry – The Box Method Calculate the number of grams of NH3 produced by the reaction of 5.40 g of nitrogen with an excess of hydrogen. N2 + 3H2 → 2NH3 grams 5.40 g *6.54 g molar mass 28.02 g/mol 17.034 g/mol moles 0.192 mol 0.384 mol MORE x 2/1 Step 3: Calculate missing information until you determine what the problem is asking you to find.

Stoichiometry – Practice #1 How many grams of water would be produced from 60 grams of H2 and an excess of O2? __H2 + __O2 → __H2O

Stoichiometry – Practice #2 How many grams of water would be produced from 60 grams of H2 and an excess of O2? __CH4 + __O2 → +