1. The formation of water from its elements at 1200 K can be written as a series of
coupled reactions: (1 point)
Suppose the system has the following concentrations:
[H2] = 0.0041 M
[O2] = 0.0062 M
[H2O] = 2.3 M
Pr
...
1. The formation of water from its elements at 1200 K can be written as a series of
coupled reactions: (1 point)
Suppose the system has the following concentrations:
[H2] = 0.0041 M
[O2] = 0.0062 M
[H2O] = 2.3 M
Predict the direction in which the system will shift to reach equilibrium. Justify your
answer.
Answer: With these concentrations that are given, the equilibrium direction will shift to
the right. This is because if more product is added to a reaction, the equilibrium will shift
to the right to be in favor of the reactants.
3.1.7 Practice: General Equilibrium Practice
AP Chemistry Sem 2
Points Possible:25 Name: Rodolfo Marquez Valencia
Date: 3/15/20212. The figure below shows two possible methods for the production of acetyl CoA from
acetate as part of the biosynthesis of fatty acids in the body. The first method is a direct
reaction, and the second method involves coupled reactions.
Direct Reaction
Coupled Reactions
Step 1
Step 2
a. The standard Gibbs free energy for the direct reaction, ΔG°', is 32 kJ/mol. (Note that
the prime symbol is used for biological systems.) Calculate the equilibrium constant forthe reaction at a temperature of 298 K. Is the reaction favorable or unfavorable?
Explain. (1 point)
Answer: Kc = 2.46 * 10-6, ∆Gº > 0 ; Therefore, the reaction is not favorable because it is
an endergonic reaction, meaning that the process needs some type of energy added to
move forward and create a reaction.
b. Calculate the equilibrium constant for each step of the coupled reactions. ΔG1°' is
about 11 kJ/mol for the first reaction, and ΔG2°' is about –10 kJ/mol for the second
reaction. Is each step favorable or unfavorable? Explain. (1 point)
Kc = 0.012, ∆Gº > 0 ; Therefore, the reaction is not favorable because it is an
endergonic reaction which requires added energy to proceed.
Kc = 56.6, ∆Gº < 0 ; Therefore, the reaction is favorable because it is an exergonic
reaction which releases energy and the reactants have more energy than the products.
c. Determine the net reaction for the coupled reaction, its Gibbs free energy value, and
its overall equilibrium constant. (1 point)
Answer: Acetyl CoA net reaction; Kc = 0.67, ∆Gº > 0 ; The reaction is not favorable.d. Predict whether the direct method or the coupled reaction method would be more
likely to occur in the body to produce acetyl CoA from acetate. What might happen to
make the reaction even more likely to occur? (1 point)
Answer: Acetyl CoA is produced much easier through the coupled reaction method.
Metabolic pathways make it more likely to occur because they are favored when acetate
concentrations increase.
3. The decomposition of copper(I) oxide to produce copper is unfavorable at a certain
temperature. (1 point)
When the reaction is coupled with the oxidation of carbon to produce carbon monoxide,
however, the production of copper from copper(I) oxide is favorable.
Explain why this is possible.
Answer:
Kc = [CS2][H2]4 / [CH4][H2S]2
Kc = a*(4a)4/[(0.5-a)(0.75-a)2]
a = 0.44/4 —> 0.11 M
Kc = 3.8*10-2
This is possible because ∆G depends on the ∆H and ∆S. So, if ∆H < 0 and ∆S > 0, the
reaction is favorable.4. Carbonyl bromide decomposes to produce carbon monoxide and bromine gas
according to the foll
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