Measuring the Entropy of a Substance

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Andy Liao 1B
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Measuring the Entropy of a Substance

Postby Andy Liao 1B » Sun Feb 04, 2018 12:13 am

In Chapter 9, Section 7, the book writes "S(T) = S(0) + ΔS(heating from 0 to T) = ΔS(heating from 0 to T)" and "S(T) = area under graph of CP/T against T from 0 to the temperature of interest?" What do these two expressions mean? Can someone please explain?

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Re: Measuring the Entropy of a Substance

Postby Chem_Mod » Sun Feb 04, 2018 10:02 am

These two equations are essentially the same. Temperature is always measured in units of Kelvin, and the integral is helping us find the change in entropy from 0 K to whatever is our current temperature T. Since the 3rd law of thermodynamics states we can only have 0 entropy at 0 K, we can ignore the term S(0), or entropy at 0 K, because we know it is equal to 0.

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