- #1
kelvin490
Gold Member
- 228
- 3
Combining first and second law of thermodynamics we can get the following equation
TdS=dU-PextdV
First question: Is this equation available for irreversible process that dS≠dQ/T?
Second question:If the system temperature Tsys is smaller than the surrounding temperature Tsur, which temperature should we put in the equation? I have this question because sometimes people use Tsur instead of Tsys (e.g. https://www.youtube.com/watch?v=jsoD3oZAAXI&list=WL&index=2 , 19:45) but the equation is supposed to describe changes in the system.
TdS=dU-PextdV
First question: Is this equation available for irreversible process that dS≠dQ/T?
Second question:If the system temperature Tsys is smaller than the surrounding temperature Tsur, which temperature should we put in the equation? I have this question because sometimes people use Tsur instead of Tsys (e.g. https://www.youtube.com/watch?v=jsoD3oZAAXI&list=WL&index=2 , 19:45) but the equation is supposed to describe changes in the system.