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+> + F<1-> = »Fe-OH2-F logK = 5.1(4.0) »Fe-OH + H<1+> = »Fe-OH2<1+> -pK1 = logK = 6.8 sum »Fe-OH + F<1->+ H<1+> = »Fe-OH2-F logK= 5.1(4.0)+6.8 = 11.9(10.9)