1

In an adiabatic irreversible process we know that q = 0. Now change in entropy is defined as q/T. So when q is zero, why is change in entropy not zero ?

TESLA____
  • 292
  • 2
  • 3
  • 10
  • also: http://chemistry.stackexchange.com/questions/10706/entropy-change-in-adiabatic-process?rq=1 – DavePhD Feb 20 '15 at 19:01

1 Answers1

0

The change in entropy is the reversible heat flow divided by $T$. So if the process is irreversible, you can't use the irreversible process's heat flow to find the entropy change.

Curt F.
  • 21,884
  • 2
  • 60
  • 115
  • So, how do you find entropy change in an adiabatic irreversible process ? – TESLA____ Feb 20 '15 at 18:52
  • To find the entropy change in an adiabatic irreversible process, you need to figure out (i.e., identify) a reversible path between the same pair of initial- and final equilibrium states of the system (any reversible path will suffice) and calculate the integral of dq/T for that path. For more on this, see the following link: https://www.physicsforums.com/insights/understanding-entropy-2nd-law-thermodynamics/ – Chet Miller Jul 20 '15 at 00:52