Entropy Equation
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Lindsay H 2B
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Entropy Equation
In my notes from the lecture a few weeks ago on wednesday 1/24 I have written that ∆S=-nRTln(V2/V1) but the solutions manual and the book both use that equation without the negative sign. Can anyone explain why that is?
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Chem_Mod
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Re: ∆S=nRTln(Vf/Vi)
The equation you wrote down is actually the equation for work. Please see Dr. Lavelle's constants and equations sheet on his website for clarification. https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf
Also note that there is no T variable in the equation for
when there is a volume change.
Also note that there is no T variable in the equation for
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Chem_Mod
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Re: ∆S=nRTln(Vf/Vi)
Your expression is indeed that for work, not change in entropy. But this is a matter of going through the derivation.
Under an isothermal process,
, so that
Work under an isothermal reaction is
)
And change in entropy, with constant temperature, is
Substitute w for q in the above equation
Substitute the expression of W under an isothermal process for
)
The final equation is how you would calculate the change in entropy for an isothermal process.
Under an isothermal process,
, so that
Work under an isothermal reaction is
And change in entropy, with constant temperature, is
Substitute w for q in the above equation
Substitute the expression of W under an isothermal process for
The final equation is how you would calculate the change in entropy for an isothermal process.
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