Week 7 Practice Quiz - Mole Ratios, Limiting Reactants, Yield

What is a limiting reactant?

• the reactant that determines how much product can be made
• the reactant that is in excess
• the product that you can make the most of
• the amount of reactants that react with each other

You need 2 pieces of bread, 1 tablespoon of peanut butter and 2 tablespoons of jelly to make a sandwich.  If you have 10 pieces of bread, 4 tablespoons of peanut butter and 20 tablespoons of jelly, what is the limiting reactant?

• bread
• jelly
• peanut butter
• sandwich

Use the equation 2 Al + 3 Cl₂ ---> 2 AlCl₃.  If 2 moles of aluminum and 2 moles of chlorine are reacted, identify the limiting reactant.

• AlCl3
• Cl2
• Al

When does a chemical reaction stop?

• When the lab is finished
• When the excess reactant is used up
• When the limiting reactant is used up
• Chemical reactions never stop

Hydrogen and nitrogen react as shown to form ammonia (NH3). What is true of this reaction? 

• Three ammonia molecules are formed, with zero molecules remaining.

• Two ammonia molecules are formed, with two hydrogen molecules remaining.

• Six ammonia molecules are formed, with zero molecules remaining.

• Two ammonia molecules are formed, with two nitrogen molecules remaining. 

The diagram below represents H₂ and Cl₂ molecules that will potentially react to form HCl. Which of the following best describes this reaction?

• The limiting reactant is chlorine.

• The limiting reactant is hydrogen.

• Hydrogen and chlorine are nonreactive.

• All molecules shown will react to form the product. 

If a chemist calculates the maximum amount of product that could be obtained from a chemical reaction, he or she is calculating the

• Theoretical yield

• Mole ratio

• Actual yield

• Percentage yield

What is the measured amount of a product obtained from a chemical reaction?

• Mole ratio

• Theoretical yield

• Percentage yield

• Actual yield

What is the first thing you must do to solve a stoichiometry problem?

• Write a Balanced Equation
• Panic
• Write an Unbalanced Equation
• Avogadro's Number

What is the mole ratio of H₂O to H₃PO₄ in the following chemical equation?   P₄O₁₀ + 6 H₂O --> 4 H₃PO₄ 

• 6:4
• 4:6
• 1:3
• 3:1