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Entropy Variation  System, Neighborhood and Universe 
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#1
Mar1813, 10:59 AM

P: 248

I learned ΔS_{univ} = ΔS_{sys} + ΔS_{neib}
If ΔS_{univ} > 0 the process is spontaneous. But ΔS = Q/T right? Shouldn't Q_{sys} = Q_{neib}? (The heat released by the system =  heat released by the neighborhood) I cannot understand why this is wrong! If it were the case, ΔS_{univ} would be always zero Can anyone help me? []`s John 


#2
Mar1813, 02:01 PM

Sci Advisor
P: 3,555

##\Delta S=Q/T## only for reversible processes.For irreversible processes, ##\Delta S>Q/T##.



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