Chapter 9

Stoichiometry

Objectives

Define Stoichiometry.

Describe the importance of the mole ratio in stoichiometric calculations.

Write a mole ratio relating two substances in a chemical equation.

  1. Section 9.1 Introduction to Stoichiometry.
    1. Reaction-Stoichiometry problems
      1. Problem type 1: Given and unknown quantities are amount in moles.
      2. Problem type 2: Given is an amount in moles and the unknown is a mass that is often expressed in grams.
      3. Problem type 3: Given is a mass in grams and the unknown is an amount in moles.
      4. Problem types 4: Given is a mass in grams and the unknown is a mass in grams.
    2. Mole Ratio is a conversion factor that relates the amount in moles of any two substances involved in a chemical reaction.
    3. Molar Mass is the mass, in grams, of one mole of a substance.

    Objectives

    Calculate the amount in moles of a reactant or product from the amount in moles of a different reactant or product.

    Calculate the mass of a reactant or product from the amount in moles of a different reactant or product.

    Calculate the amount in moles of a reactant or product from the mass of a different reactant or product.

    Calculate the mass of a reactant or product from the mass of a different reactant or product.

  2. Section 9-2 Ideal Stoichioometric Calculations
    1. Conversions of Quantities in moles
      1. Page 281
      2. Practice
    2. Conversions of amounts in moles to mass
      1. Page 282
      2. Practice
    3. Conversions of mass to amount in moles
      1. Page 284
      2. Practice
    4. Mass-mass calculations
      1. Page 286
      2. Practice

     

    Objectives

    Describe a method for determining which of two reactants is a limiting reactant.

    Calculate the amount in moles or mass in grams of a product, given the amounts in moles or masses in grams of two reactants, one of which is in excess.

    Distinguish between theoretical yield, actual yield, and percent yield.

    Calculate percent yield, given the actual yield and quantity of a reactant.

  3. Section 9.3 Limiting Reactants and Percent Yield
    1. Limiting reactants- is the reactant that limits the amounts of the other reactants that can combine and the amount of product that can form in a chemical reaction.
    2. Excess reactant- the substance that is not used up completely in a reaction.
    3. What to do?
      1. Take one of the reactants and solve for the other
      2. If the solved amount is less than the given then the other given is the limiting reactant.
      3. The other reactant is the excess.
      4. Practice page 289
    4. What to do next?
      1. Using the limiting reactant solve for the unknown product.
      2. Subtract to find amount left over.
    5. Percent Yield
      1. Theoretical yield- is the maximum amount of product that can be produced form a given amount of reactants.
      2. Actual yield- the measured amount of a product obtained from a reaction.
      3. Percent yield- is a ratio of the actual yield to the theoretical yield, multiplied by 100
      4. Equation

        5. Percent yield= Actual yield X 100%

        Theoretical yield

      5. Practice page 293
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