Limiting Reactants and Percent Yield

AP Chemistry Limiting Reactants and Percent Yield 1. Aluminum metal reacts with chlorine gas in a synthesis reaction. a. Write the balanced equation for this reaction. b. If 15.2 g of aluminum reacts with 39.1g of chlorine, identify the limiting reactant. c. Determine the mass in grams of the product formed. d. Determine the mass in grams of excess reactant remaining when the reaction is complete. e. If you made 50.0g of AlCl3 in the lab, what is your percent yield? f. If the percent yield were 83.65%, how much could be expected to be made in the experiment? 2. Fe(s) + O2(g)  Fe3O4(s) a. When 13.54 g of O2 is mixed with 12.21 g of Fe, which is the limiting reactant? b. What mass in grams of iron oxide is produced? c. What mass in grams of excess reactant remains when the reaction is complete? d. Kelly performed completed this reaction in a lab and made15.88 g of Fe3O4, what was her percent yield? 3. Diiodine pentoxide is useful in devices such as respirators because it reacts with the dangerous gas carbon monoxide, CO, to produce relatively harmless CO2 according to the following equation: AP Chemistry a. I2O5 + CO  I2 + CO2 In testing a respirator, 2.00g of carbon monoxide gas is passed through diiodine pentoxide. Upon analyzing the results, it is found that 3.17g of I2 was produced. Calculate the percent yield of the reaction. b. Assuming that the yield in part a resulted because some of the CO did not react, calculate the mass of CO that passed through. 4. Cu(s) + Cl2(g)  CuCl2(s) a. If 12.5 g Cu reacts with excess chlorine, calculate the theoretical yield of CuCl 2. b. If ony 25.4g of CuCl2 was produced, what is the percent yield? 5. Sodium hyperchlorite, NaClO, the main ingredient in household bleach, is produced by bubbling chlorine gas through a strong lye(sodium hydroxide, NaOH) solution. The following equation shows the reaction that occurs. NaOH + Cl2  NaCl + NaClO + H2O a. What is the percent yield of the reaction if 1.2kg of Cl 2 reacts to form .90kg of NaClO? 6. The percent yield for the reaction PCl3 + Cl2  PCl5 the reaction of 73.7 g of PCl3 with excess chlorine? is 83.2%. What mass of PCl5 is expected from AP Chemistry Conservation of Mass Worksheet Example: A compound containing carbon and hydrogen is analyzed. When a 1.2543 gram sample is burned completely in excess oxygen, 3.671 grams of CO2(g) is formed. What is the empirical formula of this compound? a) Write a skeleton equation for this reaction. If you do not know the formula for every compound, put information about what you do know in parenthesis. b) How many grams of carbon are in 3.671 g of CO2? Where did all of this carbon come from? How much carbon was in the original sample of the unknown compound? c) What is the percent composition of carbon and hydrogen in the unknown compound? d) Determine the empirical formula of this compound, now that you know the percent composition. e) The molar mass of this compound is determined to be 30.08 g/mol. What is the correct molecular formula of the unknown compound? ONE A compound containing carbon and hydrogen is analyzed. Combustion of a 16.81 g sample of this compound produces 38.91 g of CO2(g). What is the empirical formula of this compound? What is the molecular formula if the molar mass of the compound is determined to be 38.03 g/mol? TWO A compound containing carbon and hydrogen is analyzed. Combustion of a 0.213 g sample of this compound yields 0.2132 g of water. What is the empirical formula of this compound? What is the molecular formula if the molar mass of the compound is 81.15 g/mol? THREE A compound containing carbon, hydrogen, and oxygen is analyzed. Combustion of a 3.4 g sample of this compound produces 6.79 g of CO2(g) and 2.7843 g of water vapor. What is the empirical formula of this compound? What is the molecular formula if the molar mass of the compound is 44.06 g/mol? AP Chemistry Percent Composition and Molecular Formula Worksheet 1) What’s the empirical formula of a molecule containing 65.5% carbon, 5.5% hydrogen, and 29.0% oxygen? 2) If the molar mass of the compound in problem 1 is 110 grams/mole, what’s the molecular formula? ________________________________________________________________ 3) What’s the empirical formula of a molecule containing 18.7% lithium, 16.3% carbon, and 65.0% oxygen? 4) If the molar mass of the compound in problem 3 is 73.8 grams/mole, what’s the molecular formula?