2. Thermodynamics Dr. Feng Song Photonics Center, College of Physics Sciences http://physics.nankai.edu.cn/grzy/fsong.htm fsong@nankai.edu.cn Third Version Copyright @ 2007

3. It is just the third edition for this powerpoint.

4. I hope that there are some students who are good at computer and interested in physics to help me to upgrade the software.

5. Thanks in advance

6. Temperature Thermodynamic system Classification State parameters Equilibrium Zeroth Law Temperature Temperature scales

7. Thermodynamic System Definition: Limited-sized system containing numerous particles. Environment (opposite to system)

8. Classification: Closed System----no mass exchange, no energy transfer Open System Isolated System---no energy transfer, no mass exchange Adiabatic System---no heat exchange

9. State Parameters of a system – Geometric – Mechanical – Chemical – Electro-magnetic – Thermal: Temperature

10. Equilibrium Equilibrium State – No change for the state parameters – Stable state Thermal Equilibrium – Temperature unchanged, no heat transfer

11. Zeroth Law If system A and B are each in thermal equilibrium with a third system C, then A and B are in thermal equilibrium with each other

12. Temperature When two system are in thermal equilibrium, they have the same temperature The system are in thermal equilibrium IF AND ONLY IF they have the equal temperatures

13. Temperature is a scalar quantity, which is a property of all thermodynamic system in equilibrium One of the seven basic units of International System of Units(SI)

14. Temperature Scale Empirical Temperature Scale – Celsius,Kelvin, Fahrenheit,… – Ideal Temperature Scale Ideal Temperature Scale Thermodynamic Temperature Scale International Temperature Scale

15. Empirical Temperature Scale Three factors – Thermometric substance and property X Volume, pressure… – Function between temperature T and X T=aX+b, T=aX,… – Calibration points Boiling point, triple point…

16. Empirical Temperature Scale Celsius Temperature Scale – Mercury, volume or pressure – t=aX+b – 0 degree for ice-water, 100 for boiling point of water

17. Empirical Temperature scale Fahrenheit Temperature Scale – Mercury, volume or pressure – t=aX+b – 0 degree for ice-salt water, 212 for boiling point of water

18. Empirical Temperature Scale Kelvin Temperature Scale – X=volume V or pressure P of a gas – T=aX – Ttr=273.16K for triple point of water – T=273.16* X/Xtr

19. Ideal temperature scale t=T(K)-273.15 ( 0 C)

20. Equation of State State parameters ~Temperature

21. Equation of State Thermal Expansion Equation of State for an ideal gas Equation of state for mixed ideal gases Equation of state for mixed ideal gases Equation of state for real gases Microscopic Approach to the Thermodynamic System Microscopic Approach to the Thermodynamic System

22. Thermal Expansion Cubic expansion coefficient Isochoric pressure coefficient

23. Isothermal compression coefficient Relations between the three coefficients

24. Equation of State for an ideal gas Boyle-Marriot Law: PV=P*V*  PV= RT=NkT P=nkT =M/   M: the mass, N:number of total molecules  :mole mass  number of moles n:number density of the gas

25. Useful Constant Universal gas constant R=kN A =8.31J/mol.K Avogadro constant N A =6.02*10 23 molecules/mole Boltzman constant k=1.38*10 -23 J/K

26. Equation of state for mixed ideal gases The mixture of gas have a volume V and a pressure P.

27. Volume percentage When the gases keep the same pressure, they have the volume V 1, V 2 … and the total volume is: V=V 1 +V 2 +… The volume percentage is: V i /V

28. Dalton Law When the gases keep the volume of V, they have pressure P1,P2,… and then:P=P1+P2+…

29. Average mole mass, number of moles for the mixed gases  =M/ =M 1 /  1 +M 2 / 2 +…

30. Equation of state for real gases Van Der Waals equation (P+a/V 2 )(V-b)=RT – a and b are constants whose values must be obtained by experiments

31. Virial Expansion and Onnes Equation The virial coefficients must be found emperically, by fitting the equation to experimental data

32. Microscopic Approach to the Thermodynamic System A system consists of particles The particles are in random motion and obey Newton’s law of motion There is interaction between the particles

33. Macroscopic quantities are statistic results from microscopic quantities

34. Thanks Have a good week