calculation from literature values with standard SSA and SSD at ionic strength of 1M, log K for Aerosil in brackets for Cabosil content »Si-OH2<1+> + HS<1-> = »Si-OH2-HS logK = 6.5(6.1) »Si-OH + H<1+> = »Si-OH2<1+> - pK1 = logK = -1.4 sum »Si-OH + HS<1->+ H<1+> = »Si-OH2-HS logK=6.5(6.1)-1.4 = 5.1(4.7)