Mf. Camoes et al., CONSISTENCY OF PH STANDARD VALUES WITH THE CORRESPONDING THERMODYNAMIC ACID DISSOCIATION-CONSTANTS (TECHNICAL REPORT), Pure and applied chemistry, 69(6), 1997, pp. 1325-1333
With the simplest possible assumptions on the ion activity coefficient
s, namely a Debye-Huckel approach, pH values of eleven standard buffer
solutions have been calculated from the corresponding thermodynamic a
cidity constants, K(I-->0), and compared to the electrometrically assi
gned pH(S) values (by Hamed cell method). Agreement is within +/-0.01
in the temperature range 10-40 degrees C for all standards, except car
bonate. The results for the phthalate, acetate, phosphate and carbonat
e systems at 25 degrees C indicate that this consistency is improved i
f specific ion interactions are taken into account, according to the P
itzer theory.