Which of the following thermodynamic relation is correct ?

1.	Which of the following thermodynamic relation is correct ?
Answer» `dG =V d p -SdT` `DE = P DV + T dS` `dH = - V dP +T d S` `Dg= vDp+ S dT` Solution :`G= H - TS ` But `H =U + PV` `:. G= U + PV - TS` Differentiating it completely ,we GET `dG=dU +PdV+ VdP - TdS - SdT`…(i) But `dU =DQ+dw` and `w= -PdV` `:. dU = d-PdV` or `dq = dU+ PdV`…(ii) Further, for averversible process, `dS= ( dq)/(T)` or `dq=TdS`....(iii) From (ii)and (iii), `dU +PdV=T DeltaS` Substituting this in (i),weget`dG =VdP - SdT`

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