To heat 1 cup of water (250 cm^3) to make coffee, you place an electric heating element in the cup. As the water temperature increases from 19 Celsius to 60 Celsius, the temperature of the heating element remains at a constant 120 Celsius.
1) Calculate the change in entropy of the water. (Assume that the specific heat of water is constant at 4190, and ignore the heat that flows into the ceramic coffee cup itself.)
2) Calculate the change in entropy of the heating element. Treat the heating element as a heat reservoir.
3) What is the change in entropy of the system of water and heating element?
4) Is this process reversible or irreversible?