
#1
Nov2011, 06:37 AM

P: 5

Hey guys,
I'm working on calculating the enthalpy, entropy and internal energy of substances. treating them as an ideal gas. I wonder if I could be pointed in the right direction with some calculations. Enthalpy change: h_{2}h_{1}=∫c_{p} dT+ ∫[vT(∂v/∂T)_{P}]dP At ideal gas the pressure integral goes to zero. So we have just the integral of C_{p} with respect to T. All correct so far? Its with the entropy and internal energy where I get confused. ds = (C_{p})dT  (∂v/∂T)_{P} dP is there a way to simplify this further at ideal gas to make it easily calculated ? I guess internal energy can be calculated from h using h = u + Pv. Thanks very much Look forward to any replies. 1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution 



#2
Nov2011, 08:15 AM

Sci Advisor
HW Helper
P: 6,564

So, if pressure is constant, ∫VdP = 0, so ΔH = ΔQ = ∫C_{p}dT So you can use: dH = TdS + VdP AM 


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