With respect to 1 kg of liquid water:
(a) Initially at 0°C, it is heated to 100°C by contact with a heat reservoir at 100°C. What is the entropy change of the water? Of the heat reservoir? What is ΔS_total?
(b) Initially at 0°C, it is first heated to 50°C by contact with a heat reservoir at 50°C and then to 100°C by contact with a reservoir at 100°C. What is ΔS_total?
(c) Explain how the water might be heated from 0°C to 100°C so that ΔS_total = 0.