Worksheet: Percentage Yield

In this worksheet, we will practice identifying the limiting reagent and calculating the percentage yield of desired products based on the actual and theoretical yield.

Q1:

Sodium nitrate was dissolved in water at 80C to produce a saturated solution. The solution was filtered to remove undissolved solid and then cooled to 0C to precipitate the sodium nitrate. The solubilities of sodium nitrate at 80 and 0C are 148 g/L and 73 g/L respectively. Calculate the percentage yield for this recrystallization method.

Q2:

Reaction of 1.274 g of aqueous copper sulfate with excess zinc metal produced 0.392 g of copper metal according to the equation shown. CuSO()+Zn()Cu()+ZnSO()44aqssaq

Calculate, to the nearest whole number, the percentage yield of this reaction.

Q3:

A student treated 15 g of copper(II) oxide with excess hydrochloric acid and purified the copper(II) chloride product by recrystallization. The final mass of pure copper(II) chloride was 11 g. What was the percentage yield?

Q4:

What is the formula for calculating the percentage yield from the actual yield and the theoretical yield?

  • APercentageyieldactualyieldtheoreticalyield=
  • BPercentageyieldtheoreticalyieldactualyield=×100%
  • CPercentageyieldtheoreticalyieldactualyield=
  • DPercentageyieldactualyield=×100%
  • EPercentageyieldactualyieldtheoreticalyield=×100%

Q5:

A student is electroplating an electrode using copper sulfate solution. Based on the current measured during the experiment, the electrode should be coated with 12.2 g of copper. However, the electrode is only coated with 10.4 g of copper. What is the percentage yield of the electroplating process?

Q6:

In an attempt to make calcium oxide, a student heats 100.0 g of calcium carbonate and weighs the remaining solid material. The final mass is 62.3 g. What is the percentage yield of calcium oxide?

Q7:

One mole of propane is burned using 7 moles of oxygen according to the following equation. CH+OHO+CO38222 By balancing the equation, identify the limiting reagent for this reaction.

  • ACH38
  • BO2
  • CNeither

Q8:

20 g of NaAlH4 reacts with 10 g of LiCl to produce 8.3 g of LiAlH4. NaAlH+LiClLiAlH+NaCl44 What is the percentage yield for this reaction?

Q9:

Sodium carbonate can be made using the Solvay process according to the following equation. 2NaCl+CaCONaCO+CaCl3232

If 29.25 g of sodium chloride is reacted with 50.00 g of calcium carbonate, what is the limiting reagent?

  • ACaCO3
  • BNaCl
  • CNeither

What mass of NaCl is needed to completely react with CaCO3? Give your answer to 1 decimal place.

Q10:

The combustion of methanol can be represented by the following chemical equation. 2CHOH+3O2CO+4HO3222 In which of the following molar ratios, between CHOH3 and O2, will there be an excess of oxygen?

  • A53
  • B32
  • C46
  • D21
  • E13

Q11:

In an industrial reaction, iron oxide reacts with carbon to make iron and carbon monoxide. FeO+4C3Fe+4CO34

Calculate the percentage yield if 2 kg of FeO34 produces 800 g of iron.

Q12:

Which of these is not a factor that may affect percentage yield?

  • AThe amount of gas produced
  • BThe reaction being reversible
  • CThe loss of product during separation or handling
  • DUnwanted products formed from side reactions
  • EThe purity of the reactants

Q13:

Anaerobic respiration converts glucose (CHO)6126 into ethanol and carbon dioxide according to the following equation. CHO2CHOH+2CO6126252

In one reaction, 405 g of ethanol was produced with a percentage yield of 88%. How much glucose was used at the start of this reaction? Give your answer in units of kilograms (kg) and to 1 decimal place.

Q14:

A metal chloride compound is reacted with hydrogen fluoride to make a metal fluoride and hydrogen chloride, as shown below. MCl+4HFMF+4HCl44

10 g of MCl4 produces 5.55 g of MF4 with a percentage yield of 85.1%. Identify the metal M from its calculated atomic mass.

  • AScandium
  • BManganese
  • CTitanium
  • DVanadium
  • EChromium

Q15:

0.75 moles of magnesium is reacted with an excess of sulfuric acid to make magnesium sulfate and hydrogen gas. Mg+HSOMgSO+H2442

What mass of MgSO4 is produced? Give your answer to the nearest whole number.

What would happen if the amount of magnesium was doubled and an excess of sulfuric acid was used?

  • AThe yield of MgSO4 will double.
  • BThe yield of MgSO4 will halve.
  • CThe yield of MgSO4 will quadruple.
  • DThe yield of MgSO4 will not change.
  • EThe yield of MgSO4 will drop to zero.

If 250 g of sulfuric acid was used, what would happen if the amount of magnesium used was quadrupled?

  • AMagnesium becomes the excess reagent.
  • BThe yield of MgSO4 will halve.
  • CThe yield of MgSO4 will quadruple.
  • DThe reaction will not occur.
  • EHSO24 remains the excess reagent.

Q16:

Which of the following is the best description for the term limiting reagent?

  • AThe reactant that gets used up first in a reaction
  • BThe reactant that is in excess
  • CThe reactant with the largest mass
  • DThe reactant that gets used up last in a reaction
  • EThe reactant that is most unstable

Q17:

Which of the following statements best describes the theoretical yield?

  • AThe theoretical yield is the same as the actual yield multiplied by 100.
  • BThe theoretical yield is the amount of product that could be obtained from a reaction if all the reactants are converted to form that product.
  • CThe theoretical yield is the amount of product that is obtained experimentally from the reaction.
  • DThe theoretical yield is the result of adding the percentage yield to the actual yield.

Q18:

A student isolated 25 g of a compound following a procedure that would theoretically yield 81 g. What was its percent yield? Give your answer to 1 decimal place.

Q19:

How many molecules of CHCl242 can be prepared from 15 CH24 molecules and 8 Cl2 molecules?

  • A8 molecules
  • B23 molecules
  • C15 molecules
  • D4 molecules

Q20:

Consider the given equation.

3Si()+2N()SiN()sgs234

What is the limiting reactant when 2.00 g of Si and 1.50 g of N2 react?

  • AN2
  • BSi
  • CBoth reactants are equal.

Q21:

Which of the following explains why a reaction yield may appear to be above 100%?

  • AThere are two or more reactions that occur simultaneously so that some reactants are converted to products.
  • BAll reactions are complete; therefore, all reactants are converted to products.
  • CThe reagents are of high purity.
  • DThe product of the reaction contains impurities.

Q22:

In a laboratory experiment, the reaction of 3 mol of H2 with 2 mol of I2 produced 1 mol of HI. Calculate the percent yield for this reaction.

Q23:

Consider the balanced equation shown.

CHO+6O6CO+3HO663222

If the reaction of 40.8 grams of CHO663 produces a 39% yield, how many grams of HO2 will be produced? Approximate your answer to one decimal place.

Q24:

A scientist performed an experiment to produce sodium sulfate. She expected to get 41.9 g of sodium sulfate but got 33.4 g instead. Calculate the percentage yield of this reaction to one decimal place.

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