Stoichiometry Test

A student determines that the theoretical yield of CaCO3 from a precipitation reaction is 21.5 grams. However, this student only recovers 19.9 grams of precipitate through filtration of the solution. What would be this student’s percent yield?

• 85.6%

• 92.6%

• 108%

• 0.93%

The reaction for the decomposition of ammonia (NH3) can be written as shown. If a student starts with 21.7 g of NH3 how many grams of hydrogen gas (H2) will be produced by the reaction?

• 1.28 grams

• 32.5 grams

• 3.85 grams

• 2.55 grams

Iron reacts with oxygen to form iron (III) oxide according to the above reaction. During a classroom demonstration, 60.0 grams of iron are allowed to react with 30.0 grams of oxygen gas. What is the limiting reagent for this reaction, and what is the theoretical yield for iron (III) oxide?

• Iron is the limiting reagent producing 106 g of Fe2O3

• Oxygen is the limiting reagent producing 99.8 g of Fe2O3

• Oxygen is the limiting reagent producing 82.6 g of Fe2O3

• Iron is the limiting reagent producing 85.8 g of Fe2O3

Lithium reacts with nitrogen to form lithium nitride according to reaction shown above. During an experiment, 26.2 grams of nitrogen gas were reacted with an excess of lithium metal. What is the percent yield of this reaction if 50.7 grams of lithium nitride were recovered?

• 77.8%

• 51.7%

• 65.4%

• 70.5%

Phosphoric acid, H3PO4, is neutralized by magnesium hydroxide according to the equation shown. How many moles of water will be produced from the neutralization of 0.24 mole of H3PO4?

• 1.44 mol

• 0.24 mol

• 0.48 mol

• 0.72 mol

During an experiment, the reaction shown above was performed and allowed to go to completion. If 125 grams of potassium hydroxide were completely reacted, how many grams of potassium sulfate were produced?

• 194 g

• 206 g

• 177 g

• 184 g

The theoretical yield of a reaction is 82.5 grams, but the reaction actually yields 12.3 grams less than expected. What is the percent yield for this reaction?

• 67.1%

• 85.1%

• 14.9%

• 118%

When copper reacts with silver nitrate according to the equation, the number of grams of copper required to produce 432 grams of silver is —

• 31.5 g

• 127 g

• 216 g

• 252 g

A student performed a precipitation reaction and recorded the data shown in the table above. If the theoretical yield for the precipitate was 5.87 grams, what is the percent yield of this reaction based on the data?

• 95.2%

• 1.05%

• 82.8%

• 5.59%

How many moles of H₂ gas would be used to fill a 45.0 L tank at STP?

• 1 mole

• 22.4 L

• 2 moles

• 1008