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Chapter 19: Problem 25

Indicate whether each statement is true or false. (a) The second law of thermodynamics says that entropy is conserved. (b) If the entropy of the system increases during a reversible process, the entropy change of the surroundings must decrease by the same amount. (c) In a certain spontaneous process the system undergoes an entropy change of \(4.2 \mathrm{J} / \mathrm{K} ;\) therefore, the entropy change of the surroundings must be \(-4.2 \mathrm{J} / \mathrm{K}\)

Short Answer

Expert verified
(a) False - The second law of thermodynamics states that the entropy of an isolated system never decreases; it either increases or remains the same during a spontaneous process, meaning that entropy is not conserved. (b) True - In a reversible process, if the entropy of the system increases, the entropy of the surroundings must decrease by the same amount for the total change to be zero. (c) False - In a spontaneous process, we cannot say that the entropy change of the surroundings is necessarily -4.2 J/K, as the total change must be positive for the process to be spontaneous.

Step by step solution

01

(a) Entropy Conservation

The second law of thermodynamics states that the entropy of an isolated system never decreases; it either increases or remains the same during a spontaneous process. This means that entropy is not conserved. Therefore, the statement is false.
02

(b) Entropy change in reversible process

In a reversible process, the total entropy change in a system and its surroundings is zero. This means that if the entropy of the system increases, the entropy of the surroundings must decrease by the same amount for the total change to be zero. Therefore, the statement is true.
03

(c) Entropy change in spontaneous process

In a spontaneous process, the total entropy change in the system and its surroundings is positive. The statement mentions that the entropy change of the system is 4.2 J/K, which means there is an increase in the system's entropy. However, we cannot say that the entropy change of the surroundings is necessarily -4.2 J/K, as the total change must be positive for the process to be spontaneous. Therefore, the statement is false.

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