At room conditions, and in absence of any electric field, the dissociation constant of water is Keq= 10-14 mol2 L-2. What means that, statistically, [H+] = [OH-] = 10-7 mol L-1. I have found general comments indicating that in presence of fields about 2·109 Vm-1 water is almost fully dissociated. I woud appreciate a proper reference showing a relationship between Keq and the electric field.
Is the dissociation energy a function of field strength or independent?
I believe that the dissociation energy is unique, and independent of field strength
Thanks you for your interest and questions/comments. Let's assume that the dissociation energy, or energy barrier for dissociation, is a unique value (i say this because the reaction 2H2O OH- + H3O+ follows, as far as I know, a series of steps, as has been described by ab initio calculations, see Saitta et al. Phys Rew. Lett 108, 207801 (2012)). In a dynamic system, an electric field introduces a sort of kinetic energy term for residual charges (either forming part of a dipole, or being indepent ions) that is eventually considered as a reduction of the barrier for dissociation. Truly, either water molecules or any other electrolyte dissociate more in the presence of an electric field. I am searching for a formula describing this dependence.
- Badges
- Science topic