Thermodynamic Quantities for the Ionization Reactions of Buffers
Thermodynamic Quantities for the Ionization Reactions of Buffers
Thermodynamic Quantities for the Ionization Reactions of Buffers
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280 GOLDBERG, KISHORE, AND LENNEN<br />
TABLE 7.30. Glycerol 2-phosphate<br />
O<strong>the</strong>r names -glycerophosphate; 2-glycerophosphate; glycerol 2-monophosphate; glycerylphosphoric acid; CAS No. 17181-54-3<br />
Empirical <strong>for</strong>mula C 3H 9O 6P<br />
Molecular weight 172.07<br />
<strong>Ionization</strong> reaction<br />
H 2LH HL (1)<br />
HL H L 2 (2)<br />
where H 2LC 3H 9NO 6P<br />
Selected values at TÄ298.15 K and IÄ0:<br />
pK1.329, rG°/(kJ mol 1 7.586, rH°/(kJ mol 1 )12.2, and rC p /(J K 1 mol 1 )330 <strong>for</strong> reaction 1<br />
pK6.650, rG°/(kJ mol 1 )37.958, rH°/(kJ mol 1 )1.85, and rC p /(J K 1 mol 1 )212 <strong>for</strong> reaction 2<br />
Evaluation: reaction 1, ABB; reaction 2, AAA<br />
Structure:<br />
Values from literature<br />
pK rH°/(kJ mol 1 ) T/K I Methods and comments Reference<br />
Reaction „1…: H 2LÄH ¿ ¿HL À<br />
1.40 293.15 0.05 M Electrometric titration—hydrogen electrode. 26MEY/SUR<br />
1.36 291.15 0.06 M Potentiometric titration—glass electrode. 30MOR<br />
1.37 298.15 0.06 M Electrometric titration—hydrogen electrode. The temperature was<br />
ambient and is assumed to be 298.15 K.<br />
34KIE<br />
1.221<br />
1.252<br />
278.15<br />
283.15<br />
0<br />
0<br />
Electrochemical cell—no liquid junction. The value <strong>of</strong> rH° given<br />
here was calculated from pKs measured at several temperatures. The<br />
54ASH/CRO<br />
1.272<br />
1.296<br />
288.15<br />
293.15<br />
0<br />
0<br />
1 1 value rC p/(J K mol )330 was also calculated from <strong>the</strong><br />
temperature dependency <strong>of</strong> <strong>the</strong> reported 54ASH/CRO pKs.<br />
1.329 12.18 298.15 0<br />
1.373 303.15 0<br />
1.416 308.15 0<br />
1.460 313.15 0<br />
1.509 318.15 0<br />
1.549 323.15 0<br />
Reaction „2…: HLÀÄH ¿ ¿L2À 6.33 293.15 0.07 M Electrometric titration—hydrogen electrode. 26MEY/SUR<br />
6.67 0 303.15 0 Electrochemical cell with liquid junction—hydrogen and calomel<br />
electrodes. The results have been extrapolated to I0.<br />
28MOR<br />
6.32 291.15 0.09 M Potentiometric titration—glass electrode. 30MOR<br />
6.34 298.15 0.09 M Electrometric titration—hydrogen electrode. The temperature was<br />
ambient and is assumed to be 298.15 K.<br />
34KIE<br />
6.34 302.65 0.02 M Potentiometric titration—hydrogen and calomel electrodes. 39KIN/DEL<br />
6.657<br />
6.650<br />
278.15<br />
283.15<br />
0<br />
0<br />
Titrations were per<strong>for</strong>med at T295.15 K and at T310.15 K.<br />
Since only a mean value <strong>of</strong> <strong>the</strong> pK is reported, we have assigned a<br />
mean temperature <strong>of</strong> 302.65 K. The same result was again reported<br />
by Delory and King 43DEL/KIN.<br />
Electrochemical cell—no liquid junction. The value <strong>of</strong> rH° given<br />
here was calculated from pKs measured at several temperatures. The<br />
54ASH/CRO<br />
6.646<br />
6.647<br />
288.15<br />
293.15<br />
0<br />
0<br />
1 1 value rC p/(J K mol )228 was also calculated from <strong>the</strong><br />
temperature dependency <strong>of</strong> <strong>the</strong> reported 54ASH/CRO pKs.<br />
6.650 1.74 298.15 0<br />
6.655 303.15 0<br />
6.667 308.15 0<br />
6.678 313.15 0<br />
J. Phys. Chem. Ref. Data, Vol. 31, No. 2, 2002
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