For an irreversible process involving only pressure-volume work_____.
A. (dF)T, p <0
B. (dF)T, p = 0
C. (dF)T, p > 0
D. (dA)T, v >0
Answer: Option A.
Explanation:
Since for an spontaneous process Tds > dU+PdV
For, constant temperature and constant pressure process the above equation can be written as
d(TS−U)>PdV
⇒ d(−A)>PdV
⇒ (dF)T,P<0.
For spontaneous process.
Here the F is Gibbs free energy and A is Helmholtz free energy.
