Skills Worksheet Concept Review Section: Calculating Quantities in Reactions Complete each statement below by writing the correct term or phrase. 1. All stoichiometric calculations involving equations use ratios. 2. When solving stoichiometric problems, you must the equation first. 3. Balanced equations give the numbers of moles of substances. 4. in chemical equations provide mole ratios that can be used as conversion factors. 5. The conversion factor for converting between mass and moles is the of the substance. 6. In making calculations involving, you must convert volume to mass. 7. To convert from volume to mass, you can use the of the substance as the conversion factor. 8. When calculating the number of particles, you can use as the conversion factor. In the blanks at the left, write the letter of the choice that best completes the statement or answers the question. Consider the following problem when answering: What mass of sulfuric acid is required to neutralize 2.65 g of potassium hydroxide? The products of the reaction are potassium sulfate and water. 9. What should you do first after reading the problem carefully? a. Estimate the answer. b. Calculate the molar mass of sulfuric acid. c. Write a balanced chemical equation. d. Convert all masses to moles. 10. What should you do before setting up the problem? a. Determine the densities. b. Calculate molar masses. c. Convert all masses to moles. d. Estimate the answer. Holt Chemistry 1 Stoichiometry
11. How should you check your setup? a. by recalculating molar masses b. by checking to see if the result will have the correct units c. by estimating the answer d. by writing a balanced chemical equation 12. What should you round off? a. the result of each step b. all data values c. only the final answer d. nothing 13. Which of the following is least likely to help you verify the final result? a. estimating the answer by using rounded numbers b. determining whether the answer is reasonable for the conditions of the problem c. rechecking all molar masses d. writing a balanced chemical equation Answer the following items in the space provided. 14. Determine the number of grams of phosphorus formed for each 1.00 g of Ca 3 (PO 4 ) 2 used in the production of phosphorus in an electric furnace. Ca 3 (PO 4 ) 2 (s) 3SiO 2 (s) 5C(s) 3CaSiO 3 (s) 5CO(g) 2P(s) 15. How many grams of aluminum chloride are produced when 18 g of aluminum are reacted with an excess of hydrochloric acid? 2Al(s) 6HCl(aq) 2AlCl 3 (aq) + 3H 2 (g) Holt Chemistry 2 Stoichiometry
16. How many grams of ethanol, C 2 H 5 OH, can be made by the fermentation of 1150 g of glucose, C 6 H 12 O 6? C 6 H 12 O 6 (l) 2C 2 H 5 OH(l) 2CO 2 (g) 17. How many moles of oxygen are required for the combustion of 25.5 g of magnesium? 2Mg(s) O 2 (g) 2MgO(s) 18. How many grams of CO 2 are produced from the burning of 1.0 mol of amyl alcohol? 2C 5 H 11 OH(l) 15O 2 (g) 10CO 2 (g) 12H 2 O(g) 19. How many moles of nitromethane are needed to form 500.0 g of chloropicrin, CCl 3 NO 2, a chemical used in the production of insecticides? CH 3 NO 2 (l) 3Cl 2 (g) CCl 3 NO 2 (l) 3HCl(g) Holt Chemistry 3 Stoichiometry
20. How many liters of oxygen are produced from the decomposition of 122 g of potassium chlorate? The density of oxygen is 1.33 g/l. 2KClO 3 (s) 2KCl(s) 3O 2 (g) 21. How many grams of potassium chloride are formed by the decomposition of sufficient potassium chlorate to yield 3.4 L of oxygen? Remember that the density of oxygen is 1.33 g/l. 2KClO 3 (s) 2KCl(s) 3O 2 (g) 22. How many liters of phosphine gas are produced when 910 g of calcium phosphide react with water? The density of phosphine gas is 1.517 g/l. Ca 3 P 2 (s) 6H 2 O(l) 3Ca(OH) 2 (s) 2PH 3 (g) 23. How many grams of air are required to complete the combustion of 93 g of phosphorus to diphosphorus pentoxide, assuming the air to be 23% oxygen by mass? 4P(s) 5O 2 (g) 2P 2 O 5 (s) Holt Chemistry 4 Stoichiometry
24. How many metric tons of carbon dioxide can be produced from the combustion of 5.00 metric tons of coke that is 85.5% carbon? C(s) O 2 (g) CO 2 (g) 25. If 100. ml of carbon disulfide (density 1.26 g/ml) is burned completely, how many liters of SO 2 and of CO 2 are formed? CS 2 (l) 3O 2 (g) CO 2 (g) 2SO 2 (g) Holt Chemistry 5 Stoichiometry
TEACHER RESOURCE PAGE Answer Key Concept Review: Calculating Quantities in Reactions 1. mole 2. balance 3. relative 4. coefficients 5. molar mass 6. liquids 7. density 8. Avogadro s number 9. c 10. b 11. b 12. c 13. c 14. 1.00 g Ca 3 (PO 4 ) 2 1 mol Ca 3 (PO 4 ) 2 /310.18 g Ca 3 (PO 4 ) 2 2 mol P/1 mol Ca 3 (PO 4 ) 2 30.97 g P/1 mol P 0.200 g P 15. 18 g Al 1 mol Al/26.98 g Al 2 mol AlCl 3 /2 mol Al 133.33 g AlCl 3 /1 mol AlCl 3 89 g AlCl 3 16. 1150 g C 6 H 12 O 6 1 mol C 6 H 12 O 6 /180.18 g C 6 H 12 O 6 2 mol C 2 H 5 OH/1 mol C 6 H 12 O 6 46.08 g C 2 H 5 OH/1 mol C 2 H 5 OH 588 g C 2 H 5 OH 17. 25.5 g Mg 1 mol Mg/24.30 g Mg 1 mol O 2 /2 mol Mg 0.525 mol O 2 18. 1.0 mol C 5 H 11 OH 10 mol CO 2 /2 mol C 5 H 11 OH 44.01 g CO 2 /1 mol CO 2 220 g CO 2 19. 500.0 g CCl 3 NO 2 1 mol CCl 3 NO 2 /164.37 g CCl 3 NO 2 1 mol CH 3 NO 2 /1 mol CCl 3 NO 2 3.042 mol CH 3 NO 2 20. 122 g KClO 3 1 mol KClO 3 /122.55 g KClO 3 32.00 g O 2 /1 mol O 2 3 mol O 2 /2 mol KClO 3 1 L O 2 /1.33 g O 2 35.9 L O 2 21. 3.4 L O 2 1.33 g O 2 /1 L O 2 1 mol O 2 /32.00 g O 2 2 mol KCl/3 mol O 2 74.55 g KCl/1 mol KCl 7.0 g KCl 22. 910 g Ca 3 P 2 1 mol Ca 3 P 2 /182.18 g Ca 3 P 2 2 mol PH 3 /1 mol Ca 3 P 2 33.99 g PH 3 /1 mol PH 3 1 L PH 3 /1.517 g PH 3 220 L PH 3 23. 93 g P 1 mol P/30.97 g P 5 mol O 2 /4 mol P 32.00 g O 2 /1 mol O 2 100. g air/23 g O 2 520 g air 24. 5.00 metric tons coke 85.5% C/100.0% coke 1.00 10 6 g/1 metric ton 44.01 g CO 2 /1 mol CO 2 1 mol C/12.01 g C 1 mol CO 2 /1 mol C 1 metric ton/1.00 10 6 g 15.7 metric tons CO 2 25. 100 ml CS 2 1.26 g CS 2 /1 ml CS 2 1 mol CS 2 /76.15 g CS 2 2 mol SO 2 /1 mol CS 2 22.4 L SO 2 /1 mol SO 2 74.1 L SO 2 74.01 L SO 2 1 mol CO 2 /2 mol SO 2 37.1 L CO 2 Concept Review: Limiting Reactants and Percentage Yield 1. excess 2. limiting, product 3. limiting 4. stoichiometric 5. limiting 6. excess 7. percentage 8. actual; theoretical 9. actual 10. actual 11. 3.00 g Mg (1 mol Mg/24.30 g Mg) 0.123 mol Mg 2.20 g O 2 (1 mol O 2 /32.00 g O 2 ) 0.688 mol O 2 0.0688 mol O 2 (2 mol Mg/1 mol O 2 ) 0.138 mol Mg needed. Mg is limiting. 0.123 mol Mg (2 mol MgO/2 mol Mg) (40.30 g MgO/1 mol MgO) 4.96 g MgO Holt Chemistry 86 Stoichiometry