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Phase-Phase Partitioning


What do we predict with SMx Solvation Models

Solvation free energy Vapour pressure Partition coefficient

By combining these we can also calculate solubility, interference adsorption and membrane permeability.

Partition coefficients

Really straight forward, since we can use the difference between the two solvation energies

\[ \Delta G^\circ_{1\to2}=\Delta G^\circ_{sol\:2}-\Delta G^\circ_{sol\:1} \]

To calculate a \(K_{eq}\) from this we can use the equation

Where \(\Delta G^\circ=\Delta G^\circ_{1\to2}\)

\[ K_{eq}=\exp{\big(\frac{-\Delta G^\circ}{RT}\big)} \]

And we can simply take the log of \(K_{eq}\) to get \(\log K\)


I didn’t bother to write notes on \(\log P\), \(\log S\), membrane/water partitioning or soil/water partitioning, since he skips over a lot of the equations. I’ll likely cover a lot of the methodology in Advanced Physical Chemistry.