solutions manual chapter 17
CHAPTER 17
SPONTANEITY, ENTROPY, AND FREE ENERGY
Questions
11.
Living organisms need an external source of energy to carry out these processes. Green plants use the energy from sunlight to produce glucose from carbon dioxide and water by photosynthesis. In the human body, the energy released from the metabolism of glucose helps drive the synthesis of proteins. For all processes combined, ∆Suniv must be greater than zero
(the second law).
12.
Dispersion increases the entropy of the universe because the more widely something is dispersed, the greater the disorder. We must do work to overcome this disorder. In terms of the second law, it would be more advantageous to prevent contamination of the environment rather than to clean it up later. As a substance disperses, we have a much larger area that must be decontaminated.
13.
As a process occurs, ∆Suniv will increase; ∆Suniv cannot decrease. Time, like ∆Suniv, only goes in one direction.
14.
This reaction is kinetically slow but thermodynamically favorable (∆G < 0). Thermodynamics only tells us if a reaction can occur. To answer the question will it occur, one also needs to consider the kinetics (speed of reaction). The ultraviolet light provides the activation energy for this slow reaction to occur.
15.
Possible arrangements for one molecule:
1 way
1 way
Both are equally probable.
Possible arrangements for two molecules:
1 way
2 ways, most probable
655
1 way
656
CHAPTER 17
SPONTANEITY, ENTROPY, AND FREE ENERGY
Possible arrangement for three molecules:
1 way
3 ways
3 ways
1 way
equally most probable
16.
∆Ssurr = !∆H/T; heat flow (∆H) into or out of the system dictates ∆Ssurr. If heat flows into the surroundings, the random motions of the surroundings increase, and the entropy of the surroundings increases. The opposite is true when heat flows from the surroundings into the system (an endothermic reaction). Although the driving force described here really results from the change in entropy of
SPONTANEITY, ENTROPY, AND FREE ENERGY
Questions
11.
Living organisms need an external source of energy to carry out these processes. Green plants use the energy from sunlight to produce glucose from carbon dioxide and water by photosynthesis. In the human body, the energy released from the metabolism of glucose helps drive the synthesis of proteins. For all processes combined, ∆Suniv must be greater than zero
(the second law).
12.
Dispersion increases the entropy of the universe because the more widely something is dispersed, the greater the disorder. We must do work to overcome this disorder. In terms of the second law, it would be more advantageous to prevent contamination of the environment rather than to clean it up later. As a substance disperses, we have a much larger area that must be decontaminated.
13.
As a process occurs, ∆Suniv will increase; ∆Suniv cannot decrease. Time, like ∆Suniv, only goes in one direction.
14.
This reaction is kinetically slow but thermodynamically favorable (∆G < 0). Thermodynamics only tells us if a reaction can occur. To answer the question will it occur, one also needs to consider the kinetics (speed of reaction). The ultraviolet light provides the activation energy for this slow reaction to occur.
15.
Possible arrangements for one molecule:
1 way
1 way
Both are equally probable.
Possible arrangements for two molecules:
1 way
2 ways, most probable
655
1 way
656
CHAPTER 17
SPONTANEITY, ENTROPY, AND FREE ENERGY
Possible arrangement for three molecules:
1 way
3 ways
3 ways
1 way
equally most probable
16.
∆Ssurr = !∆H/T; heat flow (∆H) into or out of the system dictates ∆Ssurr. If heat flows into the surroundings, the random motions of the surroundings increase, and the entropy of the surroundings increases. The opposite is true when heat flows from the surroundings into the system (an endothermic reaction). Although the driving force described here really results from the change in entropy of