Free energy
A. Decreases in all spontaneous (or irreversible) processes
B. Change during a spontaneous process has a negative value
C. Remains unchanged in reversible processes carried at constant temperature and pressure
D. All of the above
Answer: Option D
Solution (By Examveda Team)
Since for an spontaneous process $$s > dU + PdV$$For, constant temperature and constant pressure process the above equation can be written as
$$\eqalign{ & d\left( {TS - U} \right) > PdV \cr & \Rightarrow d\left( { - A} \right) > PdV \cr & \Rightarrow {\left( {dG} \right)_{T,P}} < 0. \cr} $$
For spontaneous process (irreversible). And $${\left( {dG} \right)_{T,P}} = 0$$ for, a reversible process.
This Question Belongs to Chemical Engineering >> Chemical Engineering Thermodynamics
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