Effects of ionic strength on biochemical reaction thermodynamics

Defining enthalpy and entropy of formation according to the definition of Gibbs free energy, we have 

If the standard enthalpies of formation for the species are known and assumed to remain approximately constant (over some range of temperature), then Equation (2.26) yields the following expression for calculating A fG° as a function of temperature  

Given information on the standard enthalpies of formation for the species in a reaction, this expression may be used to estimate the standard free energies of formation at one temperature T2 as functions of the values of A fG° at another temperature 7).5 The temperature-corrected estimates of A fG° yield temperature-corrected estimates of ArG° through Equation (2.23). This ability to correct for temperature is important because the majority of biochemical reaction data are tabulated at 25°C, while human beings and many other warm-blooded creatures operate at temperatures near 37°C. 

5 Effects of ionic strength on biochemical reaction thermodynamics 

Because the energy associated with solvation depends on the ionic properties of the solution, the values of A fG° depend on the ionic properties of the solution. This phenomenon is formally accounted for by defining the activity of species i as 

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