I got this problem with a simple partial derivation that is driving me crazy, since the solution I obtain is different from the one published in the article, in which I believe.
Basically I got this equation:
V= molar volume
a(T) = a(Tc)*( 1+ k( 1-Tr^(1/2) ) )^2
a(Tc) = 0.45724 * R^2 * Tc^2 / Pc
Tc & Pc are the critical temperature & pressure respectively
k = 0.37464 + 1.54226*w - 0.26992*w^2
b=0.0778*R * Tc / Pc
Tr = T / Tc
w is the acentric factor.
Now I need to make this partial derivation:
pi = internal pressure =
Guy sorry first time I'm using latex, with this (if some one can show me the code please) I mean the partial derivation of P respect to T at constant volume.
The solution on the article is:
Could you please help me to understand how to arrive there.