THE INTERPRETATION OF ELECTRICAL-CONDUCTIVITY MEASUREMENTS OF 3 MONOPROTONIC ACIDS IN FLUOROSULFURIC ACID

The three metal fluorosulfates Au(SO3F)5 and Ta(SO3F)5 are soluble in fluorosulfuric acid and behave as monoprotonic acids, as is evident from electrical conductivity measurements and conductometric titrations against the base KSO3F. Both the specific conductometric measurements in the concentration range of 0-0.050 mol-kg-1 and the conductometric titration curves are compared to calculated curves. Best fits are achieved by assuming an average degree of association for the Lewis acids of 5 for the Nb-, 3 for the Ta- and 2 for the Au-fluorosulfato species in HSO3F. Dissociation constants are calculated for various association models and a general order of acidity of Au(SO3F)3>Ta(SO3F)5>Nb(SO3F)5 is suggested, with association in solution occurring in the reverse order. © 1990 Plenum Publishing Corporation.