Thermodynamic Quantities for the Ionization Reactions of Buffers

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238 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 6.99 66GOO/WIN 6.9 72GOO/IZA 6.74 30.0 76MCG/JOR 7.02 80POP/STE 6.85 87KIT/ITO 6.91 87POS/DEM 6.94 92GLA/HUL 6.847 30.43 62 97ROY/BIC 6.96 30.8 35 98FUK/TAK Comments: The most definitive results leading to the pK values are those of Roy et al. 97ROY/BIC who used an electrochemical cell with no liquid junction. We have adopted the respective averages of the reported rH° and rC p values. TABLE 7.2. Acetate Other names acetic acid; athylic acid; glacial acetic acid; vinegar; methanecarboxylic acid; ethanoic acid; CAS No. 64-19-7 Empirical formula C 2H 4O 2 Molecular weight 60.052 Ionization Reaction Evaluation: AAA Structure: CH 3COOHH CH 3COO Selected values at TÄ298.15 K and IÄ0: pK4.756, rG°/(kJ mol 1 )27.147, rH°/(kJ mol 1 )0.41, and rC p /(J K 1 mol 1 )142 Values from literature pK rH°/(kJ mol 1 ) T/K I Methods and comments Reference 0.80 298.15 0 The value of rH° given here is based on the calorimetric measurements by Richards and Mair 29RIC/MAI of the enthalpy of neutralization of acetic acid by NaOH. We have used their 29RIC/MAI value rH°/(kJ mol 1 )57.07 at T293.15 K and I0 together with rH° for the ionization of water at this temperature 75OLO/HEP to obtain rH°/(kJ mol 1 )0.09 for the ionization of acetic acid at T293.15 K. Use of the value rC p /(J K 1 mol 1 )142 leads to the value rH°/(kJ mol 1 ) 29RIC/MAI 4.756 298.15 0 0.80 for the ionization of acetic acid at T298.15 K. Conductivity. 32MAC/SHE 4.781 273.15 0 Electrochemical cell—no liquid junction. The value of rH° given here was calculated from pKs measured at several temperatures. The 1 1 value rC p/(J K mol )173 was also calculated from the temperature dependency of their 33HAR/EHL reported pKs. Inclusion of the term drC p/dT in these calculations did not substantively change the value of either rH° orrCp. The value of rH° given here differs from the value 0.41 kJ mol 1 4.770 278.15 0 33HAR/EHL 4.762 4.758 283.15 288.15 0 0 4.756 4.756 4.757 4.762 0.63 293.15 298.15 303.15 308.15 0 0 0 0 given by Harned and Owen 39HAR/OWE in their recalculation of the data 4.769 4.777 4.787 4.799 313.15 318.15 323.15 328.15 0 0 0 0 of Harned and Ehlers 33HAR/EHL. Interestingly, Harned and 1 1 Owen 39HAR/OWE also calculated rC p/(J K mol )173 in complete agreement with the value that we calculate from their data. 4.812 333.15 0 0.29 0 Calorimetry. 58CAN/PAP 3.02 298.15 3.0 M Calorimetry. 61SCH/MAR 0.75 298.15 0.2 M Calorimetry. 62WAD J. Phys. Chem. Ref. Data, Vol. 31, No. 2, 2002
IONIZATION REACTIONS OF BUFFERS Values from literature—Continued pK rH°/(kJ mol 1 ) T/K I Methods and comments Reference 4.763 298.15 0 Conductivity. 63ELL 4.799 323.15 0 4.957 373.15 0 5.204 423.15 0 5.509 473.15 0 5.757 498.15 0 0.38 298.15 0.1 M Calorimetry. 64NEL 0.38 298.15 0 Calorimetry. 66AVE 0.08 298.15 0 Calorimetry. 67CHR/IZA 0.38 298.15 0 Calorimetry. The value given here is based on our extrapolation to I0 of the unpublished results of Hansson that are given by Gerding 67GER. The value of rH° was found to be highly dependent on ionic strength and on the medium in which the ionization reaction was carried out. 67GER 3.36 273.15 0 Calorimetry. From the temperature dependence of rH°, one obtains the value rC p /(J K 1 mol 1 )147 for the ionization of acetic 70LEU/GRU acid at T298.15 K. 2.75 278.15 0 1.15 288.15 0 0.57 298.15 0 1.80 308.15 0 2.81 318.15 0 3.77 328.15 0 1.17 298.15 0.1 M Calorimetry. 72SIM/IVI 0.4 298.15 0.005 M Calorimetry. 74MOR/FAU 81ALL/WOO The value rC p /(J K 1 mol 1 )143 at T298.15 K was obtained from direct heat capacity measurements on acetic acid solutions. Values of rC p at T283.15 K and T313.15 K are also 3.19 0.41 3.86 273.65 298.15 323.15 0 0 0 reported. Calorimetry. From the temperature dependence of rH°, one obtains 1 1 the value rC p/(J K mol )143 for the ionization of acetic acid at T298.15 K. 11.02 373.15 0 The value rC p /(J K 1 mol 1 )143 at T298.15 K was obtained from direct heat capacity measurements on acetic acid 84OLO 84RIE/JOL 4.74 0.0 298.15 0 solutions. Potentiometric titration—glass electrode. The value of rH° given here was calculated from pKs measured at three temperatures. 85DAN/DER 4.780 273.15 0 Electrochemical cell with liquid junction. The pK values given here 89MES/PAT 4.757 0.51 298.15 0 are based on Mesmer et al.’s ‘‘Model I’’ see their Table V. The 4.786 4.848 4.937 323.15 348.15 373.15 0 0 0 value of rH° given here was calculated from pKs measured at 1 1 several temperatures. The value rC p/(J K mol )139 at T 298.15 K was also calculated from the temperature dependency of 5.047 398.15 0 their 89MES/PAT reported pKs. 5.180 423.15 0 5.334 448.15 0 5.515 473.15 0 5.727 498.15 0 5.978 523.15 0 6.282 548.15 0 6.664 573.15 0 0.316 0.436 1.104 293.15 298.15 303.15 0 0 0 Calorimetry. From the temperature dependence of rH°, one obtains 1 1 the value rC p/(J K mol )142 for the ionization of acetic acid at T298.15 K. 91HU/YEN 1.779 308.15 0 2.468 313.15 0 4.156 318.15 0 0.414 298.15 0 Calorimetry. 94LEI/ZON 98FUK/TAK 4.62 0.49 298.15 0.1 M Electrochemical cell with liquid junction; calorimetry. Fukada and Takahashi 98FUK/TAK also obtained rC p /(J K 1 mol 1 ) 128 at I0.1 M from the temperature dependence of rH° over the range 278.15–323.15 K. The value rC p /(J K 1 mol 1 )138 at T298.15 K and I0 was obtained from direct heat capacity measurements on acetic acid solutions. Values of rC p from T278.15 to T393.15 K are also reported. The pressure was 0.35 MPa. 239 99BAL/FOR 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: 7. Tables of Thermodynamic Quantiti
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 and 34: Values from literature—Continued
Page 45 and 46: TABLE 7.26. 3,3-Dimethylglutarate O
Page 47 and 48: TABLE 7.28. Ethanolamine Other name
Page 55 and 56: IONIZATION REACTIONS OF BUFFERS Val
Page 57 and 58: TABLE 7.33. Glycylglycine Other nam
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Values adjusted to TÄ298.15 K and
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IONIZATION REACTIONS OF BUFFERS Val
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Values from literature—Continued
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TABLE 7.38. HEPPSO Other names N-2-
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TABLE 7.42. Maleate Other names mal
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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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TABLE 7.51. Phosphate Other names p
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Values from literature pK rH°/(kJ
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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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