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II. Indicate whether each statement is true or false. (a) All spontaneous processes are irreversible. (b) The entropy of the universe increases for spontaneous processes. (c) The change in entropy of the surroundings is equal in magnitude and opposite in sign for the change in entropy of the system, for an irreversible process. Briefly explain. (d) The maximum amount of work can be gotten out of a system that undergoes an irreversible process, as compared to a reversible process. Briefly explain.
Expert Answer
(a) True
Spontaneous processes are irreversible because they can be reversed only by taking a different path to get back to their original state.
(b) True
In any spontaneous process, the entropy of the universe increases.
Suniv =
Ssys +
SSurr the change in entropy of the universe is the sum of the change in entropy of the system and the change in entropy of the surroundings.
(c) False
For a reversible case, the entropy change of the surroundings is equal in magnitude, but opposite in sign to the entropy change of the system, and the entropy change of the universe (the sum of the entropy changes of the system and surroundings) is zero.
(d) False
In general, energy released by a reversible process can do the maximum amount of work because less of the energy is lost as heat. A process that is done quickly (irreversibly) tends to generate turbulence and friction resulting in heat loss to the surroundings.
Entropy is not conserved: Suniv is increasing.
For a reversible process: Suniv = 0.
For a spontaneous process (i.e. irreversible): Suniv > 0.
(c)
