ABSTRACT

We have measured the densities of aqueous solutions of glycine, glycine plus equimolal HCl, and glycine plus equimolal NaOH at temperatures 278.15 6 T/K 6 368.15, molalities 0.01 6 m/mol.kg-1 6 1.0, and at p = 0.35 MPa, using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15 6 T/K 6 393.15 and at the same m and p using a fixed-cell differential scanning calorimeter. We used the densities to calculate apparent molar volumes V/ and the heat capacities to calculate apparent molar heat capacities Cp,/ for these solutions. We used our results and values of V/(T,m) and Cp,/(T,m) for HCl(aq), NaOH(aq), NaCl(aq) from the literature to calculate parameters for DrCp,m(T,m) for the first and second proton dissociations from protonated aqueous cationic glycine. We then integrated this value of DrCp,m(T,m) in an iterative algorithm, using Young?s Rule to account for the effects of speciation and chemical relaxation on the observed V/ and Cp,/ of the solutions. This procedure yielded parameters for V/(T,m) and Cp,/(T,m) for glycinium chloride {H2Gly+Cl-(aq)} and sodium glycinate {Na+Gly-(aq)} which successfully modeled our observed results. We have then calculated values of rCp,m, DrHm, DrVm, and pQa for the first and second proton dissociations from protonated aqueous glycine as functions of T and m.

Compounds

#	Formula	Name
1	C2H5NO2	2-aminoacetic acid
2	H2O	water
3	ClH	hydrogen chloride
4	HNaO	sodium hydroxide

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	1 2	Apparent molar heat capacity, J/K/mol ; Liquid	Temperature, K; Liquid Molality, mol/kg - 1; Liquid	Pressure, kPa; Liquid	Liquid	Extra sensitive DSC	168
POMD	1 2	Apparent molar volume, m3/mol ; Liquid	Temperature, K; Liquid Molality, mol/kg - 1; Liquid	Pressure, kPa; Liquid	Liquid	Calculated with densities of this investigation	88
POMD	1 3 2	Apparent molar heat capacity, J/K/mol ; Liquid	Temperature, K; Liquid Molality, mol/kg - 1; Liquid Molality, mol/kg - 3; Liquid	Pressure, kPa; Liquid	Liquid	Extra sensitive DSC	216
POMD	1 3 2	Apparent molar volume, m3/mol ; Liquid	Temperature, K; Liquid Molality, mol/kg - 1; Liquid Molality, mol/kg - 3; Liquid	Pressure, kPa; Liquid	Liquid	Calculated with densities of this investigation	110
POMD	1 4 2	Apparent molar heat capacity, J/K/mol ; Liquid	Temperature, K; Liquid Molality, mol/kg - 1; Liquid Molality, mol/kg - 4; Liquid	Pressure, kPa; Liquid	Liquid	Extra sensitive DSC	168
POMD	1 4 2	Apparent molar volume, m3/mol ; Liquid	Temperature, K; Liquid Molality, mol/kg - 1; Liquid Molality, mol/kg - 4; Liquid	Pressure, kPa; Liquid	Liquid	Calculated with densities of this investigation	44

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Thermodynamics of proton dissociations from aqueous glycine at temperatures from 278.15 to 393.15 K, molalities from 0 to 1.0 mol.kg-1, and at the pressure 0.35 MPa: Apparent molar heat capacities and apparent molar volumes of glycine, glycinium chloride, and sodium glycinate

Ziemer, S. P.[S P], Niederhauser, T. L., Merkley, E. D., Price, J. L., Sorenson, E. C., McRae, B. R., Patterson, B. A., Origlia-Luster, M. L., Woolley, E. M.[Earl M.]

ABSTRACT