Ionic strength dependence of formation constants.  Alkali metal complexes of ethylenediaminetetraacetate nitrilotriacetate, diphosphate, and tripolyphosphate in aqueous solution

Daniele, Pier Giuseppe; Rigano, Carmelo; Sammartano, Silvio

doi:10.1021/ac00291a046

Cited by 116 publications

(67 citation statements)

References 11 publications

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“…As expected, log ␤ H j values obtained in the two media are very different, as shown in Figure 1 (where log ␤ H 3 values of EGTA are plotted vs I g ), owing to the different ability of Na + and Et 4 N + to interact with complexons (Daniele et al, 1983(Daniele et al, , 1985.…”

Section: Resultssupporting

confidence: 62%

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Speciation of poly-amino carboxylic compounds in seawater

Crea

Stefano

Gianguzza

et al. 2003

Chemical Speciation & Bioavailability

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Section: Resultssupporting

confidence: 62%

“…www.scilet.com Values of log T ␤ j H of EGTA calculated by using eqn (1) are reported in Table 3 together with those of other complexons, such as NTA, EDTA (Daniele et al, 1985), DTPA and TTHA (De Stefano et al, 2003), already studied in these laboratories.…”

Section: Speciation Of Poly-amino Carboxylic Compounds In Seawater 78mentioning

confidence: 99%

Speciation of poly-amino carboxylic compounds in seawater

Crea

Stefano

Gianguzza

et al. 2003

Chemical Speciation & Bioavailability

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“…These results clearly indicate the ability of the calculations to take into account the variation of I obtained with KCl. As far as results obtained with a glass electrode are concerned, dependence on both I and the nature of the background electrolyte [26] is found, as expected. As for the comparison between primary and secondary apparatuses, it is clear that measurement conditions for both A and C type lead to better comparability, which is fundamental for dissemination purposes.…”

supporting

confidence: 84%

Role of the activity coefficient in the dissemination of pH: comparison of primary (Harned cell) and secondary (glass electrode) measurements on phosphate buffer considering activity and concentration scales

et al. 2005

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Role of the activity coefficient in the dissemination of pH: comparison of primary (Harned cell) and secondary (glass electrode) measurements on phosphate buffer considering activity and concentration scales Abstract Despite recent efforts devoted to assessing both the theoretical rationale and the experimental strategy for assignment of primary pH values, these have not yet been accomplished satisfactorily. Traceability and comparability of pH values are achieved only within the constraints of internationally accepted conventions and predefined conditions that cannot account for all possible situations when pH is measured. Critical parameters to be defined are, in particular, the activity coefficients (c i ) of the ionic species involved in the equilibrium with the hydrogen ions in the solution, which are usually estimated with the approximation typical of the Debye-Hu¨ckel theoretical model. For this paper, primary (Harned cell) measurements (traceable to the SI system) of the pH of a phosphate buffer have been considered and the results have been compared with secondary (glass electrode) measurements obtained by considering either the activity (paH) or concentration (pcH) scale of the hydrogen ions. With conventional approaches based on measurements related to activity or concentration scale, discrepancies emerge which have been assigned to incomplete inferences of c i arising from chemical features of the solution. It is shown that fitting and comparable paH and pcH results are attainable if evaluation of c i is performed using better estimates of the ionic strength, according to an enhanced application of the Debye-Hu¨ckel theory.

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“…[3]. Because our solutions contained relatively large amounts of "extra" electrolyte and also because the electrolytes are of different charge types, we have used two methods of carrying out these calculations.…”

Section: Results and Calculationsmentioning

confidence: 99%

“…It is also necessary to consider detailed speciation and contributions of "chemical relaxation" to the measured heat capacities. Calculations with the stability constants from Daniele et al (3) show that complexes of type M E D T A~-(~~ are the principal species, but concentrations of E D T A~-(~~ are too large to be ignored.…”

Section: 'mentioning

confidence: 99%

Thermodynamics of aqueous EDTA systems: Apparent and partial molar heat capacities and volumes of aqueous EDTA⁴⁻, HEDTA³⁻, H₂EDTA²⁻, NaEDTA³⁻, and KEDTA³⁻ at 25 °C. Relaxation effects in mixed aqueous electrolyte solutions and calculations of temperature dependent equilibrium constants

Hovey¹,

Hepler²,

Tremaine³

1988

Can. J. Chem.

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Calorimetric and densimetric measurements have led to apparent molar heat capacities and volumes for aqueous solutions of the mixed electrolytes [(CH3)4N]4EDTA + (CH3)4NOH, Na4EDTA + NaOH, and K4EDTA + KOH, and single electrolytes Na2H2EDTA and [(CH3)4N]3[HEDTA] at 25 °C. We have analyzed these results in terms of Young's rule and Pitzer's ion interaction model to obtain standard state partial molar heat capacities and volumes of EDTA4−(aq), HEDTA3−(aq), H2EDTA2−(aq), NaEDTA3−(aq), and KEDTA3−(aq) at 25 °C. For these calculations it was also necessary to evaluate the "relaxation" contribution to the measured heat capacities of some solutions. The partial molar heat capacities obtained here have been used with enthalpies from previous investigations for calculations of several equilibrium constants over wide ranges of temperature; volumes can be used for similar calculations of the effects of pressure.

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Ionic strength dependence of formation constants. Alkali metal complexes of ethylenediaminetetraacetate nitrilotriacetate, diphosphate, and tripolyphosphate in aqueous solution

Cited by 116 publications

References 11 publications

Speciation of poly-amino carboxylic compounds in seawater

Speciation of poly-amino carboxylic compounds in seawater

Role of the activity coefficient in the dissemination of pH: comparison of primary (Harned cell) and secondary (glass electrode) measurements on phosphate buffer considering activity and concentration scales

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Ionic strength dependence of formation constants. Alkali metal complexes of ethylenediaminetetraacetate nitrilotriacetate, diphosphate, and tripolyphosphate in aqueous solution

Cited by 116 publications

References 11 publications

Speciation of poly-amino carboxylic compounds in seawater

Speciation of poly-amino carboxylic compounds in seawater

Role of the activity coefficient in the dissemination of pH: comparison of primary (Harned cell) and secondary (glass electrode) measurements on phosphate buffer considering activity and concentration scales

Thermodynamics of aqueous EDTA systems: Apparent and partial molar heat capacities and volumes of aqueous EDTA4−, HEDTA3−, H2EDTA2−, NaEDTA3−, and KEDTA3− at 25 °C. Relaxation effects in mixed aqueous electrolyte solutions and calculations of temperature dependent equilibrium constants

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