1. Thermodynamic Property Relations
Chapter 12

2. The Maxwell Relations
The equation that relate the partial derivatives of properties P, v, T and s of a simple compressible system to each other are called the Maxwell relations.
They are obtained from the four Gibb equation, expressed as:

3. The Maxwell Relations are

4. The Clapeyron Equation
This equation enables us to determine the enthalpy change associated with a phase change from a knowledge of P, v and T data alone.

5. The Clapeyron – Clausius Equation
For liquid – vapor and solid – vapor phase change processes at low pressures, it can be approximated as

6. General Relations
Internal Energy Changes

7. Enthalpy Changes

8. Entropy Changes

9. Specific Heats Cv and CP

10. Volume Expansivity (β) & Isothermal Compressibility (α)

11. The Joule – Thomson Coefficient
It is a measure of the change in temperature of a substance with pressure during a constant enthalpy process, and it can be expressed as

13. The enthalpy departure can be expressed as:

14. Similarly

15. EXAMPLE