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Physical & Chemical properties

Dissociation constant

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The dissociation constant is a constant describing the equilibrium of the dissociation of a compound in its different existing chemical forms in solution. Dissociation constants are normally measured at different dilutions. In the literature, the compiled values are those obtained after extrapolation to infinite dilution. To be able to calculate the dissociation constant, it is necessary to know the concentrations or activities of all chemical forms participating in the equilibrium.  In the case of MEA Polyborate, the substance exists in a whole range of rapidly interchanging chemical forms giving several overlapping non resolved signals in NMR and IR spectroscopy. Any interference by diluting or trying to measure the concentration of one of the entities by chemical means will immediately shift the existing equilibrium.  Therefore it is impossible to obtain a reliable dissociation constant for the MEA-Polyborate.  Further, water is also part of the composition of MEA-Polyborate, but it is impossible to discriminate between water taking part in the reaction and water acting as solvent, again precluding measuring the constant reliably. Conclusion: It is impossible to obtain a reliable dissociation constant due to rapidly interchanging forms and participation of water in the reaction equilibrium.

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