Chemical Thermodynamics Joule-Thompson Expansion Joule-Thompson - PowerPoint PPT Presentation

Chemical Thermodynamics

Joule-Thompson Expansion Joule-Thompson expansion depends on non-ideal  characteristics of gases. Compare NH 3 and He in a Joule-Thompson  expansion for P 1 =100 bar to P 2 =1 bar at an initial temperature of 260 K. Chemical Thermodynamics CEM 484 2

Joule-Thompson Expansion Continue comparison between NH 3 and He.  Chemical Thermodynamics CEM 484 3

Joule-Thompson Expansion Difference between NH 3 and He due to differences  in intermolecular forces. Chemical Thermodynamics CEM 484 4

Joule-Thompson Expansion Continuously repeating a Joule-Thompson  expansion is the basis for a refrigerator Chemical Thermodynamics CEM 484 5

Ideal coolant Look at intermolecular forces to determine an ideal  refrigerant. Chemical Thermodynamics CEM 484 6

C p /C v Most chemistry done at constant pressure (so C p is  typically tabulate) but most equations involve C v . Convert between C p and C v .  Chemical Thermodynamics CEM 484 7

C p /C v Relationship between C p and C v dependent on  equation of state. For an ideal gas:  Chemical Thermodynamics CEM 484 8

C p /C v For a solid block of iron:  Chemical Thermodynamics CEM 484 9