Mécanisme des réactions du chlorite et du dioxyde de chlore. 2. Cinétique des réactions du chlorite en présence d'ortho-tolidine

1984 ◽  
Vol 62 (11) ◽  
pp. 2231-2234 ◽  
Author(s):  
Guy Schmitz ◽  
Henri Rooze
Keyword(s):  
Ionic Strength ◽  
Chloride Ions ◽  
Elementary Reaction ◽  
Side Reactions ◽  
Rate Law ◽  
Intermediate Products

With added ortho-tolidine (NH2RNH2) in order to eliminate complicating side reactions of the intermediate products of the disproportionation of chlorite, the stoichiometry is HClO2 + 2NH2RNH2 → Cl− + H+ + 2NHRNH + 2H2O. No chlorate is formed. The rate law, in the absence of chloride ions, is[Formula: see text]k = 269 M−1 s−1 at 25 °C and 1 M ionic strength. Without added iron, the observed rate is only due to the small amount of iron always present as an impurity in the reactants. Thus the reaction [Formula: see text] is not an elementary reaction.

Kinetics and mechanism of oxidation of tris-(1,10-phenanthroline)iron(II) by chlorine and bromine and of the reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions

1979 ◽  
Vol 57 (15) ◽  
pp. 2065-2070 ◽  
Author(s):  
Jide Ige ◽  
J. Folorunso Ojo ◽  
Olusegun Olubuyide
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Activation Parameters ◽  
Chloride Ions ◽  
Reaction Intermediates ◽  
Rate Law ◽  
Iodide Ions ◽  
Good Linear ◽  
Linear Free Energy ◽  
Mechanism Of Oxidation

The rates of the oxidation of tris-(1,10-phenanthroline)iron(II) by chlorine and bromine, and of the reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions have been measured at ionic strength I = 1.0 mol dm−3 (LiClO4). All the reactions obey second-order rate law:[Formula: see text]The activation parameters for the reactions are: Fe(Phen)32+/Br2: ΔH≠ = (64.2 ± 3.2) kJ mol−1, ΔS≠ = −(24.9 ± 1.5) J mol−1 K−1. Fe(Phen)33+/I−:ΔH≠ = (39.8 ± 2.1) kJ mol−1, ΔS≠ = −(19.7 ± 0.8) J mol−1 K−1.The reactions of tris-(1,10-phenanthroline)iron(II) with chlorine and bromine are unaffected by chloride, bromide, and acid. The proposed mechanism for these reactions involves a series of one-electron changes, with the species X2− (X = Cl, Br) as reaction intermediates, since good linear free energy correlations for the primary step, resulting in the formation of X2−, are obtained. The reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions is catalysed by bromide and chloride ions, whereas the reduction of aquoiron(III) by iodide ions is known to be inhibited by bromide and chloride ions. A mechanistic interpretation of this observation is suggested.

Utilisation de l'ortho-tolidine pour l'étude des réactions des halogénates et halogénites

1986 ◽  
Vol 64 (9) ◽  
pp. 1747-1751 ◽  
Author(s):  
Guy Schmitz ◽  
Henri Rooze
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Fourth Order ◽  
Redox Reactions ◽  
Side Reactions ◽  
Acidity Constant ◽  
Acid Solutions ◽  
Complex Reaction ◽  
Rate Law ◽  
Bromic Acid

We have shown previously that ortho-tolidine greatly simplifies the kinetic study of redox reactions of chlorite by reacting with intermediate products and eliminating side reactions. The present study shows the validity of the method in the case of bromate reactions. For the bromate–bromide reaction it gives the classical fourth-order rate law with k = 1.54 M−3 s−1 in perchloric acid solutions at 25 °C and 1 M ionic strength, and an acidity constant of bromic acid of 2.9. This method is then used to study the reaction between bromate and chlorite, a complex reaction in the absence of ortho-tolidine. The rate law is[Formula: see text]with k = 0.83 + 0.76 [H+] in the same conditions. If [H+] = 0.1 M the apparent activation energy is 47.4 kJ/mol.

Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA

1994 ◽  
Vol 59 (6) ◽  
pp. 1311-1318 ◽  
Author(s):  
Ladislav Svoboda ◽  
Petr Vořechovský
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sodium Perchlorate ◽  
Exchange Capacity ◽  
Chloride Ions ◽  
Point Of View ◽  
Alkaline Media ◽  
Ion Exchangers ◽  
Acidic Media ◽  
Cadmium And Lead

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.

Effect of Chloride Ions on the Hydrolysis of Trivalent Lanthanum, Praseodymium and Lutetium in Aqueous Solutions of 2 M Ionic Strength

2005 ◽  
Vol 34 (4) ◽  
pp. 427-441 ◽  
Author(s):  
H. López-González ◽  
M. Solache-Ríos ◽  
M. Jiménez-Reyes ◽  
J. J. Ramírez-García ◽  
A. Rojas-Hernández
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Chloride Ions ◽  
Hydrolysis Of

OXYGEN EVOLUTION FROM SODIUM HYPOCHLORITE SOLUTIONS

1962 ◽  
Vol 40 (4) ◽  
pp. 729-733 ◽  
Author(s):  
M. W. Lister ◽  
R. C. Petterson
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Oxygen Evolution ◽  
Rate Constant ◽  
Sodium Hypochlorite ◽  
Chloride Ions ◽  
Effect Of Temperature

The rates of oxygen evolution from carefully purified solutions of sodium hypochlorite have been measured. Methods of purification are described, and it is found that substantially the same rate is observed regardless of the method of purification. The rate of oxygen evolution is proportional to the square of the concentration of hypochlorite ions. The effect of temperature and ionic strength are examined. The rate constant is 7.5 × 10−6 (g-mol/I.)−1(min)−1 at 60 °C and an ionic strength of 3.5; the activation energy is 26.6 kcal/g-mol. These results are compared with the corresponding quantities for the reaction of hypochlorite ions to form chlorite and chloride ions, and some tentative explanations are offered.

Substitution reactions on arsenic(V). The formation and hydrolysis of pentaamminearsenatocobalt(III) in aqueous solution

1973 ◽  
Vol 26 (9) ◽  
pp. 1877 ◽  
Author(s):  
TA Beech ◽  
NC Lawrence ◽  
SF Lincoln
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Bond Formation ◽  
The Other ◽  
Substitution Reactions ◽  
Rate Law ◽  
Hydrolysis Of ◽  
Hydrolysis Reactions

The formation of Co(NH3)5HAsO4+ and Co(NH3)5H2AsO42+ conforms to the rate law: ����������� rate = [Co(NH3)5H2O3+](k-1[HAsO42-]+k-2[H2AsO4-]) where k-1 = (11�1)x10-2 l. mol-1 s-1 and k-2 = (120�15)x10-4 l. mol-1 s-1 at 295 K and unit ionic strength. The hydrolysis of the arsenato complex conforms to the rate law: ������ rate = [total arsenato complex](Ka2k1+k2[H+]+k3[H+]2)(Ka2+[H+])-1 where k1 = (290�15)x10-7s-1, k2 = (408�20)x 10-6 s-1, k3 = (670�34)x10-3 l. mol-1 s-1, and pKa2 = 3.30�0.05 at 295 K and unit ionic strength. The formation and hydrolysis reactions proceed through bond formation and cleavage between oxygen and arsenic. The mechanisms of the reactions characterized by k1 and k-1 are considered to be associative substitutions on arsenic(v), but the mechanisms of the other reactions are less certain.

scholarly journals Self-Assembly of Charged Oligomeric Bilayers at the Aqueous/Organic Interface Regulated by Ion-Pair Associations

2020 ◽  
Author(s):  
Graham J. Taylor ◽  
Yingdong Luo ◽  
Kunlun Hong ◽  
Stephen A. Sarles ◽  
Robert L. Sacci ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Self Assembly ◽  
Soft Materials ◽  
Chloride Ions ◽  
Phospholipid Bilayer ◽  
Double Layers ◽  
Aqueous Interfaces ◽  
Device Applications ◽  
Disjoining Pressures ◽  
Assembly Behavior

<div> <p>Phospholipid bilayer membranes show promise as biomolecular soft materials that mimic the ability of living systems to sense, respond and learn but are fragile. Amphiphilic charged oligomers (oligodimethylsiloxane-methylimidazolium cation, ODMS-MIM<sup>(+)</sup>), assembled into bilayers at the oil-aqueous interfaces of droplet interface bilayers (DIBs), possessed similar size and functionality as phospholipid bilayers, but were stable. The ionic liquid headgroups (MIM<sup>(+)</sup>) of the oligomers were covalently bound to short-chain hydrophobic tails (ODMS). Bilayer self-assembly was influenced both by the charged headgroups, constrained to two-dimensional diffusion at the liquid-liquid interface, which formed electric double layers in the aqueous phase, and the tails in the organic phase. Bilayers formed spontaneously at low ionic strength but required an external voltage to form at higher ionicities. This switch in assembly behavior was due to ion-pairing of the MIM<sup>(+)</sup> headgroups with chloride ions, resulting in an increase in the density of the charged headgroups at the interface and the ODMS hydrophobic tails in the oil phase as they were covalently grafted to the headgroups. <a>Chain overlap led to repulsive disjoining pressures between droplets due to osmotic stress</a>. The applied voltage caused an attractive electrocompressive stress that overcame the repulsion, enabling bilayer formation. <a>Bilayer assembly at high ionic strength, while requiring a voltage to initiate, was irreversible, and the resulting membrane was considerably more stable than those formed at lower values of the ionic strength</a>. This switching of assembly behavior can be exploited as an additional mechanism for short-term synaptic plasticity in neuromorphic device applications using soft materials.</p> </div>

Electrogenesis in the Euryhaline Osmoconformer Cordylophora Lacustris (Hydrozoa)

1980 ◽  
Vol 88 (1) ◽  
pp. 175-194
Author(s):  
BENJAMIN M. CHAIN
Keyword(s):  
Ionic Strength ◽  
Action Potential ◽  
Natural Environment ◽  
Action Potentials ◽  
Typical Feature ◽  
Chloride Ions ◽  
Electrical Signals ◽  
Excitable System ◽  
Ionic Concentrations ◽  
Ionic Basis

The electrical signals propagated through the ectodermal epithelium of Cordylophora lacustris (the Josephson pulses) were recorded as transepithelial action potential-like events. Experiments on the ionic basis of electrogenesis of these action potentials suggested that they result from an outward flow of chloride ions from the ectodermal cells into the enteron. Further evidence for this hypothesis came from measurements of the ionic concentrations in the tissues of Cordylophora, which showed that these cells have unusually high levels of chloride. Chloride dependent electrogenesis allows this excitable system to function in media of low and variable ionic strength, which are a typical feature of this organism's natural environment.

Kinetics of Oxidation of Ferrocyanide by lodate Ion

1974 ◽  
Vol 52 (11) ◽  
pp. 2001-2004 ◽  
Author(s):  
Y. Sulfab ◽  
Hamid A. Elfaki
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Formation Constant ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
Ph Range ◽  
Kinetics Of ◽  
Rate Determining Steps

In the presence of vast excess of ferrocyanide, over the pH range 1.76–2.65, the reaction between iodate and ferrocyanide ions follows the rate law[Formula: see text]where ka and kb have values of 1.97 × 103 M−2 min−1 and 4.08 × 105 M−3 min−1, respectively, at an ionic strength of 1.18 M and a temperature of 25.0 ± 0.1 °C. K1 is the formation constant of monoprotonated ferrocyanide. The "overall activation energy" of the reaction was found to be 15.8 kcal/mol. Rate-determining steps consistent with the kinetics have been proposed.

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