6. You make tea with 0.30 kg of 95°C water and for some inexplicable reason let it cool to room
temperature (20°C) before drinking it. 

(a) Calculate the entropy change of the water while it cools. 

(b) The cooling process is essentially isothermal for the air in your kitchen. Calculate the change
in entropy of the air while the tea cools, assuming that all the heat lost by the water goes into
the air. What is the total entropy change of the system tea + air?

(c) The next day you make the same tea. But this time, rather than let it sit in your room
temperature kitchen until it has reached 20°C, you put it in a 95°C oven. Then you oh-so-
gradually reduce the temperature inside your oven until both the oven and the tea are at 20°C.
Calculate the entropy change of the tea and the entropy change of the air inside the oven as a
result of the cooling of the tea. (Pay no attention to whatever mechanism is used to cool the
oven. You are concerned only with the interaction of the tea and the air inside the oven.)