## Reversible and irreversible

Volume: $\Delta S = nR\ln \frac{V_{2}}{V_{1}}$
Temperature: $\Delta S = nC\ln \frac{T_{2}}{T_{1}}$

SMIYAZAKI_1B
Posts: 63
Joined: Sat Aug 24, 2019 12:15 am

### Reversible and irreversible

What is the difference between reversible and irreversible pathway? Like in the equation, we use q(REV). Is it just stating that reaction is reversible or not?

Clarice Chui 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:16 am

### Re: Reversible and irreversible

With a reversible pathway, the temperature is constant, volume increases, and pressure decreases. With a reversible process, you can use delta S= rev/T. There is more work done, which can be calculated using w= -nRTln(V2/V1). With an irreversible pathway, temperature will change (decrease then increase) and the work being done will do so against constant external pressure. There is less work being done, which can be calculated using w = -P(deltaV).

Isha_Maniyar_Dis2E
Posts: 110
Joined: Thu Jul 11, 2019 12:16 am

### Re: Reversible and irreversible

To add on, you can look at the graph in the textbook to get a better idea of the work being done in reversible v/s irreversible processes. In reversible processes, we are increasing the volume little by little and allowing the external pressure to adjust to equal the internal pressure. As a result, the graph is a downward-sloping curve. The area under this curve is the work being done.

On the other hand, with irreversible processes, the volume is suddenly increased, pushing against the external pressure. As a result, the external pressure suddenly drops.

Looking at the graphs, we can see that more work is being done for reversible pathways.

Hope this helped!

Micah3J
Posts: 100
Joined: Tue Oct 08, 2019 12:16 am

### Re: Reversible and irreversible

Clarice Chui 2C wrote:With a reversible pathway, the temperature is constant, volume increases, and pressure decreases. With a reversible process, you can use delta S= rev/T. There is more work done, which can be calculated using w= -nRTln(V2/V1). With an irreversible pathway, temperature will change (decrease then increase) and the work being done will do so against constant external pressure. There is less work being done, which can be calculated using w = -P(deltaV).

So one of the obvious factors for reversible or irreversible is if there is a change in temperature? Or what are some quick ways to identify which the system is?