(a) Does the entropy of the surroundings increase for spontaneous processes? (b) In a particular spontaneous process the entropy of the system decreases. What can you conclude about the sign and magnitude of $\Delta S_{\text {surr }} ?$ (c) During a certain reversible process, the surroundings undergo an entropy change, \(\Delta S_{\text {surt }}=-78 \mathrm{~J} / \mathrm{K} .\) What is the entropy change of the system for this process?

(a) For spontaneous processes, the overall entropy change in the universe must be positive. If the entropy of the system decreases but the entropy of the surroundings increases by an even larger amount, the total entropy change will still be positive, and the process will be spontaneous. (b) Since the given process is spontaneous and the entropy of the system decreases, the entropy change of the surroundings (∆S_surr) must be positive and greater in magnitude than the decrease in entropy of the system. (c) In a reversible process, the total entropy change in the universe is zero. Given ∆S_surr = -78 J/K, we can conclude that the entropy change of the system, ∆S_sys, is positive and equal in magnitude: \(\Delta S_{\text {sys}} = 78 \mathrm{~J} / \mathrm{K}\).