Affinity of a transformation

We shall introduce a new value - the affinity - pertaining to any transformation. The variables for this afiBnity are the (intensive or extensive) Thermodynamic variables, the quantities of material and the extent of the transformation. 

De Bonder proposed to use the term affinity of the transformation, denoted as for the entity  

According to expression [1.10], the entropy production can be expressed on the basis of that activity by  

On the basis of this definition, we shall be able to express the affinity another way. 

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The affinity of a transformation therefore depends only on the chemical potentials of the components involved in that transformation. 

The affinity of a transformation is thus the opposite of the Gibbs energy associated with that transformation. 

It can be shown, starting from the second principle of thermodynamics, that the affinity of a transformation K and its velocity r must satisfy, so that the transformation is possible, the following De Donder inequality ... 

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