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Hunter College, CUNY CHEM CHEM 121.LB Virtual Lab Day 11: Le Chtelier's Principle https://www.youtube.com/watch?

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Question Virtual Lab Day 11: Le Châtelier's Principle https://www.youtube.com/watch?v=T97YyD72smk Assignment Part 1 Write both of the chemical equations from the two videos, putting heat as a reactant or product in each case, and then very briefly explain how Le Châtelier's principle can be used to explain the results. Part 2 Some of our labs and some of the reactions in lecture have dealt with Le Châtelier's principle. So, use Le Châtelier's principle to explain the follow. Lab Day 4: Distillation You have an impure sample of hexane you want to purify by distillation. It is in the distillation apparatus, and an equilibrium exists between the liquid and the hexane vapor above the liquid. You start heating it up, so what happen to the equilibrium and why. (Hint, is going from a liquid to a gas exothermic or endothermic?) Lab Day 7: Functional Group Characterization In our regular lab in the laboratory, esters are made by a Fischer esterification. If you doing this reaction with equal molar amounts of the carboxylic acid and alcohol, you get an equilibrium that isn't very good for our purposes. So what happens to that equilibrium when extra alcohol is added? Lab Day 8: Extractions Consider a separatory funnel that contains water, ether, and some phenol, which has some solubility in both solvents. You shake it up to create a equilibrium concentration of the phenol in the two solvents. Without removing anything, you double the amount of water in the separatory funnel. How does the equilibrium behave when you remix the two phases? Lab Day 9: Chromatography Imagine a situation where you have silica gel (the type used for chromatography) in a test tube with a solvent mixture and a little food coloring. (You can pick your favorite color.) You shake the test tube to establish an equilibrium, so part of your food coloring is still dissolved, and part is bound to the surface of the silica gel. You disturb that equilibrium by putting twice as much solvent into the test tube and reshaking. What happens to the equilibrium? From Lecture You have cyclohexene, water, cyclohexanol, and a little sulfuric acid catalyst in a test tube at 60 o C and everything is at equilibrium. Indicate what happens to that equilibrium and why with the following changes. (Note that adding water to an alkene is exothermic) 1) You heat it up to 80 o C. 2) You cool it down to 40 o C. 3) You remove some of the water. 4) You add a little more water. Use your answers to explain how to most successfully make cyclohexanol from cyclohexene, and how to most successfully make cyclohexene from cyclohexanol. NB. Hunter College Lab manual is uploaded on coursehero if you want a better view of what to do.

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