Question

When pressure of a perfect gas is changed isothermally the change in entropy in the form of logarithm?

Answer 1

For measurable change between two states i and f ∆S =∫ifdqTAs the temperature is constant, the above equation becomes:∆S =1T∫ifdqrev =qrevTWe know thatqrev =-wrev =nRTlnVfVisubstituting the values we get:∆S =nRlnVfViWe know that for any two states, PiVi =PfVfso, VfVi=PiPf∆S =nRlnPiPf