7th edition 4F.11

Volume:
Temperature:

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chloewinnett1L
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Joined: Fri Sep 28, 2018 12:20 am

7th edition 4F.11

Postby chloewinnett1L » Sat Feb 09, 2019 5:58 pm

I'm confused as to why the solutions manual doesn't indicate that you use (5/2)R instead of R when calculating the entropy change of non-isothermal irreversible expansion. Isn't the pressure kept constant? And the gas should be assumed ideal?

Chem_Mod
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Re: 7th edition 4F.11

Postby Chem_Mod » Sun Feb 10, 2019 2:40 am

Please post the question too so we can better assist.

Theodore_Herring_1A
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Re: 7th edition 4F.11

Postby Theodore_Herring_1A » Mon Feb 11, 2019 4:42 pm

The question is,

"During the test of an internal combustion engine, 3.00 L of nitrogen gas at 18.5°C was compressed suddenly (and irreversibly) to 0.500 L by driving in a piston. In the process, the temperature of the gas increased to 28.1°C. Assume ideal behavior. What is the change in entropy of the gas?".

The answer key shows using the formula: deltaS = nRln(T2/T1), rather than: deltaS = n(R*5/2)ln(T2/T1). Is this a viable formula?

chloewinnett1L
Posts: 55
Joined: Fri Sep 28, 2018 12:20 am

Re: 7th edition 4F.11

Postby chloewinnett1L » Wed Mar 13, 2019 1:02 am

Still have this question. Is it possible to use R instead of C when calculating the entropy of reversible isobaric compression due to change in temperature, as the solution manual says?

tierra parker 1J
Posts: 61
Joined: Fri Sep 28, 2018 12:17 am

Re: 7th edition 4F.11

Postby tierra parker 1J » Thu Mar 14, 2019 1:52 pm

is it because the pressure is also changing that you can't use the nCln(T2/T1) equation?


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