[lopkiu]

The question given is
The variation of the Joule-Thompson coefficient of air with the temperature T at p=.101 MPa is given by approximately
   JT/(K/MPa) = -1.949 +1365/T -3150/T2
The dependence on Cp,m on T at 0.101 MPa is given approximately by
   C p,m /(J/K mol) = 27.2 + 4.18 *10-3 T
Determine the rate of change of C p,m with pressure (in J/ (K MPa mol)) for air in the region of T=300 and p=0.101 MPa

I am kind of confuse about the condition given, so the pressure is constant correct?
What came out with so far is:
Cp,m= -(partial of h over partial of p at constant T)/((partial of T over partial of P at constant H))
(partial of T over partial of P at constant H)= Joule-Thompson coefficient
(partial of h over partial of p at constant T)= -Cp,m/Joule-Thompson coefficient
And then i dun know where to go or did I even start the problem of correctly?
Determine the rate of change of Cp,m does that mean take derivative of Cp/m?
I am just as confuse as hell, can someone please help me out?

[Dolphinsiu]

It seems take derivative,

dCp,m = [27.2  + 2.09*10-3 T] dT

[lopkiu]

but then how do i put the jJoule-Thompson coefficient in?
or is it extra?

[Dolphinsiu]

Very difficuit! I also don't know how to do.