The Stability Constants of Cadmium Chloride Complexes: Variation with Temperature and Ionic Strength<sup>1</sup>

Vanderzee, Cecil E.; Dawson, Harold J.

doi:10.1021/ja01118a056

Cited by 58 publications

(30 citation statements)

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“…This has been caused by different ionic strength of solutions, type of used supporting electrolyte, 20,29,30 its value is nearly 100 mol −1 ·dm 3 which is comparable with our results ( Table 3). The equilibrium constants, K(T), obtained in out work, are nearly linearly dependent on temperature …”

Section: ■ Results and Discussionsupporting

confidence: 95%

A Conductivity Study of Unsymmetrical 2:1 Type “Complex Ion” Electrolyte: Cadmium Chloride in Dilute Aqueous Solutions

2013

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Systematic and precise measurements of electrical conductivities of aqueous solutions of cadmium chloride were performed in the 2 × 10(-5)-1 × 10(-2) mol·dm(-3) concentration range, from 278.15 to 313.15 K. Determined conductances were interpreted in terms of molecular model which includes a mixture of two 1:1 and 2:1 electrolytes. The molar limiting conductances of λ(0)(CdCl(+), T) and λ(0)(1/2Cd(2+), T), the equilibrium constants of CdCl(+) formation K(T) and the corresponding standard thermodynamic functions were evaluated using the Quint-Viallard conductivity equations, the Debye-Hückel equations for activity coefficients and the mass-action equation. An excellent agreement between calculated and experimental conductivities was reached.

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Section: ■ Results and Discussionsupporting

confidence: 95%

A Conductivity Study of Unsymmetrical 2:1 Type “Complex Ion” Electrolyte: Cadmium Chloride in Dilute Aqueous Solutions

2013

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“…This value has been selected following prior usage of this value in the treatment of biochemical reactions 17,18 and earlier usage by Vasil'ev 19 and Vanderzee and Dawson. 20 Based upon the activity coefficient model, Eq. ͑13͒, the Debye-Hückel expressions for the excess enthalpy H i ex and heat capacity C i ex of species i are H i ex ϭRT 2 ͑ ‫ץ‬A m /‫ץ‬T ͒ p z i 2 I 1/2 /͑1ϩBI 1/2 ͒.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Quantities for the Ionization Reactions of Buffers

Goldberg¹,

Kishore²,

Lennen³

2002

Journal of Physical and Chemical Reference Data

584

481

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This review contains selected values of thermodynamic quantities for the aqueous ionization reactions of 64 buffers, many of which are used in biological research. Since the aim is to be able to predict values of the ionization constant at temperatures not too far from ambient, the thermodynamic quantities which are tabulated are the pK, standard molar Gibbs energy ⌬ r G ‫ؠ‬ , standard molar enthalpy ⌬ r H°, and standard molar heat capacity change ⌬ r C p ‫ؠ‬ for each of the ionization reactions at the temperature T ϭ298.15 K and the pressure pϭ0.1 MPa. The standard state is the hypothetical ideal solution of unit molality. The chemical name͑s͒ and CAS registry number, structure, empirical formula, and molecular weight are given for each buffer considered herein. The selection of the values of the thermodynamic quantities for each buffer is discussed. © 2002 by the U.S. Secretary of Commerce on behalf of the United States. All rights reserved.Of primary interest to this review is the ͑thermodynamic͒ equilibrium constant K a,m ϭa͕H ϩ ͑aq͖͒•a͕A Ϫ ͑aq͖͒/a͕HA͑aq͖͒ ͑1͒ for the ionization reaction HA͑aq͒ϭH ϩ ͑aq͒ϩA Ϫ ͑aq). ͑2͒The above equilibrium constant has been defined in terms of activity and has been denoted as such by affixing a subscript a to the equilibrium constant. It is also necessary to specify the standard state. In this review the principal standard state used for the solute is the hypothetical ideal solution at the standard molality (m°ϭ1 mol kg Ϫ1 ). The standard state for the solvent is the pure solvent. This choice of a molality standard state has been indicated by attaching a subscript m to the equilibrium constant. Eq. ͑1͒ can also be written in terms of the molalities and activity coefficients ͑molality ba-sis͒ ␥ m of the solute species:The standard molality m°has been used in Eq. ͑3͒ to keep the equilibrium constant dimensionless. An alternative way of writing Eq. ͑3͒ iswhere K m ϭm͕H ϩ ͑aq͖͒•m͕A Ϫ ͑aq͖͒/͓m͕HA͑aq͖͒•m°], ͑5͒andHere K m is the equilibrium constant ͑molality basis͒ that pertains to an actual real solution as distinct from the equilibrium constant ͑activity basis͒ that relates to a hypothetical standard state that is approached by real solutions as the sum of the molalities of all solute species approaches zero. One can also formulate equilibrium constants in terms of concentrations c:andHere, c°is the standard concentration ͑1 mol dm Ϫ3 ͒ and ␥ c is the activity coefficient on a concentration basis. The density of the pure solvent is needed to calculate values of K a,m from K a,c and vice versa:On a logarithmic scale the difference between K a,c and K a,m in water at Tϭ298.15 K is very small (pK a,c ϭpK a,m 236 236 GOLDBERG, KISHORE, AND LENNEN

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“…influence the linearity of the calibration curves. For example, the calibration curve for the aqueous solution of [2][3][4] ]) or 1 + K CuSO4 (*[SO [2][3][4] ])  constant holds actually. In other words, the condition indicates that the ion-pair formation is less effective for the b (slope) value of the calibration curve, while it is somewhat effective for the a (intercept) value.…”

Section: Log *[X] T -Dependence Of Emfmentioning

confidence: 99%

“…Many ion-pair (or complex) formation constants of divalent metal salts (MX 2 ) in water (w) have been determined so far [1][2][3][4]. In the course of potentiometric determination of these constants for CdI 2 and CdBr 2 in a bulk w by using a commercial Cd 2+ electrode with a solid-state membrane [4], plots of the emf versus log 2(*[CdX 2 ] t ) gave peaks, where *[CdX 2 ] t (= *[Cd] t ) denotes a total concentration of CdX 2 in the bulk w. Especially, as shown in Figure 1 of the previous paper [4], a slope of the plot for the CdI 2 system was positive in the lower range of log 2(*[CdI 2 ] t ), while it was negative in its higher range.…”

Section: Introductionmentioning

confidence: 99%

Elucidation of Abnormal Potential Responses of Cation-Selective Electrodes with Solid-State Membranes to Aqueous Solutions of CuCl2 and CdI2

Kudo¹,

Todoroki²,

Suzuki³

et al. 2011

AJAC

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An empirical solution to abnormal potential responses, showing peaks of emf, of commercial Cu2+- and Cd2+-selective electrodes with solid-state membranes was proposed for aqueous solutions of CuCl2 and CdI2. The two-step processes of Mn+ + Yn? (s: solid phase) MY(s) and MY(s) + 2X? X2MY2?(s) (n = 1, 2) at a test solution/electrode-interface were considered as a model. Here, Mn+, Yn?, and X? refer to a divalent or univalent cation, functional groups of electrode materials, and a halide ion (X? = Cl?, Br?, I?), respectively. By applying electrochemical potentials to these processes at n = 2, we derived an equation. Regression analyses based on the equation reproduced well the plots of emf versus log 2(*[M]t) for the Cd(II) and Cu(II) systems: *[M]t denotes a total concentration of species relevant to M2+ in a bulk of the aqueous solution. Also, we obtained log Ks(CdBr2) = 4.28 ? 0.22, log Ks(CdI2) = 6.98 ? 0.05, log Ks(CuCl2) = 3.96 ? 0.09, and log Ks(CuBr2) = 11.4 at 25?C. The magnitude in ?log Ks reflected that in the logarithmic solubility product, log {*[M2+](*[X?])2}, for bulk water, where *[M2+] or *[X?] denotes a molar concentration of the bulk solu-tion of M2+ or X? at equilibrium, respectively. Moreover, a mixture of CuSO4 with NaCl at the molar ratio of 1:1 yielded a plot similar to that of CuCl2

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The Stability Constants of Cadmium Chloride Complexes: Variation with Temperature and Ionic Strength¹

Cited by 58 publications

References 0 publications

A Conductivity Study of Unsymmetrical 2:1 Type “Complex Ion” Electrolyte: Cadmium Chloride in Dilute Aqueous Solutions

A Conductivity Study of Unsymmetrical 2:1 Type “Complex Ion” Electrolyte: Cadmium Chloride in Dilute Aqueous Solutions

Thermodynamic Quantities for the Ionization Reactions of Buffers

Elucidation of Abnormal Potential Responses of Cation-Selective Electrodes with Solid-State Membranes to Aqueous Solutions of CuCl2 and CdI2

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The Stability Constants of Cadmium Chloride Complexes: Variation with Temperature and Ionic Strength1

Cited by 58 publications

References 0 publications

A Conductivity Study of Unsymmetrical 2:1 Type “Complex Ion” Electrolyte: Cadmium Chloride in Dilute Aqueous Solutions

A Conductivity Study of Unsymmetrical 2:1 Type “Complex Ion” Electrolyte: Cadmium Chloride in Dilute Aqueous Solutions

Thermodynamic Quantities for the Ionization Reactions of Buffers

Elucidation of Abnormal Potential Responses of Cation-Selective Electrodes with Solid-State Membranes to Aqueous Solutions of CuCl2 and CdI2

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The Stability Constants of Cadmium Chloride Complexes: Variation with Temperature and Ionic Strength¹