1. A liquid is slowly cooled at constant volume. Its energy decreases. The fundamental equation says that the change in entropy of the liquid, dS = dE/T, is negative. Is this in violation of the second law of thermodynamics? Why or why not?
2. Your friend claims that in any closed cyclic process, the change in entropy for the cycle must be zero because the entropy is a state function and because the beginning and endpoints of the cycle are the same. Therefore, all cyclic processes must be reversible. What is wrong with your friend's analysis? Explain.