Open Journal of Physical Chemistry

Journal Information
ISSN / EISSN : 2162-1969 / 2162-1977
Current Publisher: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 161
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Latest articles in this journal

Hebah M. Abdel-Wahab, Joseph W. Bozzelli
Open Journal of Physical Chemistry, Volume 11, pp 13-53; doi:10.4236/ojpc.2021.112002

Abstract:
Structures and thermochemical properties of these species were determined by the gaussian M-062x/6-31 + G (D, P) calculation enthalpies of formation for 19 fluorinated ethanol and some radicals were calculated with a popular Ab initio and density functional theory methods: The gaussian M-062x/6-31 + G (D, P) via several series of isodesmic reactions. Entropies (S298° in Cal·Mol-1 K-1) were estimated using the M-062x/6-31 + G (D, P) computed frequencies and geometries. Contributions of entropy, S°298, and heat capacities, Cp(T) due to vibration, translation, and external rotation of the molecules were calculated based on the vibration frequencies and structures obtained from the M-062x/6-31 + G (D, P) Density Functional Method. Potential barriers are calculated using M-062x/6-31 + G (D, P) density functional method and are used to calculate rotor contributions to entropy and heat capacity using integration over energy levels of rotational potential. Rotational barriers were determined and hindered internal rotational contributions for s298° - 1500°, and cp (t) were calculated using the rigid rotor harmonic oscillator approximation, with direct integration over energy levels of the intramolecular rotation potential energy curves. Thermochemical properties of fluorinated alcohols are needed for understanding their stability and reactions in the environment and in thermal process.
Panagis G. Papadopoulos, Christopher G. Koutitas, Christos G. Karayannis, Panos D. Kiousis, Yannis N. Dimitropoulos
Open Journal of Physical Chemistry, Volume 11, pp 1-11; doi:10.4236/ojpc.2021.111001

Abstract:
A simple rational model is proposed for discharge of batteries with aqueous electrolytes, based on Nernst equation. Details of electrode kinetics are not taken into account. Only a few overall parameters of the battery are considered. A simple algorithm, with variable time step-length Δt, is presented, for proposed model. The model is first applied to Daniel cell, in order to clarify concepts and principles of battery operation. It is found that initial pinching, in time-history curve of voltage E-t, is due to initial under-concentration of product ion. Then, model is applied to a lead-acid battery. In absence of an ion product, and in order to construct nominator of Nernst ratio, such an ion, with coefficient tending to zero, is assumed, thus yielding unity in nominator. Time-history curves of voltage, for various values of internal resistance, are compared with corresponding published experimental curves. Temperature effect on voltage-time curve is examined. Proposed model can be extended to other types of batteries, which can be considered as having aqueous electrolytes, too.
Augustus Newton Ebelegi, Nimibofa Ayawei, Donbebe Wankasi
Open Journal of Physical Chemistry, Volume 10, pp 166-182; doi:10.4236/ojpc.2020.103010

Abstract:
A complete study of adsorption processes will be less complete if the structure and dynamics of its different elements and how they interact is not well captured. Therefore, the extensive study of adsorption thermodynamics in conjunction with adsorption kinetics is inevitable. Measurable thermodynamic properties such as temperature equilibrium constant and their non-measurable counterparts such as Gibbs free energy change, enthalpy, entropy etc. are very important design variables usually deployed for the evaluation and prediction of the mechanism of adsorption processes.
Khairia M. Al-Ahmary, Fatimah A. AlShehri, Faten M. Atlam, Mohamed K. Awad
Open Journal of Physical Chemistry, Volume 10, pp 1-32; doi:10.4236/ojpc.2020.101001

Abstract:
A charge transfer hydrogen bonded complex between the electron donor (proton acceptor) 2-amino-4,6-dimethylpyridine with the electron acceptor (proton donor) chloranilic acid has been synthesized and studied experimentally and theoretically. The stability constant recorded high values indicating the high stability of the formed complex. In chloroform, ethanol, methanol and acetonitrile were found the stoichiometric ratio 1:1. The solid complex was prepared and characterized by different spectroscopy techniques. FTIR, 1H and 13C NMR studies supported the presence of proton and charge transfers in the formed complex. Complemented with experimental results, molecular modelling using the density functional theory (DFT) calculations was carried out in the gas, chloroform and methanol phases where the existence of charge and hydrogen transfers. Finally, a good consistency between experimental and theoretical calculations was found confirming that the applied basis set is the suitable one for the system under investigation.
Robert A. Sizov
Open Journal of Physical Chemistry, Volume 10, pp 48-67; doi:10.4236/ojpc.2020.101003

Abstract:
The detection by the author of real magnetic charges, as well as true antielectrons in of atomic structures allowed him to establish that atomic shells, as well as shells of nucleons are electromagnetic, and not electronic. Namely electromagnetic shells are the sources of gravitational field which is the vortex electromagnetic field. The elementary source of gravitational field is the electromagnetic quasiparticle (S-Graviton) which consists of two coupled dipoles (the magnetic and electric) rotating in antiphase in the same atomic or nucleonic orbit. Electrons in atomic shells are rigidly embedded in the compositions of S-Gravitons and, as a rule, cannot individually participate, for example, in processes of interatomic chemical bonding. Depending on the vector conditions the gravitational fields can be both paragravitational (PGF) so and ferrogravitational (FGF). The overwhelming number of atomic shells and all shells nucleons emit PGF. Between the masses (bodies, atoms, nucleons, etc.) emitting of PGF is realized a force of gravitational “Dark energy” pressing masses to each other. It is the compression of masses by forces of the gravitational “Dark energy” that lies at basis Physics of chemical bond. Depending on implementation in atoms of the effects intra-atomic gravitational shielding/lensing (IAGS/L) discovered and investigated by the author, the gravitational interatomic bonding mechanisms are divided into two groups: non-covalent bonds (IAGS effect) and covalent bonds (IAGL effect). Within the framework of the gravitational bond mechanism of the latter group which is implemented with participation paragravitational orbitals, such chemical concept as valence acquires a real physical meaning. The replacing the erroneous electronic concept of chemical bonding by the gravitational concept implies replacing the notion “electronegativity” of element by the notion the “gravitational activity” while maintaining existing quantitative ability of atoms in molecules to attract atoms of other elements.
Panagis G. Papadopoulos, Christopher G. Koutitas, Panos D. Kiousis, Christos G. Karayannis, Yannis N. Dimitropoulos
Open Journal of Physical Chemistry, Volume 10, pp 99-116; doi:10.4236/ojpc.2020.102006

Abstract:
A simple algorithm is proposed for step-by-step time integration of stiff ODEs in Chemical Kinetics. No predictor-corrector technique is used within each step of the algorithm. It is assumed that species concentrations less than 10-6 mol·L-1 do not activate any chemical reaction. So, within each step, the time steplength Δt of the algorithm is determined from the fastest reaction rate maxR by the formula Δt = 10-6mol·L-1/max R. All the reversible elementary reactions occur simultaneously; however, by a simple book-keeping technique, the updating of species concentrations, within each step of the algorithm, is performed within each elementary reaction separately. The above proposed simple algorithm for Chemical Kinetics is applied to a simple model for hydrogen combustion with only five reversible elementary reactions (Initiation, Propagation, First and Second Branching, Termination by wall destruction) with six species (H2, O2, H, O, HO, H2O). These five reversible reactions are recommended in the literature as the most significant elementary reactions of hydrogen combustion [1] [2]. Based on the proposed here simple algorithm for Chemical Kinetics, applied to the global mechanism of proposed five reversible elementary reactions for hydrogen combustion, a simple and short computer program has been developed with only about 120 Fortran instructions. By this proposed program, the following are obtained: 1) The total species concentration of hydrogen combustion, starting from the sum of initial reactants concentrations [H2] + [O2], gradually diminishes, due to termination reaction by wall destruction, and tends to the final concentration of the product [H2O], that is to the 2/3 of its initial value, in accordance to the established overall stoichiometric reaction of hydrogen combustion 2H2 + O2 → 2H2O. 2) Time-histories for concentrations of main species H2, O2, H, H2O of hydrogen combustion, in explosion and equilibrium regions, obtained by the proposed program, are compared to corresponding ones obtained by accurate computational studies of [3]. 3) In the first step of the algorithm, the only nonzero species concentrations are those of reactants [H2], [O2]. So, the maximum reaction rate is that of the forward initiation reaction max R = Rif = kif[H2] [O2], where the rate constant kif is very slow. Thus, the first time steplength Δt1 = 10-6mol·L-1/max R results long in sec. After the first step, the sequences of all the following Δt’s are very short, in μsec. So, the first time steplength Δt1 can be considered as ignition delay time. 4) It is assumed that explosion corresponds to ignition delay time Δt1 t1 = 10 sec., can be considered as explosion limit curve. This curve is compared to the corresponding one obtained by the accurate computational studies of [2].
Paul Laffort
Open Journal of Physical Chemistry, Volume 10, pp 117-137; doi:10.4236/ojpc.2020.102007

Abstract:
An experimental characterization of the Van der Waals forces involved in volatile organic compounds (VOC) dissolved into stationary phases of gas liquid chromatography (GLC) has been started at the beginning of the seventies. This field has been reactivated from 1994 thanks to a fruitful cooperation between our CNRS team and the group of Ervin Kováts at the Federal Polytechnic School of Lausanne. The applied strategy can be summarized, in the first instance, as the experimental measurement of accurate and superabundant mutual affinities of a limited number of VOC and stationary phases and their processing using an original tool named Multiplicative Matrix Analysis (MMA). Then, in the second stage, the obtained results have been compared with molecular properties well established, as the Van der Waals molecular volume, the refraction index and the polar surface area (PSA), in order to get generalized values for any compound. The present study summarizes the positive results developed in our three last papers on this topic (2013, 2016 and 2018), as well as the attempt to overcome the negative ones using enthalpies of vaporization.
K. Elttaib, A. Benhmid
Open Journal of Physical Chemistry, Volume 10, pp 87-98; doi:10.4236/ojpc.2020.102005

Abstract:
The gravimetric analysis of electrodeposited nickel is demonstrated using electrochemical quartz crystal microbalance (EQCM) where the nickel coatings come from a solution of the metal chloride salt separately in either a1choline chloride: 2 ethylene glycol (ethaline) or 1 choline chloride: 2 urea (reline) based ionic liquid. The possibility of adapting the Quartz Crystal Microbalance EQCM (which measures the mass attached to the electrode) to probe kinetics of electrochemically-driven solid state phase transformations has been explored in a Ni electrodeposition in absence and presence of complexing agents ethylene diamine en and acetylacetonate acac from both electrolytes ethaline and reline. The study shows that the current efficiency and the rate of deposition of nickel coatings obtained from ethaline and reline baths in absence of brighteners en and acac are different, and the addition of en and acac to both ionic liquid solutions results in a significant decrease current. And the associated growth rate will also be decreased, suggesting that the en acac stops the formation and growth of Ni nuclei. This suggests that the mechanism of growth is changed.
André Tigori Mougo, Kouyaté Amadou, Kouakou Victorien, Marius Niamien Paulin, Trokourey Albert, Mougo André Tigori, Amadou Kouyaté, Victorien Kouakou, Paulin Marius Niamien, Albert Trokourey
Open Journal of Physical Chemistry, Volume 10, pp 139-157; doi:10.4236/ojpc.2020.103008

Abstract:
The theoretical study of chlorpropamide, tolazamide and glipizide was carried out by the Density Functional Theory (DFT) at B3LYP/6-31G(d) level. This study made it possible to determine the global reactivity parameters in order to better understand the interactions between the molecules studied and the copper surface. Then, the determination of local reactivity indices (Fukui functions and dual descriptor) on these molecules resulted in the precision on the most probable centers of nucleophilic and electrophilic attacks within each molecule. The results obtained, show that chloropropamide, tolazamide and glipizide can be good inhibitors against copper corrosion. Thus, the mechanism of copper corrosion inhibition of these compounds in nitric acid solution has been explained by means of theoretical calculations.
Mizukami Yoshihiro, Yoshihiro Mizukami
Open Journal of Physical Chemistry, Volume 10, pp 158-165; doi:10.4236/ojpc.2020.103009

Abstract:
We performed density functional theory (DFT) calculations for ribonucleotides and active triphosphate metabolites of candidate drugs against Coronavirus disease 2019 (Covid-19). Frontier orbitals (highest occupied molecular orbital and lowest unoccupied molecular orbital) at optimized structure of each molecule were obtained. T-705RTP (active triphosphate metabolite of favipiravir) and cytidine triphosphate (CTP) have similar shapes of frontier orbitals. We also obtained similar shapes of frontier orbitals among dihydroxy GS-441524 triphosphate (GS-441524 is an active triphosphate metabolite of remdesivir) and adenosine triphosphate (ATP). From a theoretical viewpoint, we suggest T-705RTP is a CTP analogue and dihydroxy GS-441524 triphosphate is an ATP analogue.
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