06. Gupta, Ram B.; Johnston, Keith
P. Ion Hydration in
Supercritical Water.
Abstract
A mol. thermodn. model is presented for the prediction of the chem. potential of an ion in supercrit. water, and also the std. free energy, internal energy, and entropy of hydration. The ref. state consists of ion-water clusters in the gas phase at low pressure, contg. integer nos. of water mols. from 1 to 6. The chem. potentials of the ion-water clusters are examd. as a function of the relevant intermol. forces, i.e., van der Waals repulsive and attractive forces, hydrogen bonding between the clusters and addnl. water mols. in the bulk, and Born electrostatic solvation. The hydrogen bonding stabilizes an ion-water cluster to a much greater extent than it is destabilized by repulsive forces. Consequently, hydrogen bonding increases the mean hydration no. and the effective Born radius.
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