Thermodynamics - Entropy 7.5 through 7.8

[@Rockyrifky]

just to correct a sign mistake(@8:30), ds = dh/T-vdP/T

[@muhammadfirdauz2246]

thank you

[@europeankid98]

Noticed that too

[@salihburakselvi2174]

Is entropy the reason why the Carnot efficiency cannot be 100%?

[@danlucas8837]

For the methane question, as du/dT=Cv => du=CvdT, the integral would be Cvln(T2/T1) would you not need to covert the Cp in the table to Cv before finding the average?

[@engineeringdeciphered]

Well, it’s liquid. For liquids there’s not a different Cp and Cv value. They are the same. Delta H is the same as delta U because there’s no (or negligible) change in volume.

[@sunmichoi6888]

Thank you!

[@zaynmoaaz8504]

[@abdulrehmankhan4860]

i have a question does entropy and temp have a direct relation ??

[@engineeringdeciphered]

No. For source and sinks, they increase and decrease in entropy without changing temperature. For pure substances, entropy is listed in the property tables, and is dependent on temp, pressure, and quality. For solids and liquids entropy change is (C)ln(T2/T1). For ideal gases, the entropy function (s0) is a function of temperature, but entropy is not. You still have that (R)ln(V2/V1) term or (R)ln(P2/P1) term so its not just temperature.

[@yigitcan824]

@@engineeringdeciphered I have a little confusion here professor, I wonder if we can say _entropy_ increases with temperature increase and it decreases with temperature decrease?

[@yigitcan824]

Professor I have a little confusion here .I'd be grateful if you could clear up it. Why do we usually _underline_ *internally reversible* ? I mean what's the difference between *internally reversible* and *reversible* ?

[@cemretas9469]

internally reversible means only the *system* is reversible (inside the boundaries), reversible means both *system and its surroundings* are reversible.

[@yigitcan824]

@@cemretas9469 I see, but in the questions in the book it always say reversible but internally reversible . Maybe we're just responsible for reversible ones o for now. Thanks

[@bountyhunter4985]

💯