4.5 Stoichiometry

Multiple Choice

Which of the following best explains the learning objective for stoichiometry?

• To memorize chemical formulas

• To explain changes in the amounts of reactants and products based on the balanced reaction equation

• To list all types of chemical reactions

• To describe the history of chemistry

Open Ended

Why is it important that no mass is lost or gained when a substance changes into a new substance during a chemical reaction?

Multiple Choice

What is the primary requirement before performing any stoichiometric calculations?

• Having a properly balanced chemical equation

• Knowing the molar mass of all substances

• Identifying the limiting reagent

• Measuring the temperature and pressure

Open Ended

Explain the steps you would take to solve a stoichiometry problem where you are given the mass of a reactant and asked to find the volume of a gas produced at STP.

Multiple Choice

Based on the stoichiometry map, which of the following can be directly converted to moles using Avogadro's Number?

• Mass

• Liters of Gas (at STP)

• Liters of Solution (Given Molarity)

• Particles

Multiple Choice

Which of the following best describes the limiting reagent in a chemical reaction?

• The reactant that produces the most product

• The reactant that is present in the greatest amount

• The reactant that runs out first and limits the amount of product formed

• The product that is formed in the smallest amount

Multiple Choice

When solving a limiting reagent problem, why is it necessary to compare the amount of product formed from each reactant?

• To determine which reactant is in excess

• To find the total yield of the reaction

• To identify the reactant that limits the amount of product formed

• To balance the chemical equation

Open Ended

Explain the difference between theoretical yield and actual yield in a chemical reaction. Why is it important to compare them?

Multiple Choice

If 21 grams of Fe2O3 is the theoretical yield but only 19.8 grams is obtained experimentally, what is the percent yield for this reaction?

• 94.3%

• 105.8%

• 85.2%

• 100%

Open Ended

How much excess reactant is left over when 50 mL of 0.250 M iron (III) chloride (FeCl3) is reacted with 50 mL of 0.250 M sodium carbonate (Na2CO3) solution?

Open Ended

Explain how the balanced reaction equation helps in determining the amounts of reactants and products in a chemical process.