The models in these systems, where a lone H4SiO4 interacts with its aqueous environment, are intended to represent silica in dilute concentrations. Hence, the results of the calculations suggest that, in dilute silica concentrations, the zwitterion is more likely to be observed as a stable species where salts are in low concentration while dipolar complex I is more likely to be observed in elevated salt concentrations. This can be interpreted to mean that the polarizing effect of NaCl perturbs the stability of OSAZ and stabilizes the auto-ionization product. (The preference is reversed in environments of higher concentrations of silica, and will be discussed in the next section.) It should be observed that the formation of OSAZ does not depend on pH (table ).