Homework Problem 9.101


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Homework Problem 9.101

Postby elizabethrojas1G » Wed Feb 03, 2016 10:37 pm

A neat pump heats a house in winter by extracting heat from the cold outdoors and releasing it into the warm interior For the transfer of a given amount of heat. (a) How do the entropies of the interior and exterior of the house change (increase or decrease)? (b) Which change is greater? Assume that the temperatures inside and outside the house do not change. Explain your answer.

When do we know if we're supposed to use the delta S = q/t equation to find out if entropy increases or decreases? if the temperature went up, according to the equation wouldn't entropy decrease? but i understand that if the temperature went up, it would be likely that the molecules would move around more. So how do we know when we refer to the equation and when we don't?

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Re: Homework Problem 9.101

Postby Chem_Mod » Thu Feb 04, 2016 6:57 pm

delta S= q/T is most useful when the temperature of the system doesn't change instantaneously when heat is added or removed. In this case the temperature of hte room and the temperature of the outside do not instantly change when you add or remove heat. Since heat is being added added into the room, q is positive so delta S is positive. q is negative for the outside since heat is being removed so delta S will be negative.

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