Silicon-29 NMR studies of aqueous silicate solutions part 7: Exchange rates between anions

Silicon-29 NMR evidence is presented regarding the linewidths and the rates of chemical exchange between the smaller silicate anions in alkaline aqueous solutions of sodium and potassium silicates. It is found that the linewidths of different species vary, being relatively large for the dimer under most conditions. Moreover, as well as decreasing with increasing temperature, linewidths also appear to decrease with increasing pH. Some semi-quantitative values for lifetimes in particular solutions under given conditions are presented, but it is emphasized that these are minimum values, since there may be other origins for line-broadening.