EFFECTS OF COMPLEXING ON THE HOMOGENEOUS REDUCTION OF MERCURIC SALTS IN AQUEOUS SOLUTION BY MOLECULAR HYDROGEN

1956 ◽  
Vol 34 (10) ◽  
pp. 1372-1381 ◽  
Author(s):  
G. J. Korinek ◽  
J. Halpern
Keyword(s):  
Aqueous Solution ◽  
Molecular Hydrogen ◽  
Hydrogen Molecule ◽  
Bimolecular Reaction ◽  
Mercury Atom ◽  
Complexing Agents ◽  
Mercuric Ion ◽  
Rate Determining Step ◽  
Homogeneous Reduction

The effects of various complexing agents on the homogeneous reduction of mercuric salts by molecular hydrogen in aqueous solution were determined. In all cases the kinetics suggest that the rate-determining step is a bimolecular reaction between a mercuric ion or complex and a hydrogen molecule, probably leading to the formation of an intermediate mercury atom. The reactivity of various mercuric complexes was found to decrease in the following order: HgSO4 > Hg++ > HgAc2, HgPr2 > HgCl2 > HgBr2 > Hg(EDA)2++. Addition of anions such as OH−, CO3=, Ac−, Pr−, and Cl−, in excess of the amounts required to form stable mercuric complexes, was found to increase the rate. An interpretation of these effects is given.

scholarly journals The band spectrum of hydrogen

1924 ◽  
Vol 106 (735) ◽  
pp. 69-82 ◽  
Keyword(s):  
Molecular Hydrogen ◽  
Hydrogen Molecule ◽  
Spectral Lines ◽  
Wave Number ◽  
Band Spectrum ◽  
Wave Numbers ◽  
Experimental Side ◽  
The Subject ◽  
The Moment ◽  
Theoretical Side

Many attempts have been made to detect regularities amongst the numerous lines which constitute the secondary or many-lined spectrum of hydrogen. The extreme complexity of the spectrum may be realised from the fact that in the Bakerian Lecture of 1922 Merton and Barratt record some 750 lines in the interval between Hα (wave-number v = 5233.216) and Hβ ( v = 20564.793). Three methods of investigation may be employed in the search for regularities. (1) The lines may be classified according to their physical characteristics, such as intensity or mode of excitation, as in the tables of Merton and Barrat ( loc. cit .). (2) Lines may be grouped together by the discovery of relations between their wave-lengths or wave-numbers, as in the important groups of lines which have been arranged in bands by Fulcher. (3) Lastly, the question may be attacked from the theoretical side, and a model of the hydrogen molecule may be imagined, which will give rise to the emission of certain characteristic spectral lines. Thus Sutherland, working on the foundation of the classical mechanical laws, more than twenty years ago, came to the conclusion that spectral series must arise from kinematical considera­tions, and explained them by considering the nodal sub-divisions of a circle. At the present time we may expect more successful results to follow from the application of the quantum theory, and in this paper an endeavour will be made to examine the secondary spectrum of hydrogen, and more particularly the Fulcher bands, from this standpoint. I may add that my interest in the subject was aroused when attempting to construct a model of the hydrogen molecule, for it seemed that the most likely method of obtaining reliable information from the experimental side as to the moment of inertia of the molecule would be from a study of the spectrum of molecular hydrogen.

scholarly journals Spectroscopy of a rotating hydrogen molecule in carbon nanotubes

2019 ◽  
Vol 21 (7) ◽  
pp. 3423-3430 ◽  
Author(s):  
María Pilar de Lara-Castells ◽  
Alexander O. Mitrushchenkov
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Hydrogen ◽  
Hydrogen Molecule ◽  
Energy Levels

Computing the energy levels of molecular hydrogen rotating in carbon nanotubes of increasing size.

scholarly journals First-Principles Study of Molecular Adsorption of Hydrogen/s on Co-Adatom Graphene

2020 ◽  
Vol 25 (1) ◽  
pp. 15-23
Author(s):  
Nurapati Pantha ◽  
Saroj Thapa ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Binding Energy ◽  
First Principles ◽  
Molecular Hydrogen ◽  
Density Functional ◽  
Hydrogen Molecule ◽  
Cobalt Atom ◽  
Electronic Charge ◽  
Practical Applications ◽  
Electronic And Magnetic Properties

The study of graphene and its allotropes help to understand fundamental science and their role in the industry. The adsorption of transition metal adatom on mono-layer graphene can tune the geometrical, electronic, and magnetic properties of the material according to the requirement for the practical applications. In the present work, the geometrical stability, electronic and magnetic properties, and also the redistribution of electronic charge of single cobalt atom (Co) adsorbed graphene with reference to pure graphene have been investigated to develop a model system for the effective storage of hydrogen. The density functional theory (DFT) based first-principles calculations by incorporating van der Waals (VDW) interactions within DFT-D2 levels of approximation implemented in the quantum ESPRESSO package was used. The band structure and density of states of cobalt-adatom graphene show that the material is metallic and magnetic with a total magnetic moment of 1.55 μB. The change in the electronic distribution of Co-adatom graphene has been found favorable for adsorbing molecular hydrogen/s with greater strength. The increasing number of adsorbed molecular hydrogen/s (n=1 to 7) onto the substrate shows varying binding energy per hydrogen molecule, high enough at low concentration (n=1, 2, and 3), and then decreases slowly on increasing the value of n. The nature of adsorption and binding energy per hydrogen molecule (with a range of 0.116 - 0.731 eV/ H2) are found useful to meet a standard target for hydrogen storage in such materials.

CATALYTIC ACTIVATION OF HYDROGEN IN AQUEOUS SOLUTION BY THE CHLOROPALLADATE(II) ION

1959 ◽  
Vol 37 (9) ◽  
pp. 1446-1450 ◽  
Author(s):  
J. Halpern ◽  
J. F. Harrod ◽  
P. E. Potter
Keyword(s):  
Aqueous Solution ◽  
Ferric Chloride ◽  
Molecular Hydrogen ◽  
Homogeneous Catalyst ◽  
Rate Law ◽  
Catalytic Activation ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

The kinetics of the reduction of ferric chloride by molecular hydrogen in aqueous solution, in the presence of chloropalladate(II), were examined. The latter acts as a homogeneous catalyst for the reaction. The rate-law was found to be,[Formula: see text]where[Formula: see text]The mechanism of the reaction is discussed.

The kinetics of isomerization of allylbenzene homogeneously catalysed by palladium(II) in acetic acid

1973 ◽  
Vol 26 (12) ◽  
pp. 2635 ◽  
Author(s):  
BI Cruikshank ◽  
NR Davies
Keyword(s):  
Acetic Acid ◽  
Catalytic Activity ◽  
Experimental Evidence ◽  
Active Catalyst ◽  
Bimolecular Reaction ◽  
Equilibrium System ◽  
Constant Concentration ◽  
First Order ◽  
Rate Determining Step ◽  
Kinetics Of

The changes in the kinetics observed during the isomerization of allylbenzene catalysed by palladium(II) are interpreted in terms of the slow formation of a hydrido complex of palladium(II) which subsequently attains a constant concentration in an equilibrium system. The kinetics during these phases are shown to be consistent with first-order dependence on the concentration of an active catalyst formed in a bimolecular reaction from a mononuclear palladium(II) complex and with a regenerative hydrido-π-alkene-σ-alkyl mechanism of isomerization. The hypothesis that a further stage in the kinetics reflects a change in the rate determining step to one involving alkene displacement from the catalyst is supported by the experimental evidence. The concentration of active catalyst is shown not to fall appreciably until all the allylbenzene has undergone isomerization, but thereafter there is a slow reduction of catalytic activity which is not completely restored by the addition of further allylbenzene. It is suggested that the slow formation of a π-allylic complex is responsible.

scholarly journals A Selective Chemosensor for Mercuric Ions Based on 4-Aminothiophenol-Ruthenium(II) Bis(bipyridine) Complex

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Amer A. G. Al Abdel Hamid ◽  
Mohammad Al-Khateeb ◽  
Ziyad A. Tahat ◽  
Mahmoud Qudah ◽  
Safwan M. Obeidat ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Important Implication ◽  
Spectroscopic Techniques ◽  
Selective Detection ◽  
Conductivity Measurements ◽  
Mercuric Ion ◽  
Vis Spectroscopy ◽  
Mercuric Ions ◽  
Photochemical Properties ◽  
C Nmr

A new ruthenium(II) complex (cis-ruthenium-bis[2,2′-bipyridine]-bis[4-aminothiophenol]-bis[hexafluorophosphate]) has been synthesized and characterized using standard analytical and spectroscopic techniques, FTIR, 1H and 13C-NMR, UV/vis, elemental analysis, conductivity measurements, and potentiometric titration. Investigation of the synthesized complex with metal ions showed that this complex has photochemical properties that are selective and sensitive toward the presence of mercuric ion in aqueous solution. The detection limit for mercuric ions using UV/vis spectroscopy was estimated to be ~ 0.4 ppm. The results presented herein may have an important implication in the development of a spectroscopic selective detection for mercuric ions in aqueous solution.

The aniline catalysed decarboxylation of oxaloacetic acid

1965 ◽  
Vol 18 (3) ◽  
pp. 337 ◽  
Author(s):  
RW Hay
Keyword(s):  
Aqueous Solution ◽  
Transition State ◽  
Ethanol Solution ◽  
Keto Group ◽  
Fast Process ◽  
Schiff’S Base ◽  
Oxaloacetic Acid ◽  
Single Proton ◽  
Rate Determining Step ◽  
Rate Profile

Aniline catalysis of the decarboxylation of oxaloacetic acid, HO2CCOCH2CO2H + CH3COCO2H + CO2, has been studied in water and ethanol as solvent at 25�. In aqueous solution a maximum occurs in the pH-rate profile at pH 3.9, indicating the participation of a single proton in the transition state. Experiments with the half ester HO2CCOCH2CO2Et, which does not decarboxylate in the presence of amines, suggest that in aqueous solution the intermediate in the reaction is a carbinolamine formed between the amine and the keto group of the acid, and not a Schiff's base as has been previously suggested. In ethanol solution the intermediate is a Schiff's base, and formation of the Schiff's base is the rate-determining step, the actual decarboxylation being a fast process.

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