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.
Write down the equilibrium equation you are investigating using the information provided by the introduction within the virtual lab activity
Equilibrium reaction:
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
End Color
Screenshot, sketch, or description
Trial One:
Tube 1
Adding HCL

Trial Two:
Tube 1
Adding AgNO3

Trial Three:
Tube 2
Adding H2O

Trial Four:
Tube 3
Adding NaCl

Trial Five:
Tube 3
Adding H2O

Trial Six:
Tube 2
Adding CaCl2

Calculations and Analysis:
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

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.
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:
Adding a reactant
Adding a product
Removing a reactant
Removing a product

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.

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.