Chemistry I Chapter 9 Stoichiometry Objective Sheet Equation 1 2 C 2 H 2 (g) + 5 O 2 (g) 4 CO 2 (g) + 2 H 2 O (g), at STP C 2 H 2 (acetylene) 26 g/mol O 2 32 g/mol CO 2 44 g/mol H 2 O 18 g/mol Objectives: 1. Define stoichiometry 2. Solve the following types of reaction stoichiometry problems: mol-mol (moles to moles) mole-mass or mass-mole mole-volume or volume-mole mass-mass volume-volume mass-volume or volume-mass 3. Give the mole ratio for any two substances in a chemical equation. Give the mole ratios for all species in Equation 1. 4. Calculate the amount in moles of a reactant or product given the amount in moles of a different reactant or product. Use Equation 1 to calculate the amount of moles of water that can be produced from 4 moles of C 2 H 2 5. Calculate the mass of a reactant or product given the amount in moles of a different reactant or product. Use Equation 1 to calculate the mass of carbon dioxide that could be produced from burning 2.5 mol C 2 H 2 in unlimited oxygen. 6. Calculate the amount in moles of a reactant or product given the mass of a different reactant or product. Using Equation 1, calculate the number of moles of oxygen needed to produce 1000. grams of carbon dioxide. 7. Calculate the mass of a reactant or product, given the mass of a different reactant or product. Given equation 1, calculate the mass of C 2 H 2 needed to react with 25 grams of oxygen. 8. Calculate the volume of a reactant or product, given the moles of a different reactant or product. Given equation 1, calculate the volume of carbon dioxide which would be produced by burning 60. moles of C 2 H 2 in unlimited oxygen. 1
Chemistry I Chapter 9 Stoichiometry Objective Sheet Equation 1 2 C 2 H 2 (g) + 5 O 2 (g) 4 CO 2 (g) + 2 H 2 O (g), at STP C 2 H 2 (acetylene) 26 g/mol O 2 32 g/mol CO 2 44 g/mol H 2 O 18 g/mol 9. Calculate the mass of one reactant or product when given a volume at STP of another reactant or product. Given Equation 1, calculate the mass of C 2 H 2 needed to produce 100 liters of water vapor at STP. 10. Calculate the volume of one reactant or product from the volume of another, assuming they are gases at STP. Using equation 1, how many liters of water can be produced from 46 liters of C 2 H 2 in unlimited oxygen? 11. Define limiting reactant. Tell how you know when you have a limiting reactant problem. 12. Solve limiting reactant problems. Using Equation 1, if 100 g of C 2 H 2 react with 100 g of oxygen, calculate the number of moles of carbon dioxide generated. Then calculate the mass of carbon dioxide generated. Then calculate the volume at STP of carbon dioxide generated. What is the limiting reactant? What is the reactant in excess? How much of the reactant in excess will be left over? 13. Calculate the theoretical yield, the actual yield, and the percent yield. In equation 1, if 1 mole of C 2 H 2 burned in unlimited oxygen, what is the theoretical yield of carbon dioxide in liters at STP? If 28.5 liters of carbon dioxide is produced, what is the percent yield? What is the actual yield? 2
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3 Cu (s) + 8 HNO 3 (aq) 3 Cu(NO 3 ) 2 (aq) + 2 NO (g) + 4 H 2 O (l) Assume this reaction occurs at STP. Cu--63.5 g/mol; HNO 3 --63.0 g/mol; Cu(NO 3 ) 2 --187.5 g/mol; NO--30.0 g/mol; H 2 O--18.0 g/mol Calculate when given the above information, 1. The number of moles of Cu(NO 3 ) 2 from 5.00 moles of HNO 3 with excess copper (Cu). 2. The moles of water from 7.00 moles of copper with excess HNO 3. 3. The number of moles of Cu needed to react with 10. grams of HNO 3 4. The moles of NO gas that will be formed if 40.0 grams of Cu(NO 3 ) 2 are formed 5. The grams of Cu(NO 3 ) 2 that would be formed if 36.1 grams of water were formed. 5
3 Cu (s) + 8 HNO 3 (aq) 3 Cu(NO 3 ) 2 (aq) + 2 NO (g) + 4 H 2 O (l) Assume this reaction occurs at STP. Cu--63.5 g/mol; HNO 3 --63.0 g/mol; Cu(NO 3 ) 2 --187.5 g/mol; NO--30.0 g/mol; H 2 O--18.0 g/mol 6. The moles of Cu needed to generate 44.8 liters of NO gas. 7. The grams of HNO 3 needed to make 100 grams of Cu(NO 3 ) 2. 8. The volume of NO gas at STP generated from 12.0 g of copper. 9. The volume of gas generated using 3.0 g copper. 11. The mass of copper (II) nitrate produced if 10. g of copper reacted with 10. g of HNO 3. This is a limiting reactant problem. Wait until you learn how to do this type of problem. 6
3 Cu (s) + 8 HNO 3 (aq) 3 Cu(NO 3 ) 2 (aq) + 2 NO (g) + 4 H 2 O (l) Assume this reaction occurs at STP. Cu--63.5 g/mol; HNO 3 --63.0 g/mol; Cu(NO 3 ) 2 --187.5 g/mol; NO--30.0 g/mol; H 2 O--18.0 g/mol 11. The mass of water produced if 25 grams of copper reacted with 100 grams of HNO 3. What is the limiting reactant? What is the reactant in excess? What percent yield would the experiment have if 8.6 grams of water were produced? What percent error would this experiment have? 7