Empirical Estimates of Standard State Entropy

As shown by Helgeson et al. (1978), satisfactory estimates of standard state molar entropy for crystalline solids can be obtained through reversible exchange reactions involving the compound of interest and an isostructural solid (as for heat capacity, but with a volume correction). Consider the generalized exchange reaction 

For nonisostructural solids, satisfactory estimates can be obtained with the method proposed by Fyfe et al. (1958)  

Holland (1989) reconsidered the significance of constant K in fight of Einstein s model for the heat capacity of solids (see eq. 3.35 and 3.45)  

MgSiOg + MnO MnSiOj + MgO CaSi03 + MnO MnSiOj + CaO CaMgSi20g MgSi03 + CaO + Si02  

H20(a) = diaspore, gibbsite, serpentine, dioctahedral micas H20(b) = chlorites, talc, trioctahedral micas, amphiboles 

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