Limiting Reactant & % Yield Problems



Limiting Reactant & % Yield Problems

1. The ethanol used in Lily’s car could be made from the hydrocarbon ethylene (C2H4). Ethylene, a gas at room temperature, also burns with oxygen. Suppose we mix 0.25 mol C2H4 with 1.0 mol O2. Identify the limiting reactant and the number of moles of CO2 that can be formed.

2. In the double-displacement reaction of aqueous silver nitrate and magnesium chloride, silver chloride precipitates and aqueous magnesium nitrate forms. Suppose we mix 1.0 mol of silver nitrate with 1.0 mol of magnesium chloride. Identify the limiting reactant and the number of moles of solid AgCl that can form.

3. Sodium carbonate reacts with hydrochloric acid to produce aqueous sodium chloride, water and carbon dioxide gas. Determine the limiting reactant and mass of CO2 gas produced when 11.0 grams of Na2CO3 is added to a solution that contains 11.0 grams of HCl.

4. Sodium metal reacts with water in a single replacement reaction to produce aqueous sodium hydroxide and hydrogen gas. When 0.50 moles of Na is placed in water, all the sodium reacts, and the hydrogen gas produced is isolated. It is determined that 0.21 moles of H2 has been produced. What is the percent yield of H2?

5. Toxic carbon monoxide is a by-product of the preparation of hydrogen fuel from methanol for use in hydrogen-powered vehicles. When carbon monoxide reacts with oxygen gas, the greenhouse gas carbon dioxide is produced. When 5.0 mol CO is mixed with excess O2, the reaction occurs to give 3.4 mol CO2. What is the percent yield of the CO2?

6. What is the limiting reactant when 0.25 moles of P4 reacts with 0.75 mol O2 in the preparation of solid tetraphosphorus decaoxide.

7. Tetraphosphorus trisulfide is used in the heads of wooden matches. This material is manufactured by the heating of a mixture of red phosphorus (P4) and sulfur (S8). What is the limiting reactant when 0.20 mol P4 reacts with 0.10 mol S8?

8. Nitrogen reacts with hydrogen to form gaseous ammonia.

a. What is the limiting reactant if 10.0 grams of nitrogen reacts with 10.0 grams of hydrogen?

b. What is the maximum amount of NH3, in grams, that can be produced?

9. Sodium metal and chlorine gas react to form sodium chloride. If 5.00 grams of sodium metal reacts with excess chlorine gas, and 11.5 g NaCl is actually obtained, what is the percent yield of the NaCl?

10. Ammonia is synthesized commercially from nitrogen gas and hydrogen gas for the production of fertilizers. If 100.0 g of nitrogen is reacted with excess hydrogen, and 34.0 g of NH3 are obtained, what is the percent yield of ammonia?

11. When I2 is mixed with excess H2, 0.80 mol HI is isolated in the laboratory. If this reaction occurs to give an 85% yield, how many moles of I2 reacted?

12. Lithium metal will react violently in water to form lithium hydroxide and hydrogen gas. When Li is mixed with excess water, 0.30 mol H2 gas is isolated in the laboratory. If this reaction occurs to give an 85% yield of H2, how many moles of Li reacted?

13. Magnesium metal reacts with bromine to form liquid magnesium bromide. If 1.0 mol of Mg is mixed with 2.0 mol of Br2, and 0.84 mol of MgBr2 is obtained, what is the percent yield for the reaction?

14. Sodium metal reacts with nitrogen gas to produce solid sodium nitride. If 0.30 mol Na is mixed with 0.60 mol N2, and 0.092 mol Na3N is obtained, what is the percent yield for the reaction?

15. Liquid methyl salicylate (oil of wintergreen, C8H8O3) and water are products when salicylic acid (C7H6O3) is heated with methanol (CH3OH). In an experiment 1.50 grams of salicylic acid is reacted with 11.20 grams of methanol. The yield of oil of wintergreen is 1.24 grams. What is the % yield?

16. Hydrogen cyanide gas is prepared from ammonia, oxygen and natural gas, CH4, reacting together. The other product is water. If a reaction vessel contains 11.5 g NH3, 10.0 g O2 and 10.5 g CH4, what is the maximum mass of hydrogen cyanide that can be made?

17. Carbon disulfide burns in oxygen to produce carbon dioxide and sulfur dioxide. Calculate the grams of sulfur dioxide produced when a mixture of 15.0 grams of carbon disulfide and 35.0 g O2 reacts.

18. Acetic acid and aspirin, (acetylsalicylic acid, C9H8O4), are produced by heating salicylic acid (C7H6O3) with acetic anhydride (C4H6O3).

a. What is the theoretical yield of aspirin when 2.00 g of C7H6O3 is heated with 4.00 g of C4H6O3?

b. If the actual yield is 2.21 grams of aspirin, what is the percentage yield?

19. Titanium, which is used to make airplane engines and frames, can be obtained from titanium tetrachloride, which in turn is obtained from titanium dioxide by the following process: 2TiO2(s) + 3C(s) + 4Cl2(g)(2TiCl4(g) + CO2(g) + 2CO(g) A vessel contains 4.15 g titanium dioxide, 5.67 g of carbon, and 6.78 g of chlorine. Suppose the reaction goes to completion as written.

a. How many grams of titanium tetrachloride can be produced?

b. What is the percent yield if 8.0 grams have been produced?

20. Hydrogen chloride can be prepared in the laboratory by heating sodium chloride with concentrated sulfuric acid. A reaction vessel contains 10.0 g of sodium chloride and 10.0 g of sulfuric acid. What is the percent yield if 3.9 grams of hydrogen chloride are actually produced?

21. Large quantities of ammonia are burned in the presence of a platinum catalyst to produce nitrogen monoxide and water vapor. How many moles of nitrogen monoxide can be produced from 0.120 moles of ammonia and 0.140 moles of oxygen reacting together?

22. Potassium superoxide, KO2, reacts with water to generate oxygen for use in gas masks. If a reaction vessel contains 0.15 mol potassium superoxide and 1.8 grams of water,

a. How many moles of oxygen can be produced? (The other product is potassium hydroxide).

b. What is the percent yield if 0.09 moles of O2 are produced?

23. In an experiment 10.0 grams of butyric acid (C4H8O2) is heated with 3.14 grams of ethanol (C2H6O) to produce ethyl butyrate (C6H12O2) and water.

a. What is the theoretical yield of ethyl butyrate?

b. If the actual yield of ethyl butyrate is 5.3 grams, what is the percentage yield?

24. Hydrogen chloride and carbon monoxide can be prepared by burning methane (CH4) in chlorine and air. A reaction vessel contains 23.0 g methane, 65.0 g Cl2, and 50.0 g O2. What is the % yield of hydrogen chloride if 60. g were actually produced?

25. Aluminum chloride is used as a catalyst in various industrial reactions. It, along with hydrogen gas, is prepared from hydrogen chloride gas and aluminum metal shavings. Suppose a reaction vessel contains 0.15 mol Al and 0.35 mol HCl.

a. How many moles of aluminum chloride are produced?

b. What is the percent yield if 0.071 mols are actually produced?

26. Zinc metal reacts with hydrochloric acid in a single replacement reaction.

a. If 0.30 mol zinc are added to 20.0 g HCl(aq), how many moles of hydrogen are produced?

b. If 0.25 moles of hydrogen are actually produced, what is the percent yield?

27. Calcium chloride and silver nitrate undergo a double replacement reaction to produce silver chloride and calcium nitrate. How much silver chloride and calcium nitrate should be produced if 100.0 g AgNO3 reacts with 45 g CaCl?

28. Carbon dioxide is formed when there is enough oxygen present to react with carbon. If there isn’t enough oxygen, carbon monoxide forms. In a reaction vessel there are 50.0 g O2 and 25 g C.

a. Is this an adequate amount of oxygen? IF so, by how much in excess is the oxygen?

b. If not, by how much is the carbon in excess?

29. Sulfuric acid will react with barium hydroxide in a neutralization reaction. If 120.0 grams of sulfuric acid is combined with 230.0 grams of barium hydroxide,

a. Which reactant is in excess and by how much?

b. How much barium sulfate can theoretically be produced?

30. Calcium sulfate, carbon dioxide and water are produced when 100.0 grams of sulfuric acid reacts with 100.0 grams of calcium carbonate.

a. How much calcium sulfate can be produced?

b. What is the percent yield if only 125 grams are collected?

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