Download Notes/ws on limiting reactants and percent yield.

Chemistry
Worksheet : Stoichiometry : Notes/worksheet : obj. 20-22
Name :
Date :
A. Introduction to limiting reactants :
1. _____________________ reagents limit or determine the amount of product that will be produced.
2. _____________________ reagents have a quantity which is more than enough to react with a limiting reagent.
3. Identify the limiting reagent and the excess reagent for the following problem. You will need to write the
balanced equation first.
a. A high school chemistry student decides to make water by burning hydrogen in oxygen. He combines 2
moles of oxygen with 2 moles of hydrogen and ignites the mixture to form the water. Identify the limiting
and excess regents.
b. Determine the limiting reactant for the reaction between 8.4 moles of aluminum and 8.8 moles of oxygen
gas. The product is aluminum oxide.
c. Determine the limiting reactant for the reaction of 12.0 moles of HCl with 7.5 moles of zinc.
d. Determine the limiting reactant for the reaction between 12.0 grams of ethanol (C2H5OH), molar mass =
46.08g) and 10.0 L of oxygen gas (assume STP).
e. Determine the limiting reactant for the reaction between 20.0 g of iron(III) oxide and 5.0 g of lithium
metal.
4. Stoichiometry problems involving limiting reactants.
Solid sodium metal reacts with oxygen gas to form solid sodium oxide. What will occur when 2.50 moles of
sodium reacts with 4.50 moles of oxygen gas? Identify the limiting reagent and determine how many grams of
product is formed and how many grams of the excess reagent remains.
5. For the reaction above, how many grams of sodium oxide will be produced if 65.00 grams of sodium react with
100.00 grams of oxygen?
6. ________________________ yield is the calculated amount of product expected using the balanced equation.
7. _________________ yield is the amount of product produced when the reaction is carried out in the laboratory.
8. ___________________________ yield is the ratio of the actual yield to the theoretical yield times 100 percent.
9. Solid sodium bicarbonate decomposes when heated to form solid sodium carbonate, water and carbon dioxide
gas. What is the percent yield in this reaction if 80.00 g of sodium bicarbonate produces 37.51 g of sodium
carbonate?
10. In the Haber process nitrogen gas is combined with hydrogen gas to form ammonia (NH3). If 100.00 g of
nitrogen gas is combined with 21.00 grams of hydrogen gas and 105.809 g of ammonia gas is formed, what is
the percent yield?
11. Lime (CaO) is used to adjust the pH of acidic soils to make them more neutral. Lime is commercially
produced by the thermal decomposition of calcium carbonate into calcium oxide (lime) and carbon dioxide.
What is the percent yield when 1.35 kg of lime is produced from 2.50 kg of calcium carbonate?