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+> + Cl<1-> = »Fe-OH2-Cl logK = 2.8(2.0) »Fe-OH + H<1+> = »Fe-OH2<1+> -pK1 = logK = 6.8 sum »Fe-OH + Cl<1->+ H<1+> = »Fe-OH2-Cl logK= 2.8(2.0)+6.8 = 9.6(8.8)