Question

Which of the following thermodynamic relation is correct ?

• A. dG = VdP - SdT
• B. dE = PdV + TdS
• C. dH = - VdP + TdS
• D. dG = VdP + SdT

Answer 1

Answer: (A)

dG = VdP - SdT

Answer 2

$d G=d H-T d S-S d T$(as $G=H-T S$ ) again, $H=U+P V$ $\therefore d H=d U+P d V+V d P$ and $d U=T d S-P d V$ Thus $d G=(T d S-P d V)+P d V+V d P-T d S-S d T$ $=V d P-S d T$