Thermodynamic Quantities for the Ionization Reactions of Buffers

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264 GOLDBERG, KISHORE, AND LENNEN Values adjusted to TÄ298.15 K and IÄ0 pK rH°/(kJ mol 1 ) rC p /(J K 1 mol 1 ) Reference 9.86 97ORA/AZA 9.825 46.67 21 97ROY/MOO Comments: The results of Roy et al. 97ROY/MOO are based on an electrochemical cell without liquid junction and are judged to be the most reliable. TABLE 7.20. Carbonate Other names carbon dioxide; carbonic acid; bicarbonate; CAS No. 124-38-9 Note: CAS No. of carbonic acid is 463-79-6 Empirical formula CO 2 Molecular weight 44.01 Ionization reactions H 2CO 3H HCO 3 (1) HCO 3 H CO3 2 (2) Selected values at TÄ298.15 K and IÄ0: pK6.351, rG°/(kJ mol 1 )36.252, rH°/(kJ mol 1 )9.15, and rC p /(J K 1 mol 1 )371 for reaction 1 pK10.329, rG°/(kJ mol 1 )58.958, rH°/(kJ mol 1 )14.70, and rC p /(J K 1 mol 1 )249 for reaction 2 The values for pK, rG°, and rH° for this ionization reaction are based on the study and review of Berg and Vanderzee 78BER/VAN. The ‘‘CODATA Key Values for Thermodynamics’’ 89COX/WAG relies heavily on their 78BER/VAN results in the calculation of formation properties for the above species. Peiper and Pitzer 82PEI/PIT, in their review, selected the values pK 16.355 and pK 210.337. The differences between these and the Berg and Vanderzee 78BER/VAN values is probably within the experimental uncertainty in the pK values. The values for rC p are calculated from the standard molar heat capacities of CO 2aq), HCO 3 aq, and CO3 2 aq reported by Larson et al. 82LAR/ZEE and by Barbero et al. 83BAR/HEP. Alberty 95ALB, 97ALB has discussed the thermodynamic treatment of carbon dioxide solutions both in terms of the species present and in terms of total carbon dioxide as a reactant. Many additional studies, performed under a variety of conditions, are cited by Martell et al. 2001MAR/SMI and by Pettit and Powell 2000PET/POW. Evaluation: reaction 1, AAA; reaction 2, BAA Structure: TABLE 7.21. CHES Other names 2-cyclohexylaminoethanesulfonic acid; N-cyclohexyltaurine; 2-N-cyclohexylaminoethanesulfonic acid; CAS No. 103-47-9 Empirical formula C 8H 17NO 3S Molecular weight 207.29 Ionization reaction Evaluation: AAB Structure: J. Phys. Chem. Ref. Data, Vol. 31, No. 2, 2002 HL H L , where HLC 8H 17NO 3S Selected values at TÄ298.15 K and IÄ0: pK9.394, rG°/(kJ mol 1 )53.621, rH°/(kJ mol 1 )39.55, and rC p /(J K 1 mol 1 )9
Values from literature pK rH°/(kJ mol 1 ) T/K I Methods and comments Reference 9.38 298.15 0.012 M Potentiometric titration of sample 0.01–0.014 M with 0.1 M HCl or 0.1 M NaOH. 9.8897 278.15 0 Electrochemical cell—no liquid junction. Note that the value of rS° 9.7597 283.15 0 at T298.15 K given in Table 5 of Roy et al. 97ROY/BIC 9.6342 9.5132 288.15 293.15 0 0 contains a typographical error 2001ROY. The value of rH° given here was calculated from pKs measured at several temperatures. The 9.3944 9.2790 39.55 298.15 303.15 0 0 1 1 value rC p/(J K mol )9 was also calculated from temperature dependency of the reported 97ROY/BIC pKs. the 9.1687 308.15 0 9.1236 310.15 0 9.0603 313.15 0 8.9562 318.15 0 8.8551 323.15 0 8.7596 328.15 0 Values adjusted to TÄ298.15 K and IÄ0 87KIT/ITO 97ROY/BIC pK rH°/(kJ mol 1 ) rC p /(J K 1 mol 1 ) Reference 9.48 87KIT/ITO 9.394 39.55 9 97ROY/BIC Comments: The results of Roy et al. 97ROY/BIC have been selected as the most definitive. TABLE 7.22. Citrate Other names citric acid; 2-hydroxy-1,2,3-propanetricarboxylic acid; -hydroxytricarballylic acid; 2-hydroxytricarballylic acid; hydroxy- 1,2,3-propanetricarboxylic acid; hydroxytricarballylic acid; 2-hydroxypropane-1,2,3-tricarboxylic acid; CAS No. 77-92-9 Empirical formula C 6H 8O 7 Molecular weight 192.13 Ionization reactions H 3LH H 2L (1) H 2L H HL 2 (2) HL 2 H L 3 (3) where H 3LC 6H 8O 7 Selected values at TÄ298.15 K and IÄ0: pK3.128, rG°/(kJ mol 1 )17.855, rH°/(kJ mol 1 )4.07, and rC p /(J K 1 mol 1 )131 for reaction 1 pK4.761, rG°/(kJ mol 1 )27.176, rH°/(kJ mol 1 )2.23, and rC p /(J K 1 mol 1 )178 for reaction 2 pK6.396, rG°/(kJ mol 1 )36.509, rH°/(kJ mol 1 )3.38, and rC p /(J K 1 mol 1 )254 for reaction 3 Evaluation: reaction 1, AAB; reaction 2, AAB; reaction 3, AAB Structure: IONIZATION REACTIONS OF BUFFERS 265 J. Phys. Chem. Ref. Data, Vol. 31, No. 2, 2002
Page 1 and 2: Thermodynamic Quantities for the Io
Page 3 and 4: 2. Thermodynamic Background Of prim
Page 5 and 6: cal cells both with and without liq
Page 7 and 8: 7. Tables of Thermodynamic Quantiti
Page 9 and 10: IONIZATION REACTIONS OF BUFFERS Val
Page 11 and 12: TABLE 7.3. ADA Other names N-2-acet
Page 13 and 14: TABLE 7.4. 2-Amino-2-methyl-1,3-pro
Page 15 and 16: Values adjusted to TÄ298.15 K and
Page 19 and 20: Values from literature pK rH°/(kJ
Page 21 and 22: TABLE 7.10. Barbital Other names ba
Page 31 and 32: TABLE 7.17. Cacodylate Other names
Page 33: Values from literature—Continued
Page 37 and 38: Values from literature—Continued
Page 39 and 40: Values from literature pK rH°/(kJ
Page 45 and 46: TABLE 7.26. 3,3-Dimethylglutarate O
Page 47 and 48: TABLE 7.28. Ethanolamine Other name
Page 57 and 58: TABLE 7.33. Glycylglycine Other nam
Page 65 and 66: TABLE 7.38. HEPPSO Other names N-2-
Page 75 and 76: TABLE 7.42. Maleate Other names mal
Page 79 and 80: TABLE 7.44. MES Other names 2-N-mor
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TABLE 7.49. MOPSO Other names 3-N-m
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IONIZATION REACTIONS OF BUFFERS Val
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Values from literature—Continued
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TABLE 7.51. Phosphate Other names p
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Values from literature—Continued
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Values from literature pK rH°/(kJ
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Values adjusted to TÄ298.15 K and
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TABLE 7.55. POPSO Other names piper
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TABLE 7.60. TABS Other names N-tris
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TABLE 7.68. Tris Other names 2-amin
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IONIZATION REACTIONS OF BUFFERS 8.
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IONIZATION REACTIONS OF BUFFERS 27C
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IONIZATION REACTIONS OF BUFFERS 57N
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IONIZATION REACTIONS OF BUFFERS 68V
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IONIZATION REACTIONS OF BUFFERS 76W
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IONIZATION REACTIONS OF BUFFERS 90D
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Thermodynamic Quantities for the Ionization Reactions of Buffers

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