CK-12-Chemistry Intermediate

12.3. Limiting Reactant and Percent Yield http://www.ck12.org

a. Determine the limiting reactant.

b. How many grams of the excess reactant remains after the reaction is complete?

c. What is the theoretical yield of each of the two products?

d. The reaction is performed and 16.2 g of N 2 F 4 is produced. Calculate the percent yield for the reaction.

7. 26.3 g of potassium metal reacts with 4.89 L of oxygen gas at STP, forming potassium oxide. 4K(s) + O 2 (g)
   →2K 2 O(s)
   a. Determine the limiting reactant.
   b. How much of the excess reactant remains after the reaction is complete? If the excess reactant is oxygen,
   give its volume.
   c. What mass of potassium oxide could theoretically be produced?


8. The percentage yield for the reaction of PCl 3 with Cl 2 to form PCl 5 is 80.8%. What mass of PCl 5 would be
   produced by the reaction of 37.8 g of PCl 3 with excess Cl 2? PCl 3 (g) + Cl 2 (g)→PCl 5 (g)


9. If 26.7 g of nickel metal is reacted with 178 g of silver nitrate, what mass of silver metal will be produced?
   What is the limiting reactant? Ni(s) + 2AgNO 3 (aq)→Ni(NO 3 ) 2 (aq) + 2Ag(s)


10. The Ostwald Process is a series of three reactions (shown below) that produces nitric acid from ammonia.
    1.00 kg of ammonia is subjected to the reactions, and unlimited amounts of oxygen and water are available. If
    each reaction proceeds at a 92.5% yield, what mass of HNO 3 is produced? Assume that any NO produced by
    the third reaction is lost and not reused as a reactant in the second reaction.

4NH 3 (g)+5O 2 (g)→4NO(g)+6H 2 O(g)

2NO(g)+O 2 (g)→2NO 2 (g)

3NO 2 (g)+H 2 O(g)→2HNO 3 (aq)+NO(g)

Further Reading / Supplemental Links

• TheLimitingReagentinChemicalReactions, (http://www.wisc-online.com/objects/ViewObject.aspx?ID=GCH7404


• ProductYieldsinChemicalReactions, (http://www.wisc-online.com/objects/ViewObject.aspx?ID=GCH7504


• TheChemCollective–StoichiometryTutorials–LimitingReagents, (http://www.chemcollective.org/stoich/limiting-
  reagents.php


• TheChemCollective–StoichiometryTutorials–ProductFormation, (http://www.chemcollective.org/stoich/percentyield.php


• You can use stoichiometry to determine empirical and molecular formula of an unidentified reactant. This
  combines skills from this section and the section on empirical and molecular formulas. Watch an example
  at http://www.khanacademy.org/science/physics/thermodynamics/v/empirical-and-molecular-formulas-from-
  stoichiometry.


• Another example of using stoichiometry to determine the empirical and molecular formula of an unidenti-
  fied reactant is at http://www.khanacademy.org/science/physics/thermodynamics/v/example-of-finding-react
  ant-empirical-formula.

Points to Consider

Now that you have an understanding of the quantitative relationships that exist between chemical substances in
chemical reactions, we will turn our attention to the states of matter and their relationships to one another.

• What are the three states of matter?


• How can changes in temperature and pressure affect the state of a sample of matter?