Excess Gibbs energy terms Links

We consider that the solution contains ric types of cations niunbered 1, 2,. ..c,... He and at) es of anions numbered 1, 2,. ..a,. .. Ug. We shall rewrite relation [4.114] to separately introduce the terms linked to cations and anions. The excess Gibbs energy becomes ... 

Fugacity and activity are basically compositional terms. In ideal solutions they are not necessary pressure and various composition terms can be directly linked to the Gibbs energy. Real solutions have a variety of intermolecular forces, so that ideal solution models need correction factors. These corrections can be made either to the composition terms (fugacity and activity coefficients) or to the thermodynamic potentials (excess functions), and efforts to model these correction factors in mathematical terms have always been, and likely always will be, an important research field. 

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