QuestionReal gases / Joule–Thomson effect
In the Joule-Thomson expansion of real gas at inversion temperature, the Joule-Thomson coefficient:
- (a) will be negative if the gas cools post expansion
- (b) will be positive if the gas gets heated post expansion
- (c) will be zero if [∂(PV)/ ∂P]T is positive
- (d) is zero
Answer: (d) is zero
μJT = (∂T/∂P)H. At the inversion temperature, μJT changes sign, so μJT = 0 → (d). Below Ti gas cools (μ > 0); above it heats (μ < 0). (a) and (b) have the sign rules reversed.