1. Thermodynamics

2. System / environment

3. Diathermal / adiabatic Walls between the system and surroundings are called diathermal if they permit energy flow in or out

4. Diathermal / adiabatic Adiabatic walls do not permit any energy flow (perfect insulators)

5. Q, W, U HEAT WORK INTERNAL ENERGY

6. Ways to change U ΔU ΔU Q W

7. Energy added as heat can be used to do work Q ΔUΔU W

8. Energy added through work can be released as heat Q ΔUΔU W

9. Laws of TD 1) You can’t win. 2) You can’t break even. 3) You can’t quit.

10. 0’th Law Energy flows from an object with a higher T to the object with a lower T… NATURALLY

11. First Law of Thermodynamics You can’t win… energy does not just ‘come out of nowhere’

12. Isobaric process: P = const

13. Isobaric graph Amount of work done

14. Example 1

15. 3 “ISOS-” and “ADIA-” Isobaric – a thermodynamic process that takes place at a constant pressure Isochoric – a thermodynamic process that takes place at a constant volume Isothermal - a thermodynamic process that take place at a constant temperature Adiabatic - a thermodynamic process in which Q = 0

16. Isochoric graph

17. Isochoric

18. Isothermal

20. Adiabatic

22. Thermodynamic processes: Isothermal T = const ΔU Isochoric V = const W Adiabatic Q Isobaric P=const

23. Isochoric process 1 st Law of Thermodynamics

24. Isothermal 1 st Law of Thermodynamics Note : in case of phase change internal energy changes even if temperature does not.

25. Adiabatic 1 st Law of Thermodynamics

26. Isolated system NO CHANGE IN INTERNAL ENERGY

27. Heat Engine

29. Step 1 – intake

30. Step 2 – compression. U is increased by work done on the mixture

31. Power / work step – due to combustion the gas is doing work pushing the piston down.

32. Exhaust – gas (and the ‘left over’ energy) is pushed out)

33. Efficiency of a Carnot Engine

35. a) U increases through heat b) U increases through work c) U decreases through heat d) U decreases through work

37. 2 nd Law of Thermodynamics

38. Entropy – the measure of a system’s disorder 2 nd Law: All natural processes lead to increase of entropy of the universe.

39. 3 rd Law of Thermodynamics It is not possible to lower the temperature of any system to absolute zero.