Raoultian and henrian models linearize some nonlinear parameter, regular solution model introduce an \alpha factor for thermodynamic activity coefficient. Is it possible to derive parameters of such thermodynamic models, e.g. henrian interaction coefficient between three elements, from first principle? namely electronic structure of materials, statistical mechanics, and state function-process variables of elementary thermodynamics?
As for the ideal solution model, entropy and enthalpy of mixing both are taken to be zero. for regular solution model, entropy of mixing is zero but enthalpy of mixing is nonzero.
I have heard of CALPHAD, but less so of VASP. But what are the principles of equations behind these formula ? Say , if I want to find henrian activity coefficient of carbon in molten iron, which equations of transport phenomena, statistical mechanics and quantum mechanics (among many others) be required?
Yes, it is possible,
do you know the metodologies; CALPHAD and VASP ?
I have heard of CALPHAD, but less so of VASP. But what are the principles of equations behind these formula ? Say , if I want to find henrian activity coefficient of carbon in molten iron, which equations of transport phenomena, statistical mechanics and quantum mechanics (among many others) be required?
Let me first clarify one point: in the ideal and regular solution models the entropy of mixing is assumed to follow the ideal mixing rule; it is not zero. What is done is that the Gibbs energy of the ideal solution model is taken as a reference. All non-idealities are then in the excess Gibbs energy (in excess of the ideal Gibbs expression). So, indeed in the regular solution model the excess entropy is zero and there is only an excess enthalpy. Once the excess Gibbs energy is defined, activity coefficients, Henry coefficients and other quantities follow.
There are lots of models around for excess Gibbs energy models, depending on the class of molecules one is after. Some derive from statistical mechanical models others are correlations found to fit well to properties of classes of molecules.
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