Preview of “Lab 8 InLab - Eq. and LeChatelier's Principle”

Preview of “Lab 8 InLab - Eq. and LeChatelier's Principle”

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Unformatted text preview: 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle Steve Yarush CH102, section 021, Fall 2012 Instructor: Brandon Zoellner WebAssign Lab 8 InLab -­ Eq. and LeChatelier's Principle (In-­Lab) Current Score : 46.52 / 50 Due : Tuesday, October 23 2012 05:25 PM EDT The due date for this assignment is past. Your work can be viewed below, but no changes can be made. Important! Before you view the answer key, decide whether or not you plan to request an extension. Your Instructor may not grant you an extension if you have viewed the answer key. Automatic extensions are not granted if you have viewed the answer key. Request Extension 1. 10.52/14 points | Previous Answers NCSUGenChem102LabV1 8.IL.01. Green checks and red X's are not displayed for this question. Complete the following table. (Select all that apply.) Data Table A: Observations and Conclusions for Fe3+ + SCN – Well # 1 Stress Applied None: Control for Comparison FeSCN2+ Observations Upon Applying Stress (deep) red solution solution becomes darker red solution becomes lighter red solution decolorizes solution turns blue 2 Add 0.10 M Fe(NO3)3 solution turns pink solution turns purple a solid/precipitate forms no significant change occurs -‐‑Responses/last?dep=4449740 1/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle solution becomes darker red solution becomes lighter red solution decolorizes 3 Add 0.05 M NaSCN solution turns blue solution turns pink solution turns purple a solid/precipitate forms no significant change occurs solution becomes darker red solution becomes lighter red solution decolorizes solution turns blue solution turns pink 4 Add 1.0 M AgNO3 solution turns purple a solid/precipitate forms no significant change occurs -‐‑Responses/last?dep=4449740 2/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle Add 1.0 M NaNO3 5 solution becomes darker red solution becomes lighter red solution decolorizes solution turns blue solution turns pink solution turns purple a solid/precipitate forms no significant change occurs In-­Lab Question 1. When Fe(NO3)3 was added to the system, (a) Which ion in the equilibrium system caused the '"stress"? Fe3+ SCN – FeSCN2+ none (b) Which way did the equilibrium shift? right left none (c) What happened to the concentration of SCN –? -‐‑Responses/last?dep=4449740 3/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle increase decrease no change (d) What happened to the concentration of FeSCN2+? increase decrease no change In-­Lab Question 2. When NaSCN was added to the system, (a) Which ion in the equilibrium system caused the '"stress"? Fe3+ SCN – FeSCN2+ none (b) Which way did the equilibrium shift? right left none (c) What happened to the concentration of Fe3+? -‐‑Responses/last?dep=4449740 4/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle increase decrease no change (d) What happened to the concentration of FeSCN2+? increase decrease no change In-­Lab Question 3. When AgNO3 was added to the system, it caused the precipitation of solid AgSCN. (a) Which ion in the equilibrium had its concentration changed by addition of AgNO3? Fe3+ SCN – FeSCN2+ none (b) Did the concentration of that ion increase or decrease? increase decrease no change (c) When AgNO3 was added, which way did the equilibrium shift? -‐‑Responses/last?dep=4449740 5/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle right left none In-­Lab Question 4. Choose the best explanation for the result you observed when NaNO3 was added. Addition of NO3– forms a chemiluminescent compound, FeSCN(NO3)2, that absorbs any color changes. Na+ and NO3– cause equal amounts of NaSCN and FeSCN(NO3)2 to form. Thus no color change occurs. Addition of colorless Na+ and NO3– suppresses any color change due to dilution. Na+ and NO3– are not present in the equilibrium equation, and do not affect the concentration of FeSCN2+ which is responsible for the coloration. Equilibrium and Le Chatelier's Principle 2. 12/12 points | Previous Answers NCSUGenChem102LabV1 8.IL.02. Green checks and red X's are not displayed for this question. Complete the following table. (Select all that apply.) Data Table B: Observations for the Equilibrium: CoCl 42– + 6 H2O Experiment Stress Applied -‐‑Responses/last?dep=4449740 Co(H2O)62+ + 4 Cl – Observations Upon Applying Stress 6/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle solution becomes darker red solution becomes lighter red Well 1A Add 12 M HCl solution decolorizes solution turns blue solution turns pink solution turns purple a solid/precipitate forms no significant change occurs solution becomes darker red solution becomes lighter red solution decolorizes solution turns blue Well 1B Add water solution turns pink solution turns purple a solid/precipitate forms no significant change occurs Well 2A Add 12 M HCl -‐‑Responses/last?dep=4449740 7/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle solution becomes darker red solution becomes lighter red solution decolorizes solution turns blue solution turns pink solution turns purple a solid/precipitate forms no significant change occurs solution becomes darker red solution becomes lighter red solution decolorizes solution turns blue Well 2B Add 0.1 M AgNO3 solution turns pink solution turns purple a solid/precipitate forms no significant change occurs Beaker 1 Heat Solution -‐‑Responses/last?dep=4449740 8/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle solution becomes darker red solution becomes lighter red solution decolorizes solution turns blue solution turns pink solution turns purple a solid/precipitate forms no significant change occurs solution becomes darker red solution becomes lighter red solution decolorizes solution turns blue Beaker 2 solution turns pink Cool Solution solution turns purple a solid/precipitate forms no significant change occurs In-­Lab Question 5. Adding HCl has the effect of adding Cl – ions to the system. When Cl – was added to the system, (a) Which way did the equilibrium shift? right left none -‐‑Responses/last?dep=4449740 9/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle (b) What happened to the concentration of CoCl 42–? increase decrease no change (c) What happened to the concentration of Co(H2O)62+? increase decrease no change In-­Lab Question 6. When water was added to the system, (a) Which way did the equilibrium shift? right left none (b) What happened to the concentration of CoCl 42–? increase decrease no change (c) What happened to the concentration of Co(H2O)62+? -‐‑Responses/last?dep=4449740 10/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle increase decrease no change Equilibrium and Le Chatelier's Principle 3. 5/5 points | Previous Answers NCSUGenChem102LabV1 8.IL.03. Green checks and red X's are not displayed for this question. Use the data you recorded in Data Table B, to answer the following questions. In-­Lab Question 7a. Which ion in the equilibrium had its concentration changed by the addition of AgNO3? Cl – Co2+ H 2O CoCl 42– In-­Lab Question 7b. Did the concentration of that ion increase or decrease? increase decrease no change In-­Lab Question 7c. When AgNO3 was added, which way did the equilibrium shift? -‐‑Responses/last?dep=4449740 11/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle right left none In-­Lab Question 8. State a general rule concerning a system at equilibrium when more of one of the components is added. If a component of the equilibrium reaction is added, the equilibrium will shift toward the same side of the reaction to return to the lowest free energy. If a component of the equilibrium reaction is added, the equilibrium will shift toward the same side of the reaction to keep the value of K constant. If a component of the equilibrium reaction is added, the equilibrium will shift toward the opposite side of the reaction to consume the added material. If a component of the equilibrium reaction is added, the equilibrium will shift toward the opposite side of the reaction to keep the rate of the forward reaction greater than the rate of the reverse reaction. In-­Lab Question 9. State a general rule concerning a system at equilibrium when one of the components is removed. If a component of the equilibrium reaction is removed, the equilibrium will shift toward the opposite side of the reaction to keep the value of K constant. If a component of the equilibrium reaction is removed, the equilibrium will shift toward the opposite side of the reaction to return to the lowest free energy. If a component of the equilibrium reaction is removed, the equilibrium will shift toward the same side of the reaction to replace the removed material. If a component of the equilibrium reaction is removed, the equilibrium will shift toward the same side of the reaction to keep the rate of the reverse reaction greater than the rate of the forward reaction. Equilibrium and Le Chatelier's Principle -‐‑Responses/last?dep=4449740 12/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle 4. 4/4 points | Previous Answers NCSUGenChem102LabV1 8.IL.04. Green checks and red X's are not displayed for this question. Use the data you recorded in Data Table B, to answer the following questions. In-­Lab Question 10a. Which way did the equilibrium shift upon heating? right left none In-­Lab Question 10b. Which way did the equilibrium shift upon cooling? right left none In-­Lab Question 10c. A general rule concerning temperature changes to equilibrium systems is that the input of energy (raising the temperature) shifts the equilibrium to the higher energy side of the equilibrium. Based on your observations, which side of the equilibrium is the higher energy side? the product side the reactant side In-­Lab Question 10d. Is the reaction CoCl 42– + 6 H2O Co(H2O)62+ + 4 Cl – endothermic or exothermic? exothermic endothermic Equilibrium and Le Chatelier's Principle -‐‑Responses/last?dep=4449740 13/14 11/6/12 Lab 8 InLab -‐‑ Eq. and LeChatelier's Principle 5. 15/15 points | Previous Answers NCSUGenChem102LabV1 1.IL.04. Type your name into the answer box. This space will be used by your instructor to record your points for class participation in the lab using the User Participation Rubric. Steve Yarush Key: space for TA comments Score: 15 out of 15 Comment: -‐‑Responses/last?dep=4449740 14/14 ...
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