1. Chapter 3 – Enthalpy and Internal Energy: The Importance of State Functions

2. Let’s examine the pressure of any system as a function of T and V

3. For a fluid system or a solid Isothermal Compressibility

4. For solids and fluid systems The coefficient of thermal expansion

5. Assume that we will write pressure as a function of T and V

6. In general, we write U as a function of T and V

7. Examine the second partial derivative

8. A T 1, V m,1, P 1 B Stirrer Valve Thermal insulation FF OO C O C O 50 40 30 20 10 0 20 30 40 50 120 100 80 0 20 40 60 40

9. The partial derivative is known as the Joule coefficient,  J.

10. The change in the internal energy under isothermal conditions is related to the Joule Coefficient

11. For an ideal gas In general

12. In general, we write H as a function of T and P

13. Define the constant pressure heat capacity, C P

14. Examine the second partial derivative

15. Porous Plug Thermal insulation T 1, P 1, V m,1 T 2, P 2, V m,2 FF OO C O C O 50 40 30 20 10 0 20 30 40 50 120 100 80 0 20 40 60 40 FF OO C O C O 50 40 30 20 10 0 20 30 40 50 120 100 80 0 20 40 60 40

16. The partial derivative is known as the Joule-Thomson coefficient,  JT.

17. The change in the enthalpy under constant pressure conditions is related to the Joule-Thomson Coefficient