Hint 5.4

Some Useful Relationships

Always true:
   P V = n R T = N k T
   ΔEint = Q + W
   dW = –p dV
   ΔEint = n CV ΔT
   CP = CV + R
   γ = CP / CV

Constant T:
   ΔEint = 0
   W = n R T ln(Vf / Vi)

Constant V:
   W = 0
   Q = n CV ΔT

Constant P:
   W = –P (Vf – Vi)
   Q = n CP ΔT

Adiabatic
   Q = 0
   P Vγ = Constant

Degrees of freedom
   Translational: f = 3
   Diatomic, Rotational: f = 2
   Diatomic, Vibrational: f = 2
   Polyatomic, Rotational: f = 3
   Polyatomic, Vibrational: f varies
   CV = fR/2, CP = (f+2)R/2, γ = (f+2)/f


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