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Can you refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium? In this investigation, you will observe the changes that result when you add more of, or take away some of, one of the components of the equilibrium and determine if there are trends in the behavior of equilibrium systems. Equilibrium Lab—Text VersionIntroductionIn this experiment, you will investigate how increasing or decreasing the concentration of one component of an equilibrium system affects the position of equilibrium.You will observe color changes that indicate how concentrations change. You will also examine graphs that depict those changes in concentration as the system adjusts to the stress and reaches a new equilibrium position. You will investigate an equilibrium system between two cobalt complex ions. Co(H2O)62+ + 4Cl– ⇌ CoCl42– + 6H2O.In aqueous solution, Co(H2O)62+ is pink, CoCl42– is blue, and Cl– and H2O are colorless. The distinctive colors of the two cobalt (II) species in solution provide a visual comparison of concentrations. This allows you to observe how the concentrations of the two cobalt complex ions compare within the system. Observations Select each control test tube to compare the concentrations of reactants and products. Text that appears when test tube A is selected: When there is significantly more Co(H2O)62+ than CoCl42– in the test tube, the solution is pink, as in control test tube A. Text that appears when test tube B is selected: When the amounts of Co(H2O)62+ and CoCl42– are approximately equal in the test tube, the solution is purple, as in control test tube B.Text that appears when test tube C is selected: When there is significantly more CoCl42– than Co(H2O)62+ in the test tube, the solution is blue, as in in control test tube C. These test tubes each contain the same solution, at an equilibrium position with approximately equal concentrations of Co(H2O)62+ and CoCl42–. With each addition, you will be either increasing the amount of one species within the equilibrium or decreasing the amount (due to a secondary reaction). Each stress may cause a change in the rate of the forward or reverse reaction until a new equilibrium is reached. Record your observations carefully. Observations Procedure Trial One: Adding HCl to solution with approximately equal concentrations of CoCl42– and Co(H2O)62+Add a solution of HCl to test tube 1 and stir with a clean, dry stirring rod. This increases the amount of Cl– in the test tube. Record your observations of the stress, color change, and graph. Observations Trial Two: Adding AgNO3 to solution with higher concentration of CoCl42– than Co(H2O)62+Take test tube 1 again, and add a solution of AgNO3. Stir with a clean, dry stirring rod. The added Ag+ ions react with Cl– to form the insoluble precipitate AgCl. Record your observations of the stress, color change, and graph. Observations Trial Three: Adding H2O to solution with approximately equal concentrations of CoCl42– and Co(H2O)62+Add liquid H2O to test tube 2 and stir with a clean, dry stirring rod. Record your observations of the stress, color change, and graph. Observations Trial Four: Adding NaCl to solution with approximately equal concentrations of CoCl42– and Co(H2O)62+Add NaCl salt to test tube 3 and stir with a clean, dry stirring rod. Stirring will cause the NaCl to dissolve and dissociate in the solution.Record your observations of the stress, color change, and graph.Observations Trial Five: Adding H2O to solution with higher concentration of CoCl42– than Co(H2O)62+Now that all the NaCl has dissolved in test tube 3, add liquid H2O. Then stir with a clean, dry stirring rod. Record your observations of the stress, color change, and graph.Observations Trial Six: Adding CaCl2 to solution with higher concentration of Co(H2O)62+ than CoCl42–Now, take the solution in test tube 2 and add solid CaCl2 salt. Record your observations of the stress and color change. There is no graph for this trial. Observations You’ve completed this lab investigation. Be sure you have all the observations recorded.FILL OUT LAB REPORT. _06_lab_report.doc Unformatted Attachment Preview Equilibrium Lab Report Instructions: For this investigative phenomenon, you will observe the changes that result when you add more of, or take away some of, one of the components of the equilibrium (known as a stress) and determine if there are trends in the behavior of equilibrium systems. Record your observation in the lab report below. You will submit your completed report. Title: Objective(s): Hypothesis: Explain the relationship between forward and reverse reactions at equilibrium and predict how changing the amount of a reactant or product (creating a stress) will affect that relationship. For example (select one from each underlined section) If the amount of (reactant or product) increases, the rate of the (forward or reverse) reaction will (increase or decrease) to reach a new equilibrium. If the amount of (reactant or product) decreases, the rate of the (forward or reverse) reaction will (increase or decrease) to reach a new equilibrium. Procedure: Access the virtual lab and complete the inquiry experiment. List your controlled variables, independent variable, and dependent variable. Explain why these are the variables. Summarize the steps of the experimental procedure. Materials: Equilibrium Virtual Lab Variables: Remember, controlled variables are factors that remain the same throughout the experiment. An independent (test) variable changes so that the experimenter can see the effect on other variables. The dependent (outcome) variable will change in response to the test variable. Controlled variables: Independent variable: Dependent variable: Summary of Steps: Include a summary of steps here. We have included the first two important steps to get you started. You can summarize the rest from the virtual lab. 1. Write down the equilibrium equation you are investigating using the information provided by the introduction within the virtual lab activity Equilibrium reaction: 2. Select each control test tube to compare the concentrations of reactants and products. Write down what each indicator color means about the concentrations of reactants and products in solution. Pink means: Blue means: Purple means: Data: For each trial, make sure you record the initial color of the solution, what is added to the test tube (a description of the stress), and what happened after the substance was added. Also include a screen shot, sketch, or description of each graph of each trial. Initial Color Trial One: Tube 1 Adding HCL Trial Two: Tube 1 Adding AgNO3 Trial Three: Tube 2 Adding H2O Trial Four: Tube 3 Adding NaCl End Color Screenshot, sketch, or description Trial Five: Tube 3 Adding H2O Trial Six: Tube 2 Adding CaCl2 Calculations and Analysis: 1. Looking at the graphs provided in the experiment, describe what is happening at the point where all lines are horizontal: • in terms of reaction rate • in terms of concentration • in terms of reaction completion 2. Create a general graph representing concentration vs. time for trial 6. • Remember, this is a qualitative graph showing a general comparison of concentrations observed in the reaction. There are no data values to be plotted on the graph. • Be sure to label each axis and line on the graph. Conclusion: Write a conclusion statement that addresses the following questions: • • • Explain what the color change indicated about the changes in the concentrations of Co(H2O)62+ and CoCl42– in each trial. Do your data support or fail to support your hypothesis (include examples)? How do you think the investigation can be explored further? Post-Lab Reflection Questions Answer the reflection questions using what you have learned from the lesson and your experimental data. It will be helpful to refer to your chemistry journal notes. Answer questions in complete sentences. 1. How did the change of stress (adding or removing reactants or products) cause a shift in the equilibrium system of your solutions? Use data to support your answer. Make sure you discuss all four stress changes: a. Adding a reactant b. Adding a product c. Removing a reactant d. Removing a product 2. Concentration is just one stress that can affect the equilibrium position. Another is temperature. Describe how you would design this experiment to test for the effects of temperature on equilibrium position. Include a description of the experiment and describe what you would look for to see changes in the equilibrium position. 3. The equilibrium system Co(H2O)62+ + 4Cl– ⇌ CoCl42– + 6H2O is endothermic as written, meaning heat is a reactant for the forward reaction and a product for the reverse reaction. Based on that information and your findings from this experiment, predict what you would expect to observe in the experiment you described above when you tested the effects of temperature on an equilibrium position. ... Purchase answer to see full attachment