Pistons and Reversibility

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Payton Kammerer 2B
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Pistons and Reversibility

Postby Payton Kammerer 2B » Sun Feb 09, 2020 11:12 pm

In the sixth edition of the textbook, one of the practice problems describes a situation in which a gas is compressed with a piston, but says that this compression is irreversible, and asks to calculate the entropy. This question confuses me for two different reasons, 1) isn't entropy a state function, so the reversibility shouldn't be relevant? and 2) isn't the whole point of a piston that the compression is reversible?

Thanks!

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Re: Pistons and Reversibility

Postby Chem_Mod » Mon Feb 10, 2020 4:18 pm

1. Yes, you are correct. Entropy is a state function so it does not matter whether it is reversible or irreversible
2. Not necessarily; pistons you might use in daily life, sort of like syringes for example, do not compress reversibly


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