Dissertations / Theses on the topic 'Thermochemistry'
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1
Yu, C. W. "Solution thermochemistry for rapid analysis." Thesis, University of Salford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381712.
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JUNIOR, AMERICO BARBOSA DA CUNHA. "REDUCTION OF COMPLEXITY IN COMBUSTION THERMOCHEMISTRY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=17685@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOO desenvolvimento de modelos computacionais para simulação de escoamentos reativos operando em regime de turbulencia requer a soluçao das equações diferenciais parciais que representam os balanços de massa, quantidade de movimento linear, espécies químicas e energia. Além disso, as reações químicas do modelo necessitam de um mecanismo cinético detalhado para descrição dos fenomenos físico-químicos associados. Um dos maiores desafios encontrados é a rigidez da simulação numérica desses modelos e a natureza não linear do termo de produção das espécies químicas. Esta dissertação apresenta uma revisão das principais técnicas disponíveis na literatura para o desenvolvimento de modelos reduzidos de cinética química, em particular para a combustão, bem como de técnicas para solução eficiente dos modelos de escoamentos reativos. Após uma apresentação da formulação matemática associada, a metodologia denominada tabulação adaptativa in situ (ISAT) é implementada e avaliada quanto a sua acurácia, eficiencia e uso de memória na simulação de alguns modelos de reator homogeneo agitado. Avalia-se a combustão de misturas de monóxido de carbono/oxigenio e metano/ar cujos mecanismos cinéticos tem 4 e 53 espécies, 3 and 325 reações respectivamente. Os resultados destassimulações indicam que a presente implementação da técnica ISAT tem erro relativo global inferior a 1%. Além disso, a técnica ISAT propiciou ganhos, em termos de tempo computacional, de at´e 80% quando comparado a simulação direta da cinética detalhada. Entretanto, em termos de utilização da memória, a implementação desenvolvida da técnica ISAT se mostrou excessivamente exigente.
The development of computational models for the numerical simulation of chemically reacting flows operating in the turbulent regime requires the solution of partial differential equations that represent the balance of mass, linear momentum, chemical species and energy. Moreover, the chemical reactions of the model may require a detailed reaction mechanism for the description of the physicochemical phenomena involved. One of the biggest challenges is the stiffness of the numerical simulation of these models and the nonlinear nature of species rate of reaction. This dissertation presents an overview of the main techniques available in the literature for the development of reduced models of chemical kinetics, particularly for the combustion, as well as the techniques for efficient computation of the chemically reacting flows models. After a presentation of the associated mathematical formulation, the methodology dubbed in situ adaptive tabulation (ISAT) is implemented and its accuracy, efficiency and memory usage are evaluated in the simulation of homogeneous stirred reactor models. The combustion of carbon monoxide with oxygen and methane with air mixtures is considered, which detailed reaction mechanisms involve 4 and 53 species, 3 and 325 reactions respectively. The results of these simulations indicate that the development implementation of the ISAT technique has a absolute global error of less than 1%. Moreover, the ISAT technique provided gains, in terms of computational time, of up to 80% when compared to the direct integration of the full chemical kinetics. However, in terms of memory usage the present implementation of ISAT technique was found to be excessively demanding.
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Misra, Ashutosh. "Kinetics and Thermochemistry of Halogenated Species." Thesis, University of North Texas, 1997. https://digital.library.unt.edu/ark:/67531/metadc278143/.
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Seakins, Paul W. "Thermochemistry and reaction kinetics of alkyl radicals." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276856.
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Tullo, Erica Jane. "Thermochemistry of Amino Acids and Constrained Diamines." W&M ScholarWorks, 2012. https://scholarworks.wm.edu/etd/1539623596.
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The gas-phase proton affinities of several highly basic amino acids and diamines were determined using the extended kinetic method in an ESI-quadrupole ion trap instrument. The non-protein amino acid L-canavanine is structurally related to L-arginine with an oxygen substituted for the terminal methylene group of L-arginine and is highly toxic to humans. The proton affinity of L-arginine, a protein amino acid, was determined to be 1036 kJ mol -1, whereas the proton affinity of L-canavanine was determined to be 1005 kJ mol-1. Thus, substitution of an oxyguanidino group for the guanidine group in L-arginine results in a large decrease in basicity. This decrease in basicity mirrors the solution behavior of these two amino acids in which the oxygen atom substitution causes a 5 pKa unit drop in basicity of L-canavanine relative to L-arginine. In addition, the proton affinities of the NPAAs L-canaline and L-citrulline were determined to be 952 kJ mol-1 and 990 kJ mol-1, respectively. The proton affinity values presented here for the NPAAs L-canavanine, L-canaline, and L-citrulline represent the first measurements for these compounds. Experiments were complemented by high-level hybrid density functional theory calculations. Theory values obtained for proton affinities were consistent with the theoretical findings except for L-arginine, which was higher than the experimentally determined value. This may be due to the small number of reference bases in the high basicity range used to determine the experimental value.;The proton affinities of the highly basic diamines cis-1,5-diaminocyclooctane, tetramethylcadaverine, and hexamethylcadaverine were determined to be 1002 kJ mol-1, 1013 kJ mol-1, and 1031 kJ mol-1, respectively. These values are consistent with the theory that diamines display increased basicity due to the stabilization that intramolecular hydrogen bonding provides.
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Shin, Seung Koo Beauchamp Jesse L. "Experimental and theoretical studies of silylenes, silicenium ions, and organometallic reactive intermediates." Diss., Pasadena, Calif. : California Institute of Technology, 1989. http://resolver.caltech.edu/CaltechTHESIS:11122009-115104264.
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Thesis (Ph. D.)--California Institute of Technology, 1989. UM #90-00,599.Advisor names found in the Acknowledgements pages of the thesis. Title from home page. Viewed 01/14/2010. Includes bibliographical references.
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Majdi, Hassan Shakir. "Investigation of the thermochemistry of some energetic compounds." Thesis, Royal Holloway, University of London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408003.
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Allott, Philip Hugh. "The thermochemistry of bromination of phenols and anilines." Thesis, Royal Holloway, University of London, 1986. http://repository.royalholloway.ac.uk/items/45ee4bfb-9be1-4500-9d03-2b883899c5cb/1/.
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A method has been developed for bromination of aromatic compounds in aqueous solution in an isoperibol calorimeter. The enthalpies of bromination of phenol to 2,4,6-tribromophenol and of aniline, 2-bromo-aniline, 4-bromoaniline and 2,4-dibromoaniline to 2,4,6-tribromo-aniline were measured using this method. These values were used to derive the standard enthalpies of formation of 2,4,6-tribromophenol, 2-bromoaniline, 4-bromoaniline, 2,4-dibromoaniline and 2,4,6-tribromo-aniline. The enthalpies of combustion of 2,4,6-tribromophenol and 2,4,6-tribromoaniline were measured using a rotating-bomb calorimeter. These values were used to derive the standard enthalpies of formation of 2,4,6-tribromophenol and 2,4,6-tribromoaniline. The discrepancy between these latter standard enthalpies of formation and those found using the solution calorimetric method is discussed, and possible sources of systematic error indicated. The solution calorimetric method was adapted for the thermometric titration of phenols in aqueous solution with an aqueous solution of bromine. The sequential nature of bromination of five compounds -phenol, 2-bromophenol, 2-methylphenol, 3-methylphenol and 2-hydroxy-benzoic acid - was investigated using this technique. The reasons for this sequentiality are discussed. abstract continued overleaf A complete data-processing system has been designed for the solution calorimeter. A microcomputer is used for data acquisition from the AC bridge of the calorimeter through an analogue-to-digital interface. The bridge voltage readings, once uploaded to a minicomputer, are processed to yield the corrected temperature change. Enthalpies of reaction can then be calculated and statistical analyses performed. The problems encountered in developing the system are discussed, especially with regard to the calculation of the corrected temperature change from the noisy temperature data. A least-squares cubic spline is used for curve-fitting and calculation of the first derivative of temperature versus time.
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Jorgensen, Kameron R. "Thermochemistry Investigations Via the Correlation Consistent Composite Approach." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc177216/.
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Since the development of the correlation consistent composite approach (ccCA) in 2006, ccCA has been shown to be applicable across the periodic table, producing, on average, energetic properties (e.g., ionization potentials, electron affinities, enthalpies of formation, bond dissociation energies) within 1 kcal/mol for main group compounds. This dissertation utilizes ccCA in the investigation of several chemical systems including nitrogen-containing compounds, sulfur-containing compounds, and carbon dioxide complexes. The prediction and calculation of energetic properties (e.g., enthalpies of formation and interaction energies) of the chemical systems investigated within this dissertation has led to suggestions of novel insensitive highly energetic nitrogen-containing compounds, defined reaction mechanisms for sulfur compounds allowing for increased accuracy compared to experimental enthalpies of formation, and a quantitative structure activity relationship for altering the affinity of CO2 with substituted amine compounds. Additionally, a study is presented on the convergence of correlation energy and optimal domain criteria for local Møller–Plesset theory (LMP2).
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Haworth, Naomi Louise. "Quantum Chemical Studies of Thermochemistry, Kinetics and Molecular Structure." Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/509.
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This thesis is concerned with a range of chemical problems which are amenable to theoretical investigation via the application of current methods of computational quantum chemistry. These problems include the calculation of accurate thermochemical data, the prediction of reaction kinetics, the study of molecular potential energy surfaces, and the investigation of molecular structures and binding. The heats of formation (from both atomisation energies and isodesmic schemes) of a set of approximately 120 C1 and C2 fluorocarbons and oxidised fluorocarbons (along with C3F6 and CF3CHFCF2) were calculated with the Gaussian-3 (G3) method (along with several approximations thereto). These molecules are of importance in the flame chemistry of 2-H-heptafluoropropane, which has been proposed as a potential fire retardant with which to replace chloro- and bromofluorocarbons (CFC�s and BFC�s). The calculation of the data reported here was carried out in parallel with the modelling studies of Hynes et al.1-3 of shock tube experiments on CF3CHFCF3 and on C3F6 with either hydrogen or oxygen atoms. G3 calculations were also employed in conjunction with the experimental work of Owens et al.4 to describe the pyrolysis of CFClBr2 (giving CFCl) at a radiation wavelength of 265 nm. The theoretical prediction of the dissociation energy of the two C-Br bonds was found to be consistent with the energy at which carbene production was first observed, thus supporting the hypothesis that the pyrolysis releases two bromine radicals (rather than a Br2 molecule). On the basis of this interpretation of the experiments, the heat of formation of CFClBr2 is predicted to be 184 � 5 kJ mol-1, in good agreement with the G3 value of 188 � 5 kJ mol-1. Accurate thermochemical data was computed for 18 small phosphorus containing molecules (P2, P4, PH, PH2, PH3, P2H2, P2H4, PO, PO2, PO3, P2O, P2O2, HPO, HPOH, H2POH, H3PO, HOPO and HOPO2), most of which are important in the reaction model introduced by Twarowski5 for the combustion of H2 and O2 in the presence of phosphine. Twarowski reported that the H + OH recombination reaction is catalysed by the combustion products of PH3 and proposed two catalytic cycles, involving PO2, HOPO and HOPO2, to explain this observation. Using our thermochemical data we computed the rate coefficients of the most important reactions in these cycles (using transition state and RRKM theories) and confirmed that at 2000K both cycles have comparable rates and are significantly faster than the uncatalysed H + OH recombination. The heats of formation used in this work on phosphorus compounds were calculated using the G2, G3, G3X and G3X2 methods along with the far more extensive CCSD(T)/CBS type scheme. The latter is based on the evaluation of coupled cluster energies using the correlation consistent triple-, quadruple- and pentuple-zeta basis sets and extrapolation to the complete basis set (CBS) limit along with core-valence correlation corrections (with counterpoise corrections for phosphorus atoms), scalar relativistic corrections and spin-orbit coupling effects. The CCSD(T)/CBS results are consistent with the available experimental data and therefore constitute a convenient set of benchmark values with which to compare the more approximate Gaussian-n results. The G2 and G3 methods were found to be of comparable accuracy, however both schemes consistently underestimated the benchmark atomisation energies. The performance of G3X is significantly better, having a mean absolute deviation (MAD) from the CBS results of 1.8 kcal mol-1, although the predicted atomisation energies are still consistently too low. G3X2 (including counterpoise corrections to the core-valence correlation energy for phosphorus) was found to give a slight improvement over G3X, resulting in a MAD of 1.5 kcal mol-1. Several molecules were also identified for which the approximations underlying the Gaussian-n methodologies appear to be unreliable; these include molecules with multiple or strained P-P bonds. The potential energy surface of the NNH + O system was investigated using density functional theory (B3LYP/6-31G(2df,p)) with the aim of determining the importance of this route in the production of NO in combustion reactions. In addition to the standard reaction channels, namely decomposition into NO + NH, N2 + OH and H + N2O via the ONNH intermediate, several new reaction pathways were also investigated. These include the direct abstraction of H by O and three product channels via the intermediate ONHN, giving N2 + OH, H + N2O and HNO + N. For each of the species corresponding to stationary points on the B3LYP surface, valence correlated CCSD(T) calculations were performed with the aug-cc-pVxZ (x = Q, 5) basis sets and the results extrapolated to the complete basis set limit. Core-valence correlation corrections, scalar relativistic corrections and spin orbit effects were also included in the resulting energetics and the subsequent calculation of thermochemical data. Heats of formation were also calculated using the G3X method. Variational transition state theory was used to determine the critical points for the barrierless reactions and the resulting B3LYP energetics were scaled to be compatible with the G3X and CCSD(T)/CBS values. As the results of modelling studies are critically dependent on the heat of formation of NNH, more extensive CCSD(T)/CBS calculations were performed for this molecule, predicting the heat of formation to be 60.6 � 0.5 kcal mol-1. Rate coefficients for the overall reaction processes were obtained by the application of multi-well RRKM theory. The thermochemical and kinetic results thus obtained were subsequently used in conjunction with the GRIMech 3.0 reaction data set in modelling studies of combustion systems, including methane / air and CO / H2 / air mixtures in completely stirred reactors. This study revealed that, contrary to common belief, the NNH + O channel is a relatively minor route for the production of NO. The structure of the inhibitor Nd-(N'-Sulfodiaminophosphinyl)-L-ornithine, PSOrn, and the nature of its binding to the OTCase enzyme was investigated using density functional (B3LYP) theory. The B3LYP/6-31G(d) calculations on the model compound, PSO, revealed that, while this molecule could be expected to exist in an amino form in the gas phase, on complexation in the active site of the enzyme it would be expected to lose two protons to form a dinegative imino tautomer. This species is shown to bind strongly to two H3CNHC(NH2)2+ moieties (model compounds for arginine residues), indicating that the strong binding observed between inhibitor and enzyme is partially due to electrostatic interactions as well as extensive hydrogen bonding (both model Arg+ residues form hydrogen bonds to two different sites on PSO). Population analysis and hydrogen bonding studies have revealed that the intramolecular bonding in this species consists of either single or semipolar bonds (that is, S and P are not hypervalent) and that terminal oxygens (which, being involved in semipolar bonds, carry negative charges) can be expected to form up to 4 hydrogen bonds with residues in the active site. In the course of this work several new G3 type methods were proposed, including G3MP4(SDQ) and G3[MP2(Full)], which are less expensive approximations to G3, and G3X2, which is an extension of G3X designed to incorporate additional electron correlation. As noted earlier, G3X2 shows a small improvement on G3X; G3MP4(SDQ) and G3[MP2(Full)], in turn, show good agreement with G3 results, with MAD�s of ~ 0.4 and ~ 0.5 kcal mol-1 respectively. 1. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 5967. 2. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 54. 3. R. G. Hynes, J. C. Mackie and A. R. Masri, Proc. Combust. Inst., 2000, 28, 1557. 4. N. L. Owens, Honours Thesis, School of Chemistry, University of Sydney, 2001. 5. A. Twarowski, Combustion and Flame, 1995, 102, 41.
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Haworth, Naomi Louise. "Quantum Chemical Studies of Thermochemistry, Kinetics and Molecular Structure." University of Sydney. Chemistry, 2003. http://hdl.handle.net/2123/509.
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This thesis is concerned with a range of chemical problems which are amenable to theoretical investigation via the application of current methods of computational quantum chemistry. These problems include the calculation of accurate thermochemical data, the prediction of reaction kinetics, the study of molecular potential energy surfaces, and the investigation of molecular structures and binding. The heats of formation (from both atomisation energies and isodesmic schemes) of a set of approximately 120 C1 and C2 fluorocarbons and oxidised fluorocarbons (along with C3F6 and CF3CHFCF2) were calculated with the Gaussian-3 (G3) method (along with several approximations thereto). These molecules are of importance in the flame chemistry of 2-H-heptafluoropropane, which has been proposed as a potential fire retardant with which to replace chloro- and bromofluorocarbons (CFC�s and BFC�s). The calculation of the data reported here was carried out in parallel with the modelling studies of Hynes et al.1-3 of shock tube experiments on CF3CHFCF3 and on C3F6 with either hydrogen or oxygen atoms. G3 calculations were also employed in conjunction with the experimental work of Owens et al.4 to describe the pyrolysis of CFClBr2 (giving CFCl) at a radiation wavelength of 265 nm. The theoretical prediction of the dissociation energy of the two C-Br bonds was found to be consistent with the energy at which carbene production was first observed, thus supporting the hypothesis that the pyrolysis releases two bromine radicals (rather than a Br2 molecule). On the basis of this interpretation of the experiments, the heat of formation of CFClBr2 is predicted to be 184 � 5 kJ mol-1, in good agreement with the G3 value of 188 � 5 kJ mol-1. Accurate thermochemical data was computed for 18 small phosphorus containing molecules (P2, P4, PH, PH2, PH3, P2H2, P2H4, PO, PO2, PO3, P2O, P2O2, HPO, HPOH, H2POH, H3PO, HOPO and HOPO2), most of which are important in the reaction model introduced by Twarowski5 for the combustion of H2 and O2 in the presence of phosphine. Twarowski reported that the H + OH recombination reaction is catalysed by the combustion products of PH3 and proposed two catalytic cycles, involving PO2, HOPO and HOPO2, to explain this observation. Using our thermochemical data we computed the rate coefficients of the most important reactions in these cycles (using transition state and RRKM theories) and confirmed that at 2000K both cycles have comparable rates and are significantly faster than the uncatalysed H + OH recombination. The heats of formation used in this work on phosphorus compounds were calculated using the G2, G3, G3X and G3X2 methods along with the far more extensive CCSD(T)/CBS type scheme. The latter is based on the evaluation of coupled cluster energies using the correlation consistent triple-, quadruple- and pentuple-zeta basis sets and extrapolation to the complete basis set (CBS) limit along with core-valence correlation corrections (with counterpoise corrections for phosphorus atoms), scalar relativistic corrections and spin-orbit coupling effects. The CCSD(T)/CBS results are consistent with the available experimental data and therefore constitute a convenient set of benchmark values with which to compare the more approximate Gaussian-n results. The G2 and G3 methods were found to be of comparable accuracy, however both schemes consistently underestimated the benchmark atomisation energies. The performance of G3X is significantly better, having a mean absolute deviation (MAD) from the CBS results of 1.8 kcal mol-1, although the predicted atomisation energies are still consistently too low. G3X2 (including counterpoise corrections to the core-valence correlation energy for phosphorus) was found to give a slight improvement over G3X, resulting in a MAD of 1.5 kcal mol-1. Several molecules were also identified for which the approximations underlying the Gaussian-n methodologies appear to be unreliable; these include molecules with multiple or strained P-P bonds. The potential energy surface of the NNH + O system was investigated using density functional theory (B3LYP/6-31G(2df,p)) with the aim of determining the importance of this route in the production of NO in combustion reactions. In addition to the standard reaction channels, namely decomposition into NO + NH, N2 + OH and H + N2O via the ONNH intermediate, several new reaction pathways were also investigated. These include the direct abstraction of H by O and three product channels via the intermediate ONHN, giving N2 + OH, H + N2O and HNO + N. For each of the species corresponding to stationary points on the B3LYP surface, valence correlated CCSD(T) calculations were performed with the aug-cc-pVxZ (x = Q, 5) basis sets and the results extrapolated to the complete basis set limit. Core-valence correlation corrections, scalar relativistic corrections and spin orbit effects were also included in the resulting energetics and the subsequent calculation of thermochemical data. Heats of formation were also calculated using the G3X method. Variational transition state theory was used to determine the critical points for the barrierless reactions and the resulting B3LYP energetics were scaled to be compatible with the G3X and CCSD(T)/CBS values. As the results of modelling studies are critically dependent on the heat of formation of NNH, more extensive CCSD(T)/CBS calculations were performed for this molecule, predicting the heat of formation to be 60.6 � 0.5 kcal mol-1. Rate coefficients for the overall reaction processes were obtained by the application of multi-well RRKM theory. The thermochemical and kinetic results thus obtained were subsequently used in conjunction with the GRIMech 3.0 reaction data set in modelling studies of combustion systems, including methane / air and CO / H2 / air mixtures in completely stirred reactors. This study revealed that, contrary to common belief, the NNH + O channel is a relatively minor route for the production of NO. The structure of the inhibitor Nd-(N'-Sulfodiaminophosphinyl)-L-ornithine, PSOrn, and the nature of its binding to the OTCase enzyme was investigated using density functional (B3LYP) theory. The B3LYP/6-31G(d) calculations on the model compound, PSO, revealed that, while this molecule could be expected to exist in an amino form in the gas phase, on complexation in the active site of the enzyme it would be expected to lose two protons to form a dinegative imino tautomer. This species is shown to bind strongly to two H3CNHC(NH2)2+ moieties (model compounds for arginine residues), indicating that the strong binding observed between inhibitor and enzyme is partially due to electrostatic interactions as well as extensive hydrogen bonding (both model Arg+ residues form hydrogen bonds to two different sites on PSO). Population analysis and hydrogen bonding studies have revealed that the intramolecular bonding in this species consists of either single or semipolar bonds (that is, S and P are not hypervalent) and that terminal oxygens (which, being involved in semipolar bonds, carry negative charges) can be expected to form up to 4 hydrogen bonds with residues in the active site. In the course of this work several new G3 type methods were proposed, including G3MP4(SDQ) and G3[MP2(Full)], which are less expensive approximations to G3, and G3X2, which is an extension of G3X designed to incorporate additional electron correlation. As noted earlier, G3X2 shows a small improvement on G3X; G3MP4(SDQ) and G3[MP2(Full)], in turn, show good agreement with G3 results, with MAD�s of ~ 0.4 and ~ 0.5 kcal mol-1 respectively. 1. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 5967. 2. R. G. Hynes, J. C. Mackie and A. R. Masri, J. Phys. Chem. A, 1999, 103, 54. 3. R. G. Hynes, J. C. Mackie and A. R. Masri, Proc. Combust. Inst., 2000, 28, 1557. 4. N. L. Owens, Honours Thesis, School of Chemistry, University of Sydney, 2001. 5. A. Twarowski, Combustion and Flame, 1995, 102, 41.
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Miller, Stuart Raymond. "Scandium-bearing open framework materials /." St Andrews, 2008. http://hdl.handle.net/10023/570.
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Magnus, Sandra Hall. "An Investigation of the relationship between the thermochemistry and emission behavior of thermionic cathodes based on the BaO-Sc₂O₃-WO₃ ternary system." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19625.
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Moy, Thomas M. "Synthesis and characterization of soluble, high temperature aromatic polyimides." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-10022007-144551/.
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Kapadia, Robin. "Syntheses, reactivity and thermochemistry of some organoplatinum and organopalladium complexes." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46379.
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Sadd, Peter Alan. "The effect of surfactants on heat and mass transfer to water drops in air." Thesis, University of Surrey, 1987. http://epubs.surrey.ac.uk/843252/.
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The temperatures and evaporation rates of surfactant-contaminated droplets were determined under controlled conditions. The surfactants used were sodium stearate, sodium palmitate, sodium myristate and sodium laurate. The drops were suspended on fine glass fibres or thermocouples in an environmental cell maintained at known temperature and humidity, and the evaporation rate was determined by optical measurement of the change of diameter with time. The results showed an early evaporation following a "clean" model, with a relatively sharp transition to a regime of "contaminated" evaporation kinetics. Simultaneous measurements of temperature and evaporation rate showed that the contaminants had no effect on heat transfer, i.e. their effect was limited to forming an additional mass transfer resistance. This mass transfer resistance increased strongly with initial surfactant concentration. Surfactants with longer carbon chains produced higher resistances, but after a longer delay. The partial differential equations describing surfactant diffusion within an evaporating drop were set up and solved, and an approximate analytical solution was shown to agree well with a numerical solution. By assuming that the surfactants retarded evaporation at the drop surface both by presenting a diffusional resistance to water transport and by vapour pressure lowering, a model was constructed to predict the evaporation behaviour of contaminated drops. It predicted the results obtained with sodium stearate well, but was unable to explain the results for shorter chain surfactants which were complicated by their adsorption behaviour at the surfactant-water interface. This model of single drop evaporation was extended to describe the evaporation of contaminated aerosols and used in an attempt to explain the measurements of Raper et al. (1982). Their results could not be explained quantitatively by a surfactant contaminant (though a surfactant would have produced similar qualitative features) and were probably caused by experimental error.
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Suitch, Paul Raymond. "Thermochemical reactions in tungsten-matrix dispenser cathods impregnated with various barium-calcium-aluminates." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/9502.
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Peebles, Lynda Renee. "Investigations of Thermochemistry and the Kinetics of H Atom Radical Reactions." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3275/.
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The thermochemistry of several species, and the kinetics of various H atom radical reactions relevant to atmospheric and combustion chemistry were investigated using ab initio theoretical techniques and the flash photolysis / resonance fluorescence technique. Using ab initio quantum mechanical calculations up to the G3 level of theory, the C-H bond strengths of several alkanes were calculated. The bond strengths were calculated using two working reactions. From the results, it is apparent that the bond strengths decrease as methyl groups are added to the central carbon. The results are in good agreement with recent experimental halogenation kinetic studies. Hydrogen bond strengths with sulfur and oxygen were studied via CCSD(T) theory, together with extrapolation to the complete basis set limit. The results for the bond dissociation energies (ground state at 0 K, units: kJ mol-1) are: S-H = 349.9, S-D = 354.7, HS-H = 376.2, DS-D = 383.4, and HO-H = 492.6. These data compare well with experimental literature. The rate constants for the isotopic reactions of H + H2S, D + H2S, H + D2S, and D + D2S are studied at the QCISD(T)/6-311+G(3df,2p) level of theory. The contributions of the exchange reaction versus abstraction are examined through transition state theory. The energy of NS was computed via CCSD(T) theory, together with extrapolation to the complete basis set limit. The results were employed with three working reactions to find ΔfH0(NS) = 277.3 ± 2 kJ mol-1 and ΔfH298(NS) = 278.0 ± 2 kJ mol-1. This thermochemistry is consistent with, but much more precise than, earlier literature values. A kinetic study of the reaction of H + CH2CCl2 was conducted over the temperature range of 298 - 680 K. The reaction was found to be pressure dependent and results of the rate constants and their interpretation via unimolecular rate theory are presented.
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Borkar, Sampada N. "Very accurate gas-phase thermochemistry through photoelectron photoion coincidence (PEPICO) spectroscopy." Scholarly Commons, 2013. https://scholarlycommons.pacific.edu/uop_etds/144.
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Five projects are presented here that use Photoelectron Photoion Coincidence (PEPICO) Spectroscopy to determine high-accuracy thermochemical data on small and intermediate size molecules and radicals that are relevant in modeling combustion and atmospheric processes. Some of the experiments were carried out on the laboratory-based Threshold PEPICO (TPEPICO) apparatus which has the advantage of having a low-temperature inlet system and unlimited measurement time, while most of the projects involved the use of the Imaging PEPICO (iPEPICO) apparatus at the Swiss Light Source, which is capable to determine ionic dissociation energies to sub-kJ/mol accuracy. The iPEPICO on the synchrotron beamline was also useful where measurements required energies in excess of 14 eV. The modeling framework of PEPICO is based on the RRKM statistical theory of dissociation kinetics and statistical energy distributions and models complex dissociation pathways to extract both kinetics and thermochemical data from the experiment. In the first project, we measured the onsets of Br- and I-loss reactions for C 2 H 5 Br and C 2 H 5 I using TPEPICO, respectively. The heats of formations of the two molecules are related through the ethyl cation, which was used in their determination. The second project involved measuring Cl-loss from four S i O j Cl k compounds viz. SCl 2 , S 2 Cl 2 , SOCl 2 , and SO 2 Cl 2 to obtain reliable thermochemistry. The second Cl-loss from S 2 Cl 2 + and SOCl 2 + helped us conclude that assuming three-dimensional translational degrees of freedom yields a more reliable statistical model of product-energy distributions. The third project investigated methanol and its isotopologues to explore the dissociation pathways through the H/D-losses. The 0 K appearance energies were used to determine the accurate heat of formation of CH 2 OH and the proton affinity of formaldehyde. The fourth project explores the dissociation pathways of cis -1-bromopropene, trans -1-bromopropene, 2-bromopropene, 3-bromopropene and bromocyclopropane to find that except for 2-bromopropene, all other isomers dissociate into the allyl cation. To derive accurate thermochemical information on the neutral precursors, a mixed theoretical and experimental thermochemical network was used to determine their 0 K heats of formation. The last project involves measurements on dimethyl disulfide (DMDS) and dimethyl diselenide, which are the simplest models that can be used to study disulfide and diselenide linkages. There are several discrepancies in the thermochemistry of DMDS, whereas ours is the first experimental attempt to study the ionic thermochemistry of dimethyl diselenide experimentally.
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Peng, Jianqiang. "Thermochemistry and constitution of precursor derived Si-(B-)C-N ceramics." [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10069814.
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Sebbar, Nadia. "Thermochemistry and kinetics for the oxidative degradation of dibenzofuran and precursors." Karlsruhe : Universitätsverlag, 2006. http://www.uvka.de/univerlag/volltexte/2006/185/.
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Guiver, S. C. "Thermochemistry of cyclic and acyclic radicals and kinetics of their recombination reactions." Thesis, Open University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376044.
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Telotte, John Charles. "Thermodynamic properties of multicomponent mixtures from the solution of groups approach to direct correlation function solution theory." Gainesville, FL, 1985. http://www.archive.org/details/thermodynamicpro00telo.
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Shepler, Benjamin C. "Ab initio investigation of the thermochemistry, spectroscopy and dynamics of reactions between mercury and reactive halogen species." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/summer2006/b%5Fshepler%5F072806.pdf.
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Ferrell, Virginia M. "Experimental studies of the kinetics and thermochemistry of the reactions Br + C₂H₄<->C₂H₄Br and Br + C₂H₆<->C₂H₅ + HBr." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/30002.
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Chippindale, A. M. "Studies of some insertion compounds." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382719.
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Ferger, Neil Michael. "Some gas phase reactions of oxygen and halogen atoms under single collision conditions." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257953.
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Jamea, E. H. "The thermochemistry of some organic compounds of germanium and associated vapour pressure studies on these and other organo-metallic compounds." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382905.
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Liu, Ting-Yueh. "Effects of natural and forced convection on thermal explosions." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610835.
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Welch, Mark David. "Experimental studies of selected amphiboles in the system Na2O-CaO-MgO-Al2O3-SiO2-H2O-F2 and its subsystems." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/11947.
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LUPI, Jacopo. "Computational strategies for the accurate thermochemistry and kinetics of gas-phase reactions." Doctoral thesis, Scuola Normale Superiore, 2022. https://hdl.handle.net/11384/125743.
Full textAbstract:
This PhD thesis focuses on the theoretical and computational modeling of gas phase
chemical reactions, with a particular emphasis on astrophysical and atmospherical
ones. The ability to accurately determine the rate coefficients of key elementary reactions
is deeply connected to the accurate determination of geometrical parameters,
vibrational frequencies and, even more importantly, electronic energies and zeropoint
energy corrections of reactants, transition states, intermediates and products
involved in the chemical reaction, together with a suitable choice of the statistical
approach for the rate computation (i.e. the proper transition state theory model).
The main factor limiting the accuracy of this process is the computational time
requested to reach meaningful results (i.e. reaching subchemical accuracy below
1 kJ mol−1), which increases dramatically with the the size of the system under investigation.
For small-sized systems, several nonempirical procedures have been developed
and presented in the literature. However, for larger systems the well-known
model chemistries are far from being parameter-free since they include some empirical
parameters and employ geometries which are not fully reliable for transition
states and noncovalent complexes possibly ruling the entrance channels. Based on
these premises, this dissertation has been focused on the development of new “cheap”
composite schemes, entirely based on the frozen core coupled cluster ansatz including
single, double, and (perturbative) triple excitation calculations in conjunction with
a triple-zeta quality basis set, including the contributions due to the extrapolation
to the complete basis set limit and core-valence effects using second-order Møller-
Plesset perturbation theory. For the first time the “cheap” scheme has been extended
to explicitly-correlated methods, which have an improved performance with respect
to their conventional counterparts. Benchmarks with different sets of state of the
art energy barriers, interaction energies and geometrical parameters spanning a wide
range of values show that, in the absence of strong multireference contributions, the
proposed models outperforms the most well-known model chemistries, reaching a
subchemical accuracy without any empirical parameter and with affordable computer
times. Besides the composite schemes development efforts, a robust protocol
for disclosing the thermochemistry and kinetics of reactions of atmospheric and astrophysical
interest, rooted in the so-called ab initio-transition-state-theory-based master equation approach have been thoroughly investigated and validated.
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Farrugia, Josette. "An investigation of 16 to 18-year-old students' difficulties with thermochemistry calculations." Thesis, University of York, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399634.
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Bates, Richard Burton. "Modeling the coupled effects of heat transfer. thermochemistry, and kinetics during biomass torrefaction." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70433.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012."February 2012." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 167-174).
Torrefaction is a thermal pretreatment process which improves the energy density, storage, grinding, and handling characteristics of raw biomass. Research efforts to date have focused on empirical measurements of the fuel quality improvements caused by torrefaction at different temperature and residence time conditions. Additionally, these efforts have assumed that torrefaction is a kinetically limited process and do not account for heat transfer limitations present in larger particles. The first component of the present torrefaction model is an analysis of the existing experimental work which results in a detailed thermochemical and grinding energy models. These models enable the prediction of reaction mass, energy, and species balance as well as torrefied product characteristics such as grindability and heating value over a wide range of reactor conditions. Based on this framework, optimal conversion conditions are determined. The second component of the present work is a numerical unsteady one-dimensional single particle model where conservation equations are solved by a custom code in MATLAB. The effects of coupled thermochemical, kinetic, and heat transfer phenomena are analyzed. A comparison of two classes of torrefaction reactors (fixed/moving bed and fluidized bed) is made based on simulation results.
by Richard Burton Bates.
S.M.
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Mabrouki, Ridha Ben Mohsen. "Drift Tube Ion Mobility Measurements for Thermochemistry, Kinetics and Polymerization of Cluster Ions." VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd/1165.
Full textAbstract:
In this work, the Drift Tube Ion Mobility technique is used to study the hydrophobic hydration and solvation of organic ions and measure the thermochemistry and kinetics of ion-molecule reactions. Furthermore, an exploratory study of the intracluster polymerization of isoprene will be presented and discussed. The ion hydration study is focused on the C3H3+ cation1 and Pyridine▪+ radical cation.2 The chemistry of the cyclic C3H3+ cation1 has received considerable attention and continues to be an active area of research.3-7 The binding energies of the first 5 H2O molecules to c-C3H3+ were determined by equilibrium measurements. The measured binding energies of the hydrated clusters of 9-12 kcal/mol are typical of carbon-based CH+X hydrogen bonds. The ion solvation with the more polar CH3CN molecules results in stronger bonds consistent with the increased ion-dipole interaction. Ab initio calculations show that the lowest energy isomer of the c-C3H3+(H2O)4 cluster consists of a cyclic water tetramer interacting with the c-C3H3+ ion, which suggests the presence of orientational restraint of the water molecules consistent with the observed large entropy loss. The c-C3H3+ ion is deprotonated by 3 or more H2O molecules, driven energetically by the association of the solvent molecules to form strongly hydrogen bonded (H2O)nH+ clusters. The kinetics of the associative proton transfer (APT) reaction C3H3+ + nH2O → (H2O)nH+ + C3H2 exhibits an unusually steep negative temperature coefficient of k = cT(sup>63±4 (or activation energy of -32 ± 1 kcal mol-1). The behavior of the C3H3+/water system is exactly analogous to the benzene+ /water system8,9, suggesting that the mechanism, kinetics and large negative temperature coefficients may be general to multibody APT reactions. These reactions can become fast at low temperatures, allowing ionized polycyclic aromatics to initiate ice formation in cold astrochemical environments.The solvation energies of the pyridine+ radical cation by 1- 4 H2O molecules are determined by equilibrium measurements in the drift cell. The binding energies of the pyridine+(H2O)n clusters are similar to the binding energies of protonated pyridineH+(H2O)n clusters that involve NH+∙∙OH2 bonds, and different from those of the solvated radical benzene+(H2O)n ions that involve CHδ+∙∙OH2 bonds. These relations indicate that the observed pyridine+ ions have the distonic C5H4NH+ structure that can form NH+∙∙OH2 bonds. The observed thermochemistry and ab initio calculations show that these bonds are not affected significantly by an unpaired electron at another site of the ion. The distonic structure is also consistent with the reactivity of pyridine+ in H atom transfer, intra-cluster proton transfer and deprotonation reactions. The results present the first measured stepwise solvation energies of distonic ions, and demonstrate that cluster thermochemistry can identify distonic structures.The gas phase clustering of small molecules around the hydronium ion is of fundamental interest and is relevant to important atmospheric and astrophysical processes. In this work, the equilibrium constants for the formation of the H3O+(X)n clusters with X = H2, N2 and CO and n = 1-3 at different temperatures are measured using the drift tube technique10. The arrival time distributions (ATDs) of the injected H3O+ and the H3O+(X)n clusters formed inside the cell are measured under equilibrium conditions. The resulting binding energies for the addition of one and two hydrogen molecules are similar [3.4 and 3.5 kcal/mol, respectively). For the N2 clustering with n = 1-3, the measured binding energies are 7.9, 6.9 and 5.4 kcal/mol, respectively. The clustering of CO on the H3O+ ion exhibits a relatively strong binding energy (11.5 kcal/mol) consistent with the dipole moment and polarizability of the CO molecule. Theoretical calculations of the lowest energy structures are correlated to the experimental results. Finally, intracluster polymerization leading to the formation of covalent bonded oligomer ions has been investigated following the ionization of neutral isoprene clusters. The results indicate that isoprene dimer cation has a structure similar to that of the limonene radical cation. Mass-selected mobility and dissociation studies also indicate that the larger isoprene cluster ions have covalent bonded structures. The conversion of molecular clusters into size-selected oligomers is an important process not only for detailed understanding of the early stages of polymerization but also for practical applications such as the formation of new polymeric materials with controlled and unusual properties.
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Jones, S. A. "Characterisation and thermal analysis of antimony(III) oxy-compounds." Thesis, Liverpool John Moores University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380656.
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McCollam, Bridget E. "Thermochemistry of a synthetic Na-Mg rich triple-chain silicate determination of thermodynamic variables and geological applications /." Diss., Online access via UMI:, 2007.
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Ozkan, Ibrahim Ali. "Thermodynamic model for associating polymer solutions." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-05042004-142825/unrestricted/ozkan%5Fibrahim%5Fa%5F200408%5Fphd.pdf.
Full textAbstract:
Thesis (Ph. D.)--School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2005. Directed by Amyn S. Teja.Dr. Thomas H. Sanders, Committee Member ; Dr. Peter J. Ludovice, Committee Member ; Dr. J. Carson Meredith, Committee Member ; Dr. William J. Koros, Committee Member ; Dr. Amyn S. Teja, Committee Chair. Includes bibliographical references.
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Sebbar, Nadia [Verfasser]. "Thermochemistry and kinetics for the oxidative degradation of dibenzofuran and precursors / by Nadia Sebbar." Karlsruhe : Univ.-Verl. Karlsruhe, 2007. http://d-nb.info/983197482/34.
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Ng, Dixon C. "Wood liquefaction with hydriodic acid." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65993.
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Petrucelli, Giovanni Cavichioli. "Sintese, caracterização e termoquimica de materiais lamelares nanoestruturados derivados de magadeita." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250087.
Full textAbstract:
Orientador: Claudio AiroldiTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: O composto lamelar magadeíta foi hidrotérmicamente sintetizado na forma (Na2Si14O29.9H2O) [Namag], que ao ser tratado com HCl 0.10 mol dm gerou [Hmag]. O nanocomposto hidratado ácido silícico lamelar magadeíta [Hmag] (H2Si14O29.2H2O), foi utilizado na intercalação de alquilaminas polares de fórmula geral H3C(CH2)nNH2 (n=1-6) em solução aquosa. A distância interlamelar (d) original da [Hmag] de 1150 pm, apresenta aumento com a intercalação, dando correlações com o número de átomos carbonos da amina alifática (nc): d = [(1313±15) + 20±3)]nc. A quantidade de amina intercalada (Ns) diminui com o aumento de nc: Ns = [(5,87±0,12) ¿ (0,43±0,03)]nc. Os resultados de titulação calorimétrica deram correlações termodinâmicas com a entalpia: DintH = -[(24,45±0,49) ¿ (1,91±0,10)]nc e d = [(1576±16) ¿ (11±1)]DintH. Os valores negativos da energia livre de Gibbs e positivos para entropia deram as correlações: DintG = -[(22,3±0,2) ¿ (0,5±0,1)]nc and DintS = [(6±1) + (5±1)]nc, respectivamente. A forma ácida [Hmag] foi modificada quimicamente com [3- aminopropiltrimetoxissilano (1N), N-3-trimetoxissililpropiletilenodiamina (2N), N-3-trimetoxissililpropiletilenotriamina (3N) e 3-mercaptopropiltrimetoxissilano (1S)]. Os materiais sintetizados foram caracterizados por difração de raios-X, espectroscopia na região do infravermelho, RMN no estado sólido de Na, Si and C, área superficial, volume de poro e termogravimetria. A quantidade de agente sililante incorporada foi determinada por análise elementar resultando em: (2,34±0,18), (1,96±0,18), (1,25±0,11) e (1,45±0,12) mmol g, respectivamente. O número de moles dos cátions divalentes adsorvidos (Co, Ni, Cu, Zn, Cd e Hg) foi determinado através do processo de batelada e ajustado ao modelo de Langmuir. Os efeitos térmicos da interação cátions centros básicos existentes nas cadeias xiv pendentes foram determinados por titulação calorimétrica na interface sólido/líquido. Os valores entálpicos são exotérmicos, de energia livre de Gibbs e entropia negativos e positivos, respectivamente, indicando que os efeitos interativos são termodinamicamente favorecidos. Os espectros de XANES e EXAFS indicam que átomos de cobre são adsorvidos por 1N e 1S resultando em octaédros com diferentes graus de distorção. O Cu-1Nmag apresenta similaridade estrutural ao CuO de acordo com o padrão de Cu(OH)2 com quatro ligações equatoriais e duas axiais. A simulação de EXAFS para a segunda esfera de coordenação está associada ao efeito de interação com um cátion de cobre adjacente, sugerindo que o cobre está coordenado como cluster multinucleares, como resultado de uma precipitação inicial de monômero, seguida pela formação de um cluster com ponte de hidróxido
Abstract: Layered compounds magadiite was hydrothermically synthesized (Na2Si14O29.9H2O) [Namag] end treated with HCl 0.10 moldm gerou [Hmag]. The hydrated lamellar nanocompound acidic silicic magadiite [Hmag] (H2Si14O29.2H2O), was used as host for intercalation in aqueous solution of polar alkylmonoamine molecules of the general formula H3C(CH2)nNH2 (n=1-6). The original interlayer distance (d) of 1150 pm, by [Hmag], increases after intercalation, resulting on values correlated with the number of the carbons atoms of aliphatic amine (nc): d = [(1313±15) + 20±3)]nc. The amount of intercalated amines (Ns) decreased as nc increased: Ns = [(5,87±0,12) ¿ (0,43±0,03)]nc. The calorimetric titration results for enthalpy data gave thermodynamic correlations:: DintH = -[(24,45±0,49) ¿ (1,91±0,10)]nc and d = [(1576±16) ¿ (11±1)]DintH. The negative Gibbs energy values and positive entropies also presented the correlations: DintG = -[(22,3±0,2) ¿ (0,5±0,1)]nc and DintS = [(6±1) + (5±1)]nc, respectively. The acides [Hmag] form was chemically modified with: [3- trimethoxysily(propylamine)] (1N), [N-(3-trimethoxysilil)propyl)etylenediamine] (2N), [N-3-trimethoxysililpropyl(etylenetriamine)] 3N and [3-trimetoxysilmercaptopropyltrimethoxysilane] (1S). The synthesized materials were characterized by X-ray powder diffraction, infrared spectroscopy, Na, Si and C, NMR in solid state, surface area, pore volume and thermogravimetry. The amounts of silylating agent immobilized were determined from elemental analyses to give: 2.34±0.18, 1.96±0.18, 1.25±0.11 and 1.45±0.12 mmol g, respectively. The number of moles divalents cations (Co, Ni, Cu, Zn, Cd and Hg) adsorbed was obtained for batch wise procedure and the data was adjusted to Langmuir model. xvi The thermal effects of cation basic centers on pendant chains interactions were obtained through calorimetric titration at the solid/liquid interface. The exothermic enthalpy, the negative Gibbs free energy and positive entropy values, are in agreement are thermodynamically favorable for these interaction. The XANES and EXAFS spectra indicated that copper atoms were adsorbed on 1N and 1S layered materials resulting in octahedron structure with different degree of distortions. Cu- 1Nmag resembled the CuO unit from Cu(OH)2 model with similar four equatorial and two axial Cu-O distances. The EXAFS simulation of the second sphere associated with Cu-Cu bond for materials that suggested the coordinated metal in multinuclear clusters on the surface, as a result of the initial monomer precipitation that growth from the formation hydroxo-bridged clusters
Doutorado
Quimica Inorganica
Doutor em Ciências
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Krishnamurthy, Harini. "Analysis of rigidity, stability, and activity in Thermotoga neapolitana adenylate kinase." Diss., Connect to online resource - MSU authorized users, 2006.
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Sure, Rebecca [Verfasser]. "Evaluation and Development of Quantum Chemical Methodologies for Noncovalent Interactions and Supramolecular Thermochemistry / Rebecca Sure." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1096329867/34.
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Covert, Kyle John. "Roaming Transition States and Highly Accurate Thermochemistry: A PEPICO Study of Two Small Combustion Systems." Scholarly Commons, 2019. https://scholarlycommons.pacific.edu/uop_etds/3624.
Full textAbstract:
Two small combustion systems, methyl hydroperoxide (CH3OOH) and 2-propanol ((CH3)2CHOH), were studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO), which combines photoelectron spectroscopy and photoionization mass spectrometry to detect coincident photoelectron-photoion pairs. In the photon energy range of 11.4–14.0 eV, energy selected CH3OOH+ ions dissociate into CH2OOH+, HCO+, CH3+, and H3O+ ions. The lowest-energy dissociation channel is the formation of the cation of the smallest “QOOH” radical, CH2OOH+. A statistical rate model fitted to the experimental data yields a 0 K appearance energy of 11.647 ± 0.005 eV for the CH2OOH+ ion, and a 74.2 ± 2.6 kJ mol–1 mixed experimental-theoretical 0 K heat of formation for the CH2OOH radical. The proton affinity of the Criegee intermediate, CH2OO, was also obtained from the heat of formation of CH2OOH+ (792.8 ± 0.9 kJ mol–1) to be 847.7 ± 1.1 kJ mol–1, reducing the uncertainty of the previously available computational value by a factor of 4. RRKM modeling of the higher-energy fragmentation processes, supported by Born–Oppenheimer molecular dynamics simulations, found that the HCO+ fragment ion is produced through a roaming transition state; H3O+ is formed in a consecutive process from the CH2OOH+ fragment ion; and direct C–O fission of the molecular ion leads to the methyl cation. Experimentally, 2-propanol has been found to dissociate primarily into CH2CHOH+, CH3CHOH+, CH3CHCH3+, and, as a minor product, into (CH3)2COH+ ions within a photon energy range of 10.0–13.1eV. There are interesting dissociation dynamics involving breaking the C–¬C bond: the lowest energy product (CH3 loss) is quickly outcompeted by a kinetically favored CH4 loss. At low internal energies of < 0.3 eV, the loss of CH4 dominates through a roaming pathway, when the leaving CH3 abstracts a hydrogen atom from the other methyl group. At higher energy, the direct loss of CH3• quickly takes over as its transition state is much less tight and, thus, it is kinetically favored. The statistical model fitted to the experimental data yielded the appearance energy corresponding to the thermochemical limit for the CH3-loss dissociation and the 0 K heats of formation of the CH3CHOH+ ion was found to be in good agreement with ATcT values and with our previous study on ethanol.
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Peshek, Timothy John. "Studies in the Growth and Properties of ZnGeN2 and the Thermochemistry of GaN." online version, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=case1207231457.
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Lee, Matthew Colin John. "Correlations between MO Eigenvectors and the Thermochemistry of Simple Organic Molecules, Related to Empirical Bond Additivity Schemes." The University of Waikato, 2008. http://hdl.handle.net/10289/2623.
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A bondingness term is further developed to aid in heat of formation (ΔfHº) calculations for C, N, O and S containing molecules. Bondingness originated from qualitative investigations into the antibonding effect in the occupied MOs of ethane. Previous work used a single parameter for bondingness to calculate ΔfHº in an alkane homologous series using an additivity scheme. This work modifies the bondingness algorithm and uses the term to parameterise a test group of 345 molecules consisting of 17 subgroups that include alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, amides, diazenes, nitriles, nitroalkanes, nitrates, thiols and benzenoids. Comparing experimental with calculated ΔfHº values, a standard deviation for the residuals of 6.3 kJ mol 1 can be achieved using bondingness with a simple steric repulsion term (SSR) in a bond additivity scheme, and a standard deviation of 5.2 kJ mol 1 can be achieved using a Lennard-Jones potential. The method is compared with the group method of Pedley, which for a slightly smaller set of 338 molecules, a subset of the test set of 345 molecules, gives a standard deviation of 7.0 kJ mol 1. Bondingness, along with SSR or a Lennard-Jones potential, is parameterised in the lowest level of ab initio (HF-SCF) or semiempirical quantum chemical calculations. It therefore may be useful in determining the ΔfHº values for the largest molecules that are amenable to quantum chemical calculation. As part of our analysis we calculated the difference between the lowest energy conformer and the average energy of a mixture populated with higher energy conformers. This is the difference between the experimental ΔfHº value and the ΔfHº calculated for a single conformer. Example calculations which we have followed are given by Dale and Eliel et al.. Dale calculates the energy difference for molecules as large as hexane using relative energies based on the number of 1,4 gauche interactions. We have updated these values with constant increments ascertained by Klauda et al. as well as ab initio MP2 cc-pVDZ relative energies and have included calculations for heptane and octane.
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Peck, Michael S. "Materials study supporting thermochemical hydrogen cycle sulfuric acid decomposer design." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4860.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Feb. 27, 2008). Vita. Includes bibliographical references.
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Ramos, Gustavo Roberto. "Relaxação exotérmica e recristalização endotérmica do tungstato de zircônio amorfo." reponame:Repositório Institucional da UCS, 2011. https://repositorio.ucs.br/handle/11338/1069.
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Rugunanan, Rajan Anil. "Intersolid pyrotechnic reactions of silicon." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1015571.
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A study of the role of different oxidants with silicon as the fuel in simple binary pyrotechnic compositions is reported. Several oxidants were examined, but only three (Sb₂0₃, Fe₂0₃ and Sn0₂) satisfied the restrictions that the combustion temperatures should be below the melting point of platinum/rhodium thermocouples (1760°C), that burning rates should not exceed the response of the thermocouples, and that burning should occur without significant mass-transport. A fourth oxidant, KN0₃, was selected on account of its low melting point and general importance as a pyrotechnic oxidant. The oxidation of silicon in the presence of either Sb₂0₃ or KN0₃ could be identified from thermal analysis curves. No thermal events were noted when Si/Sn0₂ and SiFe₂0₃ compositions were heated under similar conditions. The oxidation of Si powder in oxygen was also studied. All four binary systems sustained burning over a reasonably wide range of compositions. The range of burning rates measured (2 to 35 mm s⁻¹) depended on the oxidant used. Fe₂0₃ and Sb₂0₃ gave slow burning mixtures compared to Sn0₂ and to KN0₃ compositions with a high Si content. Burning rates generally increased with increasing specific surface area of silicon, but decreased in the presence of inert diluents and moisture. The burning rates of the Si/Fe₂0₃ and Si/Sn0₂ systems increased with increasing compaction of the samples. Kinetic parameters derived from the temperature proftles recorded during combustion were generally low (6 to 37 kJ mol⁻¹). This is in keeping with proposals that burning is diffusion controlled. The values of kinetic parameters derived from thermal analysis curves were considerably greater ( > 250 kJ mol⁻¹). Two other fuels, FeSi₇ and CaSi₂, gave similar thermal analysis curves when used instead of silicon. There were considerable differences in the burning rates for binary mixtures of these fuels compared to silicon. Ternary systems with two fuels or two oxidants showed that only limited interaction occurs during thermal analysis. The use of a second fuel or oxidant did, however, modify the burning behaviour considerably. Other techniques used in this study to probe the details of the reaction processes included bomb calorimetry, measurement of thermal conductivities, infrared spectroscopy, X-ray diffraction and scanning electron micoscropy.
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Sanderson, Simon R. "Shock wave interaction in hypervelocity flow /." Web site:, 1995. http://etd.caltech.edu/etd/available/etd-11092004-094744/.
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Milovanovic, Milan. "Experimental and theoretical approaches coupled with thermochemistry of reactions in solution and the role of non-covalent interactions." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAF049.
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Ce manuscrit aborde plusieurs interactions / réactions chimiques importantes se produisant dans la soluton en utilisant la calorimétrie par titrage isothermique (ITC) et la théorie de la densité fonctionnelle statique (DFT). Cette thèse porte son attention notamment sur : l'association de paires de Lewis (frustrées) ((F)LPs), la migration cis du groupe méthyle au sein du pentaméthylmanganèse induit par les phosphines, l'aminolyse de carbènes de Fischer, l'insertion d'alcynes dans des palladacycles, l'affinité de divers donneurs de Lewis à l’hexafluoroisopropanol. L'ITC s'est révélé être une technique expérimentale puissante pour obtenir des données thermochimiques fiables sur les systèmes étudiés. Les calculs statiques DFT-D ont montré une capacité d’estimation correcte des paramètres de réaction thermodynamique lorsque l’influence de la solvatation n’est pas significative. Autrement, lorsque l’influence du solvant est apparente, les calculs ne permettent pas de reproduire les résultats expérimentaux. En plus, les résultats expérimentaux et théoriques révèlent l’existence d’ensembles moléculaires plus grandes dans la solution de FLP, soulignant le rôle des interactions non covalentesThis manuscript adressed several important chemical interactions/reactions taking place in solutuon by using Isothermal Titration Calorimetry (ITC) and static Density Functional Theory (DFT). Namely, this thesis dealt with: association of (frustrated) Lewis pairs ((F)LPs), cis-migration of methyl group within pentamethylmanganese induced by phosphines, aminolysis of Fischer carbenes, insertion of alkynes into palladacycles, affinity of various Lewis donors to hexafluoroisopropanol. The ITC proved to be powerful experimental technique for obteining reliable thermochemical data of sutudied systems. The static DFT-D calculations showed capability for proper estiamtion of thermodynamic reaction parameters when an influence of solvation is not sighnificant. Otherwise, when the influence of solvent is not innocent, the calculations moslty failed to reproduce the experimantal results. In addition, Both the experimantal and therortical results revield existance of larger molecular clusters in solution of FLPs emphasising a role of non-covalent interactions