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Entropy Variation - System, Neighborhood and Universe

by jaumzaum
Tags: entropy, neighborhood, universe, variation
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Mar18-13, 10:59 AM
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P: 248
I learned ΔSuniv = ΔSsys + ΔSneib

If ΔSuniv > 0 the process is spontaneous.

But ΔS = Q/T right? Shouldn't Qsys = -Qneib? (The heat released by the system = - heat released by the neighborhood)
I cannot understand why this is wrong!

If it were the case, ΔSuniv would be always zero

Can anyone help me?

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Mar18-13, 02:01 PM
Sci Advisor
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##\Delta S=Q/T## only for reversible processes.For irreversible processes, ##\Delta S>Q/T##.

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