Answered: 2. a. Which cobalt complex was favored…

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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LE CHATELIER'S PRINCIPLE Problem: How do systems at equilibrium respond to changing conditions? Introduction: Le Chatelier's Principle describes the effect that applying various types of stress has on the position of a system at equilibrium that is, whether it will shift to increase or decrease the concentration(s) of products in the equilibrium system. The principle tells us that when a system at equilibrium is subjected to stress, it will shift in such a way as to relieve the effects of that stress. Stresses include variations in the concentrations of reactants or products, the temperature of the system, and (for reactions involving gases) the pressure. Of these, only temperature changes the equilibrium constant's value. Most of our investigations occur in open systems, usually in water solutions. Unless gases are involved in the reaction, the volume of the system is just the volume of the solution, and pressure is of little or no consequence. This permits us to simplify Le Chatelier's Principle to read: For any reaction system at equilibrium in solution: If you add a reactant or a product to the system, it will try to consume what was added; if you remove a reactant or a product from the system, it will try to replace what was removed. In this experiment, you will observe what Le Chatelier's Principle means. Your investigation will deal with two complex ions, both containing cobalt (II); they are Co(H₂O) and CoCl. The procedure is short and should not require more than 15 minutes to complete. When you have finished and cleaned your work area, return to your desk for the post-lab discussion, during which we will talk about what you saw and what it signifies in terms of the reaction system being investigated. You will need to take good notes during both the experiment and the post-lab session since those notes will help you answer the questions pertaining to the experiment. Materials: Apparatus 50-mL beaker 10-mL test tube (5) . Hot plate loe bath (ice o/o student) Reagents: Cobalt chloride hexahydrate (CoCl26H₂O) Ethanol (or methanol) 12 M Hydrochlorio acid, HCl(aq) Calcium chloride pellets, CaCl₂ (5) Acetone Silver nitrate solution. AgNO₂ (aq), 0.10 M Distilled water (c/o student) Safety: 1. Safety goggles and a laboratory gown must be always worn in the laboratory. 2 Cobalt and silver solutions are mildly toxic, so you must wash your hands thoroughly before leaving the laboratory 3. Silver nitrate will stain skin and clothing. Wipe up all spills with large amounts of water. 4. Concentrated hydrochloric acid will attack skin and clothing. Neutralize acid spills on laboratory surfaces before wiping them up. 5. Be careful using the hot plate. Remember that hot surfaces look the same as cool ones. Use a hot pad to transfer hot containers from the hot plate. Procedure: An asterisk (*) indicates that written observations are called for in that step. 1. Thoroughly dry your 50-mL beaker with a paper towel, then use the markings on the side to measure about 25-30 mL of ethanol into the beaker. 2. Examine the solid cobalt (II) ohloride, noting both its color and the formula for the compound, as shown on the label of the stock bottle. 3. Place a small sample of the 2 g of solid in the beaker of ethanol 4. Divide most of the solution among 5 test tubes, leaving about 1/4 of the solution in the beaker. The actual volume is important, but they should all have approximately equal volumes of solution. 5. To one of the test tubes, add 5 drops of distilled water, one drop at a time, recording observations after each drop. Duplicate the process with each of the three other test tubes, so that all four are the same color. Use four of the five for step 6, retaining one as a control, for comparison purposes." 6. a. Take one of the test tubes from step 5 to the fume hood. Use the dropper provided with the acid to CAREFULLY add 5 drops of concentrated hydrochloric acid, one drop at a time, to the solution in the test tube. b. To a second test tube from step 5, add 2 small pellets of solid calcium chloride o. To the third test tube, add 3-4 drops of acetone." d. To your fourth test tube, add 10 drops of 0.1 M silver nitrate, AgNO,, one drop at a time." 7. To the solution remaining in the beaker, do not add water, Place the beaker on a hot plate and warm it until a color change occurs. 8. Finally, chill the beaker in an ice bath, to see whether the color change in step 8 is reversible. Cleaning Up: 1. All solutions contain cobalt and should be transferred to the assigned waste container. The teacher will neutralize the acid (from step 6b) and then dispose of the combined waste in an approved, safe manner. 2. Make certain that all glassware is clean, bottle caps are back in place, and that all is left as you found it. 3. Wash your hands with soap and water before leaving the laboratory 3. Acetone absorbs water. Use this fact and Le Chatelier's Principle to explain the color change that you saw when you added acetone to the third test tube in step 6. 4. Silver chloride, AgCl, is a white solid. The equilibrium constant is K = 6x10° for: Ag+(aq) + Cl-(aq) = AgCl(s) a. At equilibrium, would you expect to have mostly silver and chloride ions in solution, or mostly solid silver chloride? Explain. b. What color was the solid you formed in step 6d? What must it have been? c. What color did the liquid in the test tube turn? Which complex of cobalt was favored? Explain. d. Use Le Chatelier's Principle to explain why the liquid in the test tube underwent the color change. Above all information see. now solve only below images questions Qno2. A b and c Full accurate okk Solve self idont have reaction etc

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4. Experiment 4 Le Chateliers Principle.pdf
2. a. Which cobalt complex was favored in both 6a and 6b?
027%
b. What ion is common to both of the reagents you used to bring about the color changes in
these two steps?
c. Use Le Chatelier's Principle to explain why the color changes occurred in each case.
...

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2. a. Which cobalt complex was favored in both 6a and 6b? b. What ion is common to both of the reagents you used to bring about the color changes in these two steps? c. Use Le Chatelier's Principle to explain why the color changes occurred in each case.