The discussion clarifies the application of the equation ΔSsurroundings = -Qirr/T for irreversible isothermal expansions of ideal gases. It establishes that while ΔSsystem = Q/T is valid only for reversible processes, the surroundings can be treated as a reservoir where heat exchange occurs reversibly due to its uniform temperature. This is particularly applicable when the reservoir consists of a mixture of liquid and solid at the melting point, ensuring minimal temperature gradients.
PREREQUISITESStudents of thermodynamics, physics educators, and professionals in engineering fields focusing on heat transfer and thermodynamic processes.
This assumes that there are no significant temperature gradients present within the reservoir (so that the temperature of the entire reservoir is uniform) and that the reservoir temperature remains constant during the process. This can be approached in the real world by having the material in the reservoir consist of a mixture of liquid and solid at the melting point.dhtikna said:Homework Statement
I know that the equation ΔSsystem = Q/T is only valid for a reversible process but whenever i see problems involving a irreversible isothermal expansion of ideal gas, the ΔSsurroundings is taken as -Qirr/T. Why is that equation valid for surroundings, is it because the surroundings being a reservoir/sink, any heat exchange is done reversibly?
Homework Equations
ΔSsystem = Q/T