Chem 233 Final Exam Questions With Complete Solutions

In the experiment, you added water to the reaction vessel after the reaction was complete, but we did not discuss why. Based on what happened after adding the water, which of the following is the reason for the addition of water? a) lower the solubility of the product in solution so it precipitated out b) increase the solubility of the product in solution so it precipitated out c) lower the solubility of the product in solution so it stayed in solution d) increase the solubility of the product in solution so it stayed in solution correct answer: a) lower the solubility of the product in solution so it precipitated out You recrystallize the product of a bromination reaction by dissolving the entire product in hot solvent, cooling to room temperature, and then collecting the solid that crystallized. However, you are disappointed with your yield. Select all of the following actions that would increase the amount of solid recovered from the recrystallization. a) performing a hot filtration b) cool the recrystallization solution in an ice bath before collecting the crystals c) lower the amount of solvent used in the recrystallization while keeping all impurities dissolved e) increase the amount of solvent used in the recrystallization while keeping all impurities dissolved correct answer: b) cool the recrystallization solution in an ice bath before collecting the crystals c) lower the amount of solvent used in the recrystallization while keeping all impurities dissolved Calculate the percent recovery of a recrystallization of a 1.3 g sample of solid to the tenths place if you recover 0.88 g after the recrystallization. Round to the nearest tenths. correct answer: 67.7 g. After performing a recrystallization, you calculate a percent recovery of 110%. Select all possible reasons for this result. a) The crystals were not dried properly after the recrystallization b) The recrystallized solid became more dense, increasing its mass c) Impurities were added to the solid during the recrystallization process d) Some of the solid melting during the weighing process, increasing its mass correct answer: a) The crystals were not dried properly after the recrystallization c) Impurities were added to the solid during the recrystallization process After brominating an alkene, you isolate a solid that is ora