http://www.ck12.org Chapter 12. Stoichiometry
12.3 Limiting Reactant and Percent Yield
Lesson Objectives
- Define limiting reagent, theoretical yield, and percent yield.
- Calculate theoretical yield for a given chemical process.
- Be able to determine which reactant is the limiting reactant, calculate the amount of product formed, and
determine the percent yield. - Use reaction tables to describe mass and mole changes for a given chemical reaction.
Lesson Vocabulary
- actual yield: The amount of product that is actually produced.
- theoretical yield: The maximum amount of product that can be generated from the given amounts of reactants.
- percent yield: Tells us what percentage of the possible amount of product (the theoretical yield) was actually
obtained (the actual yield). - excess reactant (excess reagent): When there is more reactant available than is required to react with the
other available reactants. Some amount of reactant will be leftover at the end of the reaction. - limiting reactant (limiting reagent): The reactant that is completely consumed in a reaction.
Check Your Understanding
Write the balanced chemical equations for the following reactions:
- Methane (CH 4 ) reacts with oxygen in the air to produce water and carbon dioxide.
- Solutions of barium chloride and sodium sulfate react to form a precipitate of barium sulfate and an aqueous
solution of sodium chloride. - Carbon monoxide reacts with oxygen to produce carbon dioxide.
Introduction
In the last lesson, we learned how to perform stoichiometry calculations, which relate masses and moles of reactants
and products for a given chemical process. In this lesson, we are going to compare theoretical yield (the maximum
amount that could be produced in a reaction) to actual yield (the amount that is actually produced). We will also
investigate what happens when one reactant runs out before the other reactants are fully consumed. Finally, we will
study how to express changes in masses and moles for a given chemical process using the reaction table method.