Worksheet: Maximum and Percentage Yields

In this worksheet, we will practice calculating the percentage yield of a reaction from the chemical equation and the mass or concentration of product.

Q1:

A student produces solid potassium chloride and oxygen gas via the thermal decomposition of 53.2 g of solid potassium chlorate (KClO3). The mass of the remaining solid material is 38.5 g.

Calculate the number of moles of potassium chloride produced.

Calculate the percentage yield of this reaction.

Q2:

When potassium iodide reacts with lead(II) nitrate, a yellow precipitate (PbI)2 is produced. If 0.78 g of lead(II) iodide was produced, how many grams of lead(II) nitrate was used? You may assume that the reaction yield was 100% and that an excess of potassium iodide was used.

Q3:

A freshly cut piece of strontium metal is left to oxidize completely in dry air. Its final mass is 5.95 g. What was the mass of the strontium metal?

Q4:

After weighing the solid product of their reaction, a student finds that their calculated yield is over 100%. Which of the following is not a potential cause?

  • AThe balance was not properly tared.
  • BThe product has not been completely dried.
  • CThe reaction generated other solid products.
  • DThe molar mass of the product is lower than calculated.
  • EThe reactant was not accurately weighed.

Q5:

White phosphorus (P)4 is oxidized by oxygen gas to phosphorus pentoxide (PO)410 with no by-products. Calculate the percentage yield if 8.30 g of phosphorus pentoxide is obtained from the reaction of 40.0 mmol of white phosphorus with 240 mmol of oxygen gas.

Q6:

Ether (CHO)410 is prepared from ethanol by an acid-catalyzed condensation reaction, with water as the only by-product. The densities of ether and ethanol are 0.7134 g/mL and 0.7894 g/mL respectively. Calculate the percentage yield of a reaction that produces 1.17 L of ether from 1.500 L of ethanol.

Q7:

Toluene (CHCH)653 can be oxidized by air to benzoic acid (CHCOOH)65, with water as the only by-product. Calculate the percentage yield for a reaction that converts 1.00 kg of toluene to 1.21 kg of benzoic acid.

Q8:

Citric acid (CHO)687 is prepared via the fermentation of sucrose. This process is represented by the chemical equation shown. CHO+3O2CHO+3HO12221126872 Calculate the mass of citric acid obtained from 2.50 metric tons of sucrose if the yield is 85.30%.

Q9:

How many molecules of 1,1,2,2-tetrachloroethane can be prepared from 13 molecules of ethane and 21 molecules of Cl2?

Q10:

Uranyl nitrate (UO(NO)232) can be precipitated from acidic solution by reaction with sodium oxalate (NaCO224), as shown. UO(NO)()+NaCO()+3HO()UO(CO)·3HO()+2NaNO()232224222423aqaqlsaq Addition of 0.4031 g of sodium oxalate to a solution containing 1.481 g of uranyl nitrate yields 1.073 g of UO(CO)·3HO2242. Calculate to 3 significant figures the percentage yield for this reaction.

Q11:

Chromium and phosphoric acid react according to the equation shown. 2Cr()+2HPO()2CrPO()+3H()slsg3442 Calculate the percentage yield if 0.50 mol of chromium and 0.75 mol of phosphoric acid react to produce 62.1 g of chromium(III) phosphate.

Q12:

Urea can be synthesized by reacting carbon dioxide with gaseous ammonia, as shown. CO()+2NH()CO(NH)()+HO()23222ggsl Carbon dioxide is produced by complete combustion of carbon in excess oxygen. What is the maximum mass of urea that can be produced from 1.00 metric ton of carbon?

Q13:

Hydrogen chloride gas is produced by reacting 13.8 g of sodium chloride with excess sulfuric acid, as shown. NaCl()+HSO()HCl()+NaHSO()slgs244 What volume of 0.530 M hydrochloric acid can be prepared by dissolving this gas in water?

Q14:

Freon-12 (CClF)22 is prepared from carbon tetrachloride by reaction with hydrogen fluoride. The other product of this reaction is hydrogen chloride. Calculate the percentage yield, to two significant figures, for a reaction that yields 12.5 g of Freon-12 from 32.9 g of carbon tetrachloride.

Q15:

A sample of 0.56 g of carbon dioxide was obtained by heating 1.25 g of magnesium carbonate. Calculate the percentage yield for this reaction.

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