Sulfate Protonation in Sodium Chloride and Sodium Perchlorate Media

Abstract

The equilibrium (association) constant, KA, for the first protonation of the sulfate ion in aqueous solution: [H+(aq) + {text{SO}}_{4}^{2 - }(aq) ⇌ {text{HSO}}_{4}^{ - }(aq)] has been measured at 298.15 K in NaCl and NaClO4 media using glass-electrode potentiometry at five ionic strengths in the range 0.5 ≤ I/(mol·dm−3) ≤ 5.0. The present KA values vary smoothly with I and are in good agreement with reliable literature data but indicate that the previously reported value of KA at I = 5 mol·dm−3 in NaClO4 media is in error.