  The dependence of the actual/effective ionic concentration on the nominal
salt concentration is experimentally investigated for aqueous solutions of NaCl
and KCl. The actual ionic bulk density is determined by means of the impedance
spectroscopy technique using two approaches for the data analysis: A first
approach scrutinizing the real part's plateau of the cell's electric impedance
spectrum versus the bulk density of dopant when the impedance is written in the
series representation. A second one via extraction of the ionic density from
simultaneously fitting of the real and imaginary parts of the impedance
spectrum by using the Poisson-Nernst-Planck model. The validity of this
procedure reposes on the hypothesis that both the diffusion coefficient and the
dielectric constant are independent from the salt concentration in the explored
range of concentrations. Our experimental results indicate that a first-order
reaction describes well the dissociation phenomenon. The
dissociation-association ratio of the reaction has been calculated. Deviations
from linearity appear at rather low concentrations of the order of mM.
