 CHEM.B Apply the mole concept to representative particles (e.g., counting, determining mass of atoms, ions, molecules, and/or formula units).  CHEM.B Use stoichiometric relationships to calculate the amounts of reactants and products involved in a chemical reaction.  CHEM.B Describe the roles of limiting and excess reactants in chemical reactions.  CHEM.B Predict products of simple chemical reactions (e.g., synthesis, decomposition, single replacement, double replacement, combustion).

What is Stoichiometry? Section 12.1

 Define stoichiometry  Identify mole ratios in a balanced chemical equation

 Stoichiometry  Mole ratios

 Study of quantitative relationships between amounts of reactants used and products formed by a chemical reaction  Based on law of conservation of mass

 Ratio between number of moles of any 2 substances in a balanced chemical equation. 2Al + 3Br 2  2AlBr 3

Stoichiometric Calculations Section 12.2

 Identify and apply the steps to solving stoichiometry problems

1. Write a balanced chemical equation 2. Convert grams of known to mols of known 3. Convert mols of known to mols of unknown (using mole ratios) 4. Convert mols of unknown to grams of unknown

 25.0 g of NH 4 NO 3 produces N 2 O gas and H 2 O. Determine the mass of water produced. Known:Unknown: Mass of NH 4 NO 3 = 25.0 gMass of H 2 O = ?

1. Write the balanced chemical equation: NH 4 NO 3(s)  N 2 O (g) + 2H 2 O (g) 2. Convert grams of NH 4 NO 3 to mol using the molar mass: 25.0 g NH 4 NO 3 x 1 mol NH 4 NO 3 = mol NH 4 NO NH 4 NO 3 3. Determine the mole ratio of H2O to NH4NO3: 2 mol H 2 O 1 mol NH 4 NO 3 4. Multiply mol NH 4 NO 3 by the mole ratio: mol NH 4 NO 3 x 2 mol H 2 O = mol H 2 O 1 mol NH 4 NO 3 5. Calculate the mass of H 2 O using the molar mass: mol H 2 O x g H 2 O = 11.3 g H 2 O 1 mol H 2 O

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 Stoichiometry worksheet

Limiting Reactants Section 12.3

 Define limiting reactant  Solve stoichiometry problems that incorporate limiting reactants

 Limiting reactant: ◦ totally consumed during a chemical reaction ◦ limits the extent of the reaction ◦ determines the amount of product  Excess reactant: ◦ NOT completely consumed in reaction ◦ Some remains after the reaction stops (limiting reactant runs out)

1. Convert grams of each reactant to mols 2. Divide mols by stoichiometric coefficient 3. The smaller number is the LR 4. Use the LR to do stoichiometric calculations

S 8 + 4Cl 2  4S 2 Cl 2 If 200. g of S reacts with 100. g of Cl, what mass of S 2 Cl 2 is produced? 1. Convert both masses to moles: 200. g S 8 x 1 mol S 8 = mol S g S g Cl 2 x 1 mol Cl 2 = mol Cl g Cl 2

2. Divide mols by coefficient from the equation: mol Cl 2 = mol S 8 = mol Cl 2 1 mol S 8 3. The smaller one is the limiting reactant (Cl 2 )

4. Use the limiting reactant to determine the mass of S 2 Cl 2 as a stoichiometry problem from section 12.2: 100. g Cl 2 x 1 mol Cl 2 x 4 mol S 2 Cl 2 x g S 2 Cl g Cl 2 4 mol Cl 2 1 mol S 2 Cl 2 = 190. g S 2 Cl 2

The reaction between phosphorus and oxygen produced tetraphosphorus decaoxide. a. Determine the mass of P 4 O 10 formed if 25.0 g of P 4 and 50.0g of O 2 are combined. b. How much of the excess reactant remains after the reaction stops?

 Limiting Reactants Worksheet

Percent Yield Section 12.4

 Define theoretical, actual, and percent yield  Solve stoichiometry problems for percent yields

 Theoretical Yield: The maximum amount of product that can mathematically be produced  Actual Yield: The amount of product produced in an experiment  Percent Yield: The ratio of actual yield to theoretical yield

actual yield (from exp) x 100 theoretical yield (from calc)

 14.0 g aluminum hydroxide reacts with hydrochloric acid, producing aluminum chloride and water. If the actual yield of aluminum chloride from this tablet is 22.0 g, what is the percent yield?

 When 20.0 g copper wire is placed into a silver nitrate solution, a single replacement reaction occurs. If 60. g silver is actually recovered from the reaction, determine the percent yield of the reaction.

 Percent Yield Worksheet