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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: cseil on September 14, 2015, 10:43:09 AM

Title: Minimum work
Post by: cseil on September 14, 2015, 10:43:09 AM
Hello,
I have to identical objects at the same temperature Ti. They have the same heat capacity and it is constant with temperature.

I have to demonstrate that the minimum work that a fridge has to do in order to decrease the temperature of one of the two object to T2 is:

[tex]W_{min}=Cp[\frac{T_i^2}{T_2} + T_2 -2T_i][/tex]

I don't know how to start. This is a new problem for me.
I think I have to consider the entropy, because it's an expression that I can't get considering the adsorbed heat as Cp(T2-Ti).
I've understood that the final temperature of the other object (the one that's being heated) is 2Ti-T2.

Can you help me? Thanks