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Entropy Chapter 9 #7

Posted: Wed Jan 25, 2017 7:42 pm
by Jonathan Orozco 1A
Hello everyone i was wondering any one could send me in the right direction as to which formula to use for question #7 chapter 9.

Question #7: Assuming that the heat capacity of an ideal gas is independent of temperature, calculate the entropy change associated with raising the temperature of 1.00 mol of ideal gas atoms reversibly from 37.6 C to 157.9 C at (a) constant pressure and (b) constant volume.

Thank you in advance, and have a great day!

Re: Entropy Chapter 9 #7

Posted: Wed Jan 25, 2017 10:25 pm
by Daniel Dobrin 2F
You would use basically the same formula for both parts of the question.
For constant pressure, use:
Delta S = n*Cp*ln(T2/T1), where Cp signifies a constant pressure.

For constant volume, use:
Delta S = n*Cv*ln(T2/T1), where Cv signifies a constant volume.

Since it tells us we're dealing with ideal gas atoms, we're gonna change the Cp and Cv. On the formula sheet, it says that for monatomic ideal gases, Cp = 5/2*R and Cv = 3/2*R, where R is the gas constant (8.314 J/K/mol).

Hope this helps! :)