The ionic product of water in highly concentrated aqueous electrolyte solutions

Kron, Ivan; Marshall, Stephanie Pace; May, Peter M.; Hefter, Glenn; Königsberger, Erich

doi:10.1007/bf00811002

Cited by 55 publications

(43 citation statements)

References 26 publications

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“…The former were determined by strong acid/strong base titrations in 1, 3 or 5 M (NaCl) as appropriate. The results obtained are summarized as pK w values in Table 1 and are in excellent agreement (≤±0.01) with previous determinations in the same media (Verhoeven et al, 1990;Kron et al, 1995). The cyanide protonation constants, as pK a (HCN), are also listed in Table 1 and agree to within about ± 0.01 with earlier measurements from our laboratory (Verhoeven et al, 1990) even at the highest ionic strength.…”

Section: Water Ionization and Protonation Constantssupporting

confidence: 84%

Investigation of complexation and solubility equilibria in the copper(I)/cyanide system at 25 °C

et al. 2016

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The complexation of copper(I) by cyanide ions (CN − ) in aqueous solution has been studied by glass electrode potentiometry at 25°C and ionic strengths (I) of 1, 3 and 5 M in NaCl media. Overall formation constants, β n , for the equilibria: Cu + (aq) + nCN − (aq) ⇌ Cu(CN) n (n−1)− (aq) with n = 2, 3 and 4, were quantified, along with the ionization constant (K w ) of water and the acid dissociation constant (K a ) of HCN(aq). The solubility constants *K sn for the equilibria: CuCN(s) + (n − 1)HCN 0 (aq) ⇌ Cu(CN) n (n −1)− (aq) + (n − 1)H + (aq) were also determined from a re-analysis of published solubility data for CuCN(s) in acidic cyanide solutions at I = 1 M(NaCl) and 25°C. Because of the instability of uncomplexed Cu + (aq) and parameter correlations in the data, neither β 1 nor the solubility product K s0 (CuCN(s) ⇌ Cu + (aq) + CN − (aq)) could be reliably determined from the present data although estimates are presented.

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Section: Water Ionization and Protonation Constantssupporting

confidence: 84%

Investigation of complexation and solubility equilibria in the copper(I)/cyanide system at 25 °C

et al. 2016

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“…In addition, the ionic strength was kept at 1.0 M for each NMR sample with KOH/KCl. This electrolyte pair was selected on the basis of having less self‐association, when compared with NaOH, and an overall higher p K w with the use of KOH . The titration was conveniently monitored from the chemical shift of the delta protons of arginine near 3.25 ppm [Fig.…”

Section: Resultsmentioning

confidence: 99%

“…NMR samples were prepared in 90%/10% H 2 O/D 2 O at varying calculated pH and constant ionic strength 1.0 M adjusted with KOH/KCl . Samples were prepared using KOH (with a constant ionic strength of 1.0 M using p K w = 14.16) and confirmed with a pH meter suitable for high pH measurements . Arginine concentrations for the 1 H NMR titrations were 0.5 and 50 m M for the 13 C natural abundance titrations.…”

Section: Methodsmentioning

confidence: 99%

Effect of methylation on the side-chain pK_avalue of arginine

et al. 2015

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Arginine methylation is important in biological systems. Recent studies link the deregulation of protein arginine methyltransferases with certain cancers. To assess the impact of methylation on interaction with other biomolecules, the pK a values of methylated arginine variants were determined using NMR data. The pK a values of monomethylated, symmetrically dimethylated, and asymmetrically dimethylated arginine are similar to the unmodified arginine (14.2 6 0.4). Although the pK a value has not been significantly affected by methylation, consequences of methylation include changes in charge distribution and steric effects, suggesting alternative mechanisms for recognition.

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“…An excellent (if by now a little old) coverage of the data available for this important equilibrium over a wide range of conditions is given in the book of Baes and Mesmer (1976). It is also worth noting some more recent data obtained under conditions of interest to the present study: glasselectrode potentiometric values, at high ionic strengths in various salt solutions (Kron et al, 1995), of the ionic product of water, pK w , = -log (…”

Section: Dissociation Constants For Water and Hydrogen Cyanidementioning

confidence: 99%

A critical review of the thermodynamics of hydrogen cyanide and copper(I)–cyanide complexes in aqueous solution

Kyle

Hefter

2015

Hydrometallurgy

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Kyle, J.H. and Hefter, G. (2015) A critical review of the thermodynamics of hydrogen cyanide and copper(I)-This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 AbstractDespite the importance of cyanide and of metal-cyanide complexes in gold hydrometallurgy, and the need for reliable thermodynamic data for modelling gold solution chemistry, no comprehensive critical overview of the thermodynamics of hydrogen/cyanide and metal/cyanide complex formation has appeared in the literature since that of Beck in 1987. In particular there has been little consideration of the values of the equilibrium constants (and related thermodynamic parameters) at the higher ionic strengths and non-standard temperatures more typical of hydrometallurgical processing. The copper(I)/cyanide system is of particular importance in gold hydrometallurgy as gold is often associated with copper sulfide minerals such as chalcopyrite, chalcocite, covellite and bornite, all of which except chalcopyrite are reasonably soluble in cyanide solutions due to the formation of copper(I)/cyanide complexes. This paper reviews the available thermodynamic data for the hydrogen/cyanide and copper(I)/cyanide systems in aqueous solution with special emphasis on measurements made at elevated ionic strengths and as a function of temperature. It has been found that, while reliable data are available at 25 o C and very low ionic strengths, the data for higher ionic strengths and temperatures are limited. An attempt has been made to rationalize the available data, and to point out areas where further careful measurements are desirable.

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The ionic product of water in highly concentrated aqueous electrolyte solutions

Cited by 55 publications

References 26 publications

Investigation of complexation and solubility equilibria in the copper(I)/cyanide system at 25 °C

Investigation of complexation and solubility equilibria in the copper(I)/cyanide system at 25 °C

Effect of methylation on the side-chain pK_avalue of arginine

A critical review of the thermodynamics of hydrogen cyanide and copper(I)–cyanide complexes in aqueous solution

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The ionic product of water in highly concentrated aqueous electrolyte solutions

Cited by 55 publications

References 26 publications

Investigation of complexation and solubility equilibria in the copper(I)/cyanide system at 25 °C

Investigation of complexation and solubility equilibria in the copper(I)/cyanide system at 25 °C

Effect of methylation on the side-chain pKavalue of arginine

A critical review of the thermodynamics of hydrogen cyanide and copper(I)–cyanide complexes in aqueous solution

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Effect of methylation on the side-chain pK_avalue of arginine