Write the equilibrium expression, Kc, for Reaction 4: H2 + I2 ⇌ 2HI
(Hint: Because of the coefficient “2” in front of HI, you will have to square the concentration of HI to find Kc.)

Kc= [ ]2 [ ]

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3




Similarly to how you gathered data in #3, collect data at least 10 times and average your results to get the best approximation of Kc. Choose your own initial number of moles (DO NOT CHOOSE ZERO!), but make sure to gather the Concentration on the Bar Chart and Graph.
Mol H2
Mol I2
Mol HI
Initial
[H2]
Initial
[I2]
Initial
[HI]
Eq. [H2]
Eq. [I2]
Eq. [HI]
Kc










































































































































































































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10






Question
Answer
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7.
What is the average Kc for this reaction?


1




Activity C:
Reaction direction
Get the Gizmo ready:
Click Reset. Check that Reaction 4 is selected.
Set Moles H2 to 1, Moles I2 to 1, and Moles HI
to 7.



Introduction: For a reversible reaction with equilibrium constant Kc, it often is useful to know in which direction the reaction will proceed given the starting amounts of reactants A and B and products C and D. This is done by calculating the reaction quotient, Qc:



Question: How can you predict the direction of a reversible reaction?
List: Select the BAR CHART tab. What are the initial concentrations of each substance?

Substance
Initial Concentration
H2


I2


HI




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3




Calculate: Use your values from #1 to solve for Q.
Qc= [ ]2 [ ]

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3






Question
Answer
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B.
What is the current value of Qc?


1


C.
In activity B, question #7A what value of Kc did you arrive at for this reaction?


1


D.
How does Qc compare to Kc?


2




Analyze: Recall that Qc is equal to the ratio of product concentrations to reactant concentrations.



Question
Answer
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A.
If there is an excess of products, will Qc be greater than or less than Kc?


1


B.
If there is an excess of reactants, will Qc be greater than or less than Kc?


1


C.
In the current situation, is there an excess of products or reactants? Explain:


2


D.
When the reaction begins, do you expect [HI] to increase or decrease? Explain:


2




Test: Click Play.



Question
Answer
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What happens to [HI]?


1




Conclusion:
Question
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Scripture says, “Do you know the balancings of the clouds, the wondrous works of Him who is perfect in knowledge?”. God has shown some of His glory to humans as they discover His amazing world. As you think about the equilibrium of concentrations, can you see how He has balanced the various components of our world? Does that prove that He not only created it but sustains it as well? Please give your thoughts.


4




Discuss the Hypotheses - Look back at hypotheses you wrote on page 1.


Answer
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Earned
What were your hypotheses and were they correct? (minimum 2-3 sentences)


3


How do you know your hypotheses were correct or incorrect? Use relevant data/observations to support your answer. (minimum 3-5 sentences)


7




Discuss the Goals - Form a summary statement for each goal, showing you understand and have met the goals of this lab. Be sure to explain all major concepts and relationships presented in this lab. (minimum 3-5 sentences each)


Answer
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Earned
Explain why a reversible chemical reaction eventually reaches equilibrium.


10


Determine the equilibrium constant Kc and the reaction quotient Qc for a reversible reaction.


Predict the direction of a reaction based on Qc and Kc.