(a) 1 kg of water at 300 K is brought into contact with a heat reservoir at 600 K. When the water has reached 600 K, what is the entropy change of the water? Of the heat reservoir? Of the universe? (The heat capacity of water is 1 cal/gm-K)
(b) If the water had been heated from 300 K to 600 K by first bringing it into contact with a reservoir at 400 K and then with a reservoir at 600 K, what would have been the entropy change of the universe?
(c) Explain how the water might be heated from 300 K to 600 K with almost no change of entropy of the universe.