calculation from literature values with standard SSA and SSD at ionic strength of 1M, log K for pHzpc 8.4-8.6 in brackets for pHzpc 9-9.5 »Fe-OH2<1+> + ClO4<1-> = »Fe-OH2-ClO4 logK = 2.2(1.9) »Fe-OH + H<1+> = »Fe-OH2<1+> -pK1 = logK = 6.8 sum »Fe-OH + ClO4<1-> + H<1+> = »Fe-OH2-ClO4 logK = 2.2(1.9)+6.8 = 9.0(8.7)