Thermodynamic Quantities for the Ionization Reactions of Buffers

242 GOLDBERG, KISHORE, AND LENNEN
Values from literature—Continued
pK rH°/(kJ mol 1 ) T/K I Methods and comments Reference
7.011 278.15 0 Electrochemical cell—no liquid junction. The value of rH° given
6.968 283.15 0
6.924 288.15 0
6.884 293.15 0
6.844 12.23 298.15 0
6.796 303.15 0
6.780 308.15 0
6.763 310.15 0
6.749 313.15 0
6.723 318.15 0
6.704 323.15 0
6.678 328.15 0
here was calculated from pKs measured at several temperatures. The
value rC p /(J K 1 mol 1 )144 was also calculated from the
temperature dependency of their 97ROY/GIB reported pKs.
81ROY/GIB
6.52 298.15 0.10 M Potentiometric titration—glass electrode. 96AHM/ELR
6.81 298.15 0.10 M Potentiometric titration—glass electrode. 96SHO/KHA
Values adjusted to TÄ298.15 K and IÄ0
pK rH°/(kJ mol 1 ) rC p /(J K 1 mol 1 ) Reference
Reaction „1…: H 3L ¿ ÄH 2L Á ¿H ¿
1.59 79NAK
Reaction „2…: H 2L Á ÄHL À ¿H ¿
2.51 55SCH/AND
2.52 79NAK
2.34 16.7 80BEN/BAL
2.56 96SHO/KHA
Reaction „3…: HL À ÄH ¿ ¿L 2À
7.03 55SCH/AND
6.99 66GOO/WIN
6.93 11.0 76MCG/JOR
7.10 79NAK
7.09 13.1 80BEN/BAL
6.844 12.23 144 81ROY/GIB
7.03 96AHM/ELR
7.23 96SHO/KHA
Comments: The average of the pK values has been adopted for reaction 2. For reaction 3, the results of Roy et al. 81ROY/GIB, which are based on an
electrochemical cell without liquid junction, have been judged to be the most accurate.
J. Phys. Chem. Ref. Data, Vol. 31, No. 2, 2002