2017/09/10 by Sven Schlumpberger, Martin Z. Bazant, Schlumpberger, Sven +1
Chemical Engineering · Chemistry · Physics and Astronomy · #Chemical and Physical Properties in Aqueous Solutions #Inorganic and Organometallic Chemistry #Spectroscopy and Quantum Chemical Studies
paper · pdf · doi:10.48550/arxiv.1709.03106
The Debye-H" uckel formula for ionic activity coefficients is extended for concentrated solutions by solving a simple model of many-body Coulomb correlations and adding the Born solvation energy. Given the bulk permittivity, our formula is able to fit activity data for diverse electrolytes with only one parameter to adjust the correlation length, which interpolates between the Bjerrum length and the mean ion spacing. The results show that ionic activity in most electrolytes is dominated by three types of electrostatic forces: (i) mean-field charge screening, (ii) solvation, and (iii) Coulomb correlations, both "over-screening" (charge oscillations) and "under-screening" (extending beyond the Debye screening length).