## Irreversible System

$\Delta S = \frac{q_{rev}}{T}$

eduardomorales5
Posts: 77
Joined: Fri Aug 30, 2019 12:15 am

### Irreversible System

How would we find the change in entropy for an irreversible system? Why would the entropy of the surroundings equal 0?

Kishan Shah 2G
Posts: 132
Joined: Thu Jul 11, 2019 12:15 am

### Re: Irreversible System

The questions would have to say isothermal irreversible, so you would use the deltaS=nRln(V2/V1) formula. The delta S obtained is the delta S of the system. For a irreversible system, the graph is a sharp vertical dip, which means the surroundings do not have time to react to this change, so the deltaS surroundings is 0, and deltaS univerise is equal to deltaS system.

jisulee1C
Posts: 149
Joined: Thu Jul 25, 2019 12:17 am

### Re: Irreversible System

Isothermal means a constant temperature, so we can use the formula ΔS = nR ln(V2/V1).Since entropy is a state function, only the initial and final states matter, not the pathway taken to get there. In this case for irreversible free expansion, the expansion is very fast therefore the surroundings don't have time to react to the entropy change of the system and since there is no time to react, delta S of the surroundings is zero and delta S of the universe = delta S of the system.