Stoichiometry of Non-Limiting Reagents

1. In the thermite reaction, molten iron is produced from iron (III) oxide and aluminum metal according to the following UNBALANCED chemical equation:

Al (s) + Fe2O3 (s) → Al2O3 (s) + Fe (l) a. Balance the equation. b. Calculate the number of grams of aluminum and iron (III) oxide required to produce 1 kilogram of molten iron. c. How many grams of aluminum oxide would also be produced in this reaction?

2. In dilute nitric acid, HNO3, copper metal dissolves according to the following balanced chemical equation:

Cu (s) + HNO3 (aq) → Cu(NO3)2 (aq) + NO (g) + H2O (l) a. Balance the equation. b. How many grams of HNO3 are needed to dissolve 11.45 grams of copper metal? c. How many liters of nitrogen monoxide gas would be produced in this reaction?

3. Gaseous sulfur dioxide can be removed from smokestacks by treatment with limestone (CaCO3) and oxygen. The products in the reaction are calcium sulfate and carbon dioxide. a. Write a balanced equation for this reaction. b. What mass of calcium carbonate is required to remove 150 grams of sulfur dioxide? c. What mass of calcium sulfate is formed when 150 grams of sulfur dioxide is consumed completely?

4. Careful decomposition of ammonium nitrate produces laughing gas (N2O) and water. write a balanced equation for this reaction a. What masses of water can be obtained from the decomposition of 10.0 g of NH4NO3? b. How many liters of N2O is formed?

Stoichiometry of Limiting Reagents

1. Hydrazine (N2H4) reacts with dinitrogen tetraoxide to form nitrogen gas and water vapor. a. Write the balanced equation for the reaction b. Starting with 100 g of hydrazine and 200 g of dinitrogen tetraoxide, determine the limiting reactant. c. What is the theoretical yield of nitrogen gas? Of water vapor? d. What mass of the excess reactant remains when the limiting reactant is consumed?

2. In the combustion reaction of ammonia, gaseous water and nitrogen monoxide are formed.

NH3 + O2 → H2O + NO a. Balance the equation. b. If 20 g of NH3 are burned in 30 g of O2, how many grams of NO are formed? c. How many liters of total gas is formed?

3. In a single replacement reaction, aluminum metal reacts with hydrochloric acid to form aluminum chloride and hydrogen gas.

Al + HCl → AlCl3 + H2 a. Balance the equation. b. If 25 g of aluminum was added to 90 g of HCl, what mass of H2will be produced?

4. In the Haber process, ammonia is formed in the composition reaction of hydrogen and nitrogen gas.

N2 + H2 → NH3 a. Balance the equation. b. If you have 20 g of N2 and 5.0 g of H2, which is the limiting reagent? c. How many grams of ammonia can be formed by this reaction?

5. Aluminum oxide is formed from the combustion of aluminum. a. Write and balance the reaction. b. What mass of aluminum oxide is formed when 10.0 g of Al is burned in 20.0 g of O2?

6. When C3H8 burns in oxygen, CO2 and H2O are produced. a. Write the balanced reaction. b. If 15.0 g of C3H8 reacts with 60.0 g of O2, how many liters of CO2 are formed?

Percent Yield Problems

1. What is the % yield of NH3 if 40.5 g NH3 is produced from 20.0 mol H2 and excess N2?

2. The electrolysis of water forms H2and O2. 12.3 g of O2 is produced from the decomposition of 14.0 g H2O. a. Write and balance the reaction. b. What is the theoretical yield of O2? c. What is the percent yield? 3. Potassium chlorate decomposes upon heating to produce potassium chloride and oxygen gas. 2.107 g of oxygen is produced in the heating of 300 g of KClO3. a. Write and balance the reaction. b. Calculate the theoretical yield. c. Calculate the percent yield.

4. Methanol, CH3OH, is a clean-burning, easily handled fuel. It can be made by the direct reaction of CO and H2 as follows:

CO (g) + H2 (g) → CH3OH (l) a. Balance the reaction. b. Starting with a mixture of 12.0 g of H2 and 74.5 g of CO, which is the limiting reactant? c. What mass of the excess reactant remains after the reaction is complete? d. What is the theoretical yield of methanol? e. If 78.5 grams of methanol are collected at the end of the experiment, what is the percent yield?

5. Water is formed in the combustion of hydrogen gas. 60 g of oxygen and 7.0 g of hydrogen are burned, producing 58 g of water. a. Write and balance the reaction. b. What is the theoretical yield? c. What is the percent yield?

6. Iron pyrites (FeS2) reacts with oxygen according to the following equation:

FeS2 + O2 → Fe2O3 + SO2

300 g of iron pyrites is burned in 200 g of O2, and 143 grams of ferric oxide is produced. a. Balance the reaction. b. Calculate the theoretical yield of iron (III) oxide. c. Calculate the percent yield.