Limiting Reactants Practice Quiz

Which reactant is left over after a chemical reaction?

• Excess reactant

• Mole ratio

• Composition reactant

• Limiting reactant

What is the ratio of the actual mass to theoretical mass, multiplied by 100%?

• Mole ratio

• Percent Yield

• Avogadro yield

• Excess Yield

A chemist interested in the successfulness of a chemical reaction would calculate the

• Mole ratio

• Energy released

• Percent yield

• Rate of reaction

For the reaction SO₃ + H₂O → H₂SO₄, calculate the percent yield if 6142.5 grams of sulfuric acid is predicted to be produced but 575 grams is actually produced.

• 82.7%

• 88.3%

• 91.2%

• 93.9%

Hydrogen gas (H₂) combines with oxygen gas (O₂) according to the equation: 2H₂ + O₂ → 2H₂O. What is the limiting reactant if 4 moles of H₂ combines with 3.5 moles of O₂?

• O₂

• H₂

• H₂O

• O₂ and H₂

The actual amount of product obtained from a chemical reaction is the ______________ while calculated amount of product based on the starting amounts of reactants is the ___________________.

• Actual yield, percent yield

• Actual yield, theoretical yield

• Theoretical yield, actual yield

• Theoretical yield, percent yield

Micah conducts an experiment and determines the percentage yield of potassium suflate for the following reaction to be 300%: 2 KOH + H₂SO₄ → K₂SO₄ + 2 H₂O
He used 3 g of KOH (molar mass = 56.11 g/mol) and an excess of H₂SO₄. He determined the theoretical yield to be 0.963 grams and had an actual yield of 250.6 grams of K₂SO₄. The teacher tells him his answer is incorrect. What did Micah do wrong?

• He did not use a balanced equation.

• He used the mass of the water to determine the theoretical yield.

• He used the mass of excess reactant (HCl) to determine the theoretical yield.

• He determined the theoretical yield for the incorrect compound.

A students conducts a lab by mixing 5.0 grams of magnesium ribbon (Mg) wire with 25.0 grams of zinc nitrate (ZnNO₃) in the following balanced equation: Mg (s) + 2 ZnNO₃ (aq) → 2 Zn (s) + Mg(NO₃)₂ (aq). The student calculates the theoretical mass of silver produced in the reactions using the following equations:

5.0g Mg x (1 mol Mg / 24.3 g Mg) x (2 mol Zn / 1 mol Mg) x (65.38 g Zn / 1 mol Zn) = 26.9 g Zn

25.0 g ZnNO₃ x (1 mol ZnNO₃ / 127.39 g ZnNO₃) x (2 mol Zn / 2 mol ZnNO₃) x (65.38 g Zn / 1 mol Zn) = 12.8 g Zn

What is the limiting reactant?

• Mg

• ZnNO₃

• Zn

• Mg(NO₃)₂

A students conducts a lab by mixing 5.0 grams of magnesium ribbon (Mg) wire with 25.0 grams of zinc nitrate (ZnNO₃) in the following balanced equation: Mg (s) + 2 ZnNO₃ (aq) → 2 Zn (s) + Mg(NO₃)₂ (aq). The student calculates the theoretical mass of silver produced in the reactions using the following equations:

5.0g Mg x (1 mol Mg / 24.3 g Mg) x (2 mol Zn / 1 mol Mg) x (65.38 g Zn / 1 mol Zn) = 26.9 g Zn

25.0 g ZnNO₃ x (1 mol ZnNO₃ / 127.39 g ZnNO₃) x (2 mol Zn / 2 mol ZnNO₃) x (65.38 g Zn / 1 mol Zn) = 12.8 g Zn

What is the excess reactant?

• Mg

• ZnNO₃

• Zn

• Mg(NO₃)₂

A students conducts a lab by mixing 5.0 grams of magnesium ribbon (Mg) wire with 25.0 grams of zinc nitrate (ZnNO₃) in the following balanced equation: Mg (s) + 2 ZnNO₃ (aq) → 2 Zn (s) + Mg(NO₃)₂ (aq). The student calculates the theoretical mass of silver produced in the reactions using the following equations:

5.0g Mg x (1 mol Mg / 24.3 g Mg) x (2 mol Zn / 1 mol Mg) x (65.38 g Zn / 1 mol Zn) = 26.9 g Zn

25.0 g ZnNO₃ x (1 mol ZnNO₃ / 127.39 g ZnNO₃) x (2 mol Zn / 2 mol ZnNO₃) x (65.38 g Zn / 1 mol Zn) = 12.8 g Zn

What amount of Zn is produced?

• 5.0 g

• 25.0 g

• 26.9 g

• 12.8 g