scholarly journals ELECTROMETRIC DETERMINATIONS OF THE DISSOCIATION OF GLYCOCOLL AND SIMPLE PEPTIDES1

1930 ◽  
Vol 14 (2) ◽  
pp. 255-275 ◽  
Author(s):  
Philip H. Mitchell ◽  
Jesse P. Greenstein
Keyword(s):  
Ionic Strength ◽  
Dissociation Constants ◽  
Hydrogen Ion ◽  
Carboxyl Groups ◽  
Relative Order ◽  
Specific Ion Effects ◽  
Ion Activity ◽  
Order Of Magnitude ◽  
Ion Effects ◽  
Basic Dissociation

1. The apparent acid and basic dissociation constants were determined potentiometrically by the methods of hydrolysis and of titration for the following ampholytes: Glycocoll, glycylglycocoll, alanylglycocoll, valylglycocoll, leucylglycocoll, methylleucylglycocoll, phenylalanylglycocoll and glycylglycylglycocoll. The constants were also determined in the presence of KCl and of K2SO4 at equal ionic strength. 2. In general, the relative order of magnitude of the constants decreased as the number of carbon atoms between amino and carboxyl groups increased. An explanation of this is offered on the basis of theories of electronic structure. 3. The application of the modern concepts of solutions to the case of the ampholytic ions is discussed. The inadequacy of the present theories is pointed out. 4. The constants were found, in general, to be functions of the hydrogen ion activity and the ionic strength of the solutions. Apparent contradictions to the Debye-Hückel theory are pointed out and partially explained on the basis of specific ion effects.

Ionic Strength Correction for Extent of Ammonia Ionization in Freshwater

1984 ◽  
Vol 41 (5) ◽  
pp. 811-815 ◽  
Author(s):  
Jay J. Messer ◽  
Jimmy Ho ◽  
William J. Grenney
Keyword(s):  
Ionic Strength ◽  
Temperature Correction ◽  
Hydrogen Ion ◽  
Predictive Equation ◽  
Empirical Methods ◽  
Dissolved Solids ◽  
Ionization Fraction ◽  
Ion Activity ◽  
Thermodynamic Basis

Previously published tabulations of percent ammonia ionization inherently define pH in terms of concentration (molality) rather than the measured entity, hydrogen ion activity. In hard waters this may result in overestimation of the un-ionized NH3 concentration by 10–20%. The thermodynamic basis for current empirical methods for temperature correction is examined, and a tabulation of NH3 ionization fraction as a function of pH, temperature, and dissolved solids, together with a corresponding predictive equation, is presented.

THE ELECTRICAL CONDUCTIVITIES OF SOME TETRA-n-ALKYLAMMONIUM SALTS IN ACETONITRILE

1965 ◽  
Vol 43 (5) ◽  
pp. 1215-1221 ◽  
Author(s):  
A. C. Harkness ◽  
H. M. Daggett Jr.
Keyword(s):  
Dissociation Constants ◽  
Relative Order ◽  
Electrical Conductivities ◽  
Ionic Conductances ◽  
Order Of Magnitude ◽  
Alkylammonium Salts ◽  
Ion Size ◽  
Limiting Equivalent Conductances

The conductances of a number of tetra-n-alkylammonium bromides and iodides have been measured in acetonitrile. Limiting equivalent conductances and dissociation constants have been evaluated by two methods. Limiting equivalent ionic conductances have been evaluated from these results. Correlations have been made of the effect of ion size on the ionic conductances and on the relative order of magnitude of the dissociation constants. In an appendix the limiting ionic conductances of a number of other ions have been collected from the existing literature.

Ion effects in measurement of ionized calcium with a calcium-selective electrode.

1980 ◽  
Vol 26 (5) ◽  
pp. 640-644
Author(s):  
R A Kaufman ◽  
N W Tietz
Keyword(s):  
Ionic Strength ◽  
Osmotic Pressure ◽  
Calcium Ion ◽  
Important Variable ◽  
Ionized Calcium ◽  
Selective Electrode ◽  
Electrode Response ◽  
Ion Activity ◽  
Ion Effects ◽  
Significant Direct Effect

Abstract We examined the performance characteristics of an improved electrode for measurement of ionized calcium (Orion Research, Inc.) with respect to interferences by Na+, K+, Li+, Mg2+, and H+, as well as the effect of changes in ionic strength and osmolality. At physiologically observed concentrations, all ions except Na+ insignificantly affected ionized-calcium measurements. The decrease in ionized Ca2+ with increased Na+ concentration is caused by the increase in ionic strength and the associated decrease in Ca2+ activity. Sodium had no significant direct effect in concentrations below 250 mmol/L. A previously published (Clin. Chem. 23: 690, 1977) equation for the Na+ correction is invalid for this improved electrode. Changes in osmotic pressure negligibly affect electrode response. Significant changes in ionic strength, as would be observed in severe hypo- and hypernatremic sera, increase or decrease, respectively, values for ionized calcium by changing Ca2+ activity. With aqueous Ca2+ solutions, changes of less than or equal to 3% were observed for Na+ concentrations that deviate from 140 mmol/L by not more than 20 mmol/L. Because the calcium ion activity is considered to be the physiologically important variable, we suggest that no correlation be made for ionic strength effects.

Ion effects in measurement of ionized calcium with a calcium-selective electrode.

1980 ◽  
Vol 26 (5) ◽  
pp. 640-644 ◽  
Author(s):  
R A Kaufman ◽  
N W Tietz
Keyword(s):  
Ionic Strength ◽  
Osmotic Pressure ◽  
Calcium Ion ◽  
Important Variable ◽  
Ionized Calcium ◽  
Selective Electrode ◽  
Electrode Response ◽  
Ion Activity ◽  
Ion Effects ◽  
Significant Direct Effect

Abstract We examined the performance characteristics of an improved electrode for measurement of ionized calcium (Orion Research, Inc.) with respect to interferences by Na+, K+, Li+, Mg2+, and H+, as well as the effect of changes in ionic strength and osmolality. At physiologically observed concentrations, all ions except Na+ insignificantly affected ionized-calcium measurements. The decrease in ionized Ca2+ with increased Na+ concentration is caused by the increase in ionic strength and the associated decrease in Ca2+ activity. Sodium had no significant direct effect in concentrations below 250 mmol/L. A previously published (Clin. Chem. 23: 690, 1977) equation for the Na+ correction is invalid for this improved electrode. Changes in osmotic pressure negligibly affect electrode response. Significant changes in ionic strength, as would be observed in severe hypo- and hypernatremic sera, increase or decrease, respectively, values for ionized calcium by changing Ca2+ activity. With aqueous Ca2+ solutions, changes of less than or equal to 3% were observed for Na+ concentrations that deviate from 140 mmol/L by not more than 20 mmol/L. Because the calcium ion activity is considered to be the physiologically important variable, we suggest that no correlation be made for ionic strength effects.

Calculating pH in pig manure taking into account ionic strength

2008 ◽  
Vol 57 (11) ◽  
pp. 1785-1790 ◽  
Author(s):  
A. M. Nielsen ◽  
H. Spanjers ◽  
E. I. P. Volcke
Keyword(s):  
Anaerobic Digestion ◽  
Ionic Strength ◽  
Hydrogen Ion ◽  
Pig Manure ◽  
Hydrogen Ions ◽  
Charge Balance ◽  
Ph Measurements ◽  
Ph Values ◽  
Ion Activity ◽  
Ion Activities

Models such as the Anaerobic Digestion Model No. 1 (ADM1) assume that pH can be calculated directly from the concentration of hydrogen ions. However because pH is, by definition, the negative logarithm of the hydrogen ion activity, and thus pH measurements represent hydrogen ion activities, this approach may lead to a bias between measured and predicted pH values. Implementing ionic strength effects into the charge balance equation and the calculation of pH is a theoretical improvement to this. In this study a model, implementing a procedure for calculating pH, was developed to analyse the effect of ionic strength on pH in a pig manure. By adding KCl to samples of pig manure, experimental results could be analysed with help from the model. A modified form of the Davies equation was found to give the most accurate prediction of pH in the pig manure studied in this paper with changing ionic strength.

Determination of the second stoichiometric dissociation constants of glycine in aqueous sodium or potassium chloride solutions at 298.15 K

2003 ◽  
Vol 81 (12) ◽  
pp. 1462-1470 ◽  
Author(s):  
Jaakko I Partanen ◽  
Pekka M Juusola ◽  
Pentti O Minkkinen ◽  
Virginie Verraes
Keyword(s):  
Ionic Strength ◽  
Dissociation Constant ◽  
Dissociation Constants ◽  
Glass Electrode ◽  
Ionic Strength Dependence ◽  
Electrode Cell ◽  
Ion Activity ◽  
Strength Dependence ◽  
Single Ion Activity

Equations were determined for the calculation of the second stoichiometric (molality scale) dissociation constant, Km2, of glycine, in aqueous NaCl and KCl solutions at 298.15 K, from the thermodynamic dissociation constant, Ka2, of this acid and the ionic strength, Im, of the solution. The ionic strength of the solutions considered in this study is determined mostly by the salt alone, and the equations for Km2 were based on the single-ion activity coefficient equations of the Hückel type. New data measured by potentiometric titrations in a glass electrode cell were used in the estimation of the parameters for the Hückel equations of glycine species. By means of the calculation method suggested in this study, Km2 can be obtained almost within experimental error up to an Im of about 1.0 mol kg–1 for glycine in NaCl and KCl solutions. The Km2 values obtained by these methods were also compared with the values suggested in the literature for this quantity.Key words: ionic strength dependence, stoichiometric dissociation constant, Debye–Hückel equation, potentiometry, glycine.

Extraction of hafnium by means of some substituted 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-ones

1981 ◽  
Vol 46 (8) ◽  
pp. 1901-1905 ◽  
Author(s):  
Oldřich Navrátil ◽  
Jiří Smola
Keyword(s):  
Ionic Strength ◽  
Aqueous Phase ◽  
Dissociation Constants ◽  
Parent Substance ◽  
Benzoyl Group ◽  
Extraction Constants ◽  
Extraction Parameters ◽  
Substituted 1

Distribution between aqueous phase and benzene or chloroform was studied for 1-phenyl-3-methyl-4-benzoylpyrazol-5-ones with 2-chloro, 4-methoxy, 3-nitro, and 4-nitro substitution in the benzoyl group (ionic strength of the aqueous phase 0.1) and for hafnium in their presence (ionic strength 2.0). The distribution and dissociation constants of the reagents and the extraction constants of their hafnium complexes were determined. Hafnium was found to be extracted as the HfA4 species. The extraction parameters of the derivatives in question do not differ substantially from those of the parent substance.

Specific Ion Effects of Azobenzene Salts on Photoresponse of PNIPAm in Aqueous Solutions

2021 ◽  
pp. 2100232
Author(s):  
Shuang Wei ◽  
Zechuan Zhang ◽  
Weibin Dong ◽  
Ting Liang ◽  
Junyi Ji ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Specific Ion Effects ◽  
Ion Effects
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