# Chemical Thermodynamic Functions [closed]

I'm a high school student with basic knowledge about chemical thermodynamics. I have three questions regarding the thermodynamic state functions $H, S, G$. I have searched a lot in textbooks but they don't give the complete information as to whether the properties taken are that of the system or surroundings.

Q1):-Enthalpy is given by the formula

$H = U +PV$ . What I want to know is that whether $P$ mentioned above is the internal pressure of the system or the externally applied pressure?

Q2):- The change in entropy is given by the formula $\Delta S= $$\int_1^2$${\frac{dq_{reversible}}{T}}$. Is the temperature mentioned of the system or the surroundings.

Q3)-On the same lines what temperature is taken to define the Gibbs free energy function:-$G=H-TS$.

## closed as too broad by Mithoron, Jan, NotEvans., pentavalentcarbon, TyberiusSep 8 '17 at 14:35

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