Submitted by Kamila Ferreira Prado null (kamilafprado@hotmail.com) on 2016-05-30T18:35:04Z No. of bitstreams: 1 DISSERTAÇÃO KAMILA FERREIRA PRADO - LIVROS DIDÁTICOS E CONCEPÇÕES DE PROFESSORES - A HISTÓRIA DA CIÊNCIA NO ENSINO DE EQUILÍBRIO QUÍMICO.pdf: 1460005 bytes, checksum: e3d8ed2342936b2817268b1825affcbc (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-31T16:49:21Z (GMT) No. of bitstreams: 1 prado_kf_me_bauru.pdf: 1460005 bytes, checksum: e3d8ed2342936b2817268b1825affcbc (MD5) / Made available in DSpace on 2016-05-31T16:49:21Z (GMT). No. of bitstreams: 1 prado_kf_me_bauru.pdf: 1460005 bytes, checksum: e3d8ed2342936b2817268b1825affcbc (MD5) Previous issue date: 2016-03-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A Química é considerada uma Ciência difícil de ser estudada e compreendida pelos alunos e suas concepções prévias atuam como verdadeiros obstáculos à aprendizagem. Neste contexto, o tema Equilíbrio Químico é considerado como um dos tópicos mais complexos e exigentes no Ensino Médio ou em cursos introdutórios de Química no Ensino Superior. Este trabalho tem como objetivo a análise da estruturação do conceito de Equilíbrio Químico do ponto de vista da História da Ciência em livros didáticos utilizados por professores no Ensino Médio e análise das concepções e conhecimentos que os professores possuem sobre a utilização da História da Ciência no ensino deste tema. Um questionário foi aplicado a 10 professores da Rede Pública Estadual de ensino buscando verificar qual a formação dos professores para o uso da História da Ciência no ensino do conceito de Equilíbrio Químico. Foram também analisados os capítulos correspondentes ao tema nos livros didáticos indicados pelo PNLEM e nos cadernos da Secretaria Estadual de Educação de São Paulo, adotados no Ensino Médio para o planejamento e complemento das aulas. Os resultados mostram que os professores não foram formados adequadamente na licenciatura para o uso de História da Ciência, assim eles não se sentem preparados para utilizar tal abordagem, além destes fatores, os livros didáticos analisados incorporam uma visão simplista dos conceitos relacionados ao tema, apresentando em seus textos abordagens superficiais de historiografia. / The chemistry is considered a difficult Science to be studied and understood by students and their prior conceptions act as real obstacles to learning. In this context, the Chemical Equilibrium theme is regarded as one of the most complex and demanding topics in high school or introductory Chemistry courses in Higher Education. This study aims to analyze the structure of the concept of Chemical Equilibrium in terms of the History of Science in textbooks used by high school teachers and analysis of conceptions and knowledge that teachers have about the use of the History of Science in teaching this theme. A questionnaire was applied to 10 public school teachers teaching State seeking to check what the training of teachers to the use of the history of science in the teaching of the concept of chemical equilibrium. Were also analyzed the chapters corresponding to the subject in the textbooks listed at PNLEM and on the rolls of the State Secretariat of Education of São Paulo, adopted in high school for planning and add-on. The results show that the teachers have not been trained properly in degree to the use of the History of Science, so they do not feel prepared to use such an approach, in addition to these factors, the textbooks analyzed incorporate a simplistic vision of the concepts related to the topic, showing in his writings superficial approaches of historiography.

Muitas áreas da indústria utilizam substanciais somas de energia térmica, geralmente obtida pela combustão de óleo, gás ou carvão. Na queima destes combustíveis geralmente é utilizado ar como oxidante, que é constituído aproximadamente por 21% de O2 e 79% de N2, em volume. Em muitos casos, os processos de combustão podem ser enriquecidos com o uso de oxidantes que possuem concentrações de oxigênio maior que a existente no ar. Isto é conhecido como combustão enriquecida com oxigênio (OEC) que pode trazer vários benefícios como a redução do consumo de combustíveis, aumento da energia térmica disponível, redução no volume dos gases de combustão, baixo custo de adaptação dos equipamentos existentes, entre outros. Com este cenário, o presente trabalho investiga o uso da combustão enriquecida com oxigênio em uma turbina a gás industriais de um eixo. O equipamento foi modelado termodinamicamente e com a consideração que os gases de combustão formados se encontram em equilíbrio químico. Dessa forma, são estudadas três formas de operação da turbina a gás com o uso do processo de enriquecimento da combustão, que são: 1) vazão de ar de admissão constante, 2) potência líquida constante com rotação fixa e 3) potência líquida constante com rotação variável. Os resultados mostram que pode ser obtido um aumento de até 143% na potência líquida e de 24% no rendimento térmico do ciclo para o caso 1. Entretanto, é necessária uma substancial soma de oxigênio para sustentar o processo. / Many industry areas use large amounts of thermal energy, usually obtained by burning oil, gas or coal. The combustion of these fuels generally used air as an oxidant, which consists of approximately 21% O2 and 79% N2, in volume. In many cases, combustion processes can be enriched with the use of oxidants with higher concentration of oxygen than present in the air. This is known as oxygen-enhanced combustion (OEC), which can provide several benefits such as reduced fuel consumption, increased thermal energy availability, reduction in flue gas volume, low retrofitting cost and others. With this background, this work investigates the use of oxygen-enhanced combustion in heavy duty single-shaft gas turbine. The equipment was thermodynamically modeled and the consideration that the combustion gases are in chemical equilibrium. Thus, three possible ways of implementation of the enrichment process of combustion were studied, which are: 1) constant intake air flow, 2) constant net power with fixed rotation and 3) constant net power with variable speed. The results showed that one can be obtained up to 143% increase in net power and 24% in thermal efficiency of the cycle in case 1. However, it’s necessary a substantial amount of oxygen to sustain the OEC process.

Fez-se um estudo monográfico das características gerais dos pseudo-haletos - pseudo-halogênios por estarem ligados aos estudos experimentais relatados na presente tese. Estudaram-se novos procedimentos para determinação de constantes de equilíbrio (baseados na linearização de curvas) e para obtenção de αo em regiões experimentalmente inacessíveis do ligante. Esses procedimentos foram exaustivamente testados em sistemas modelos antes de serem aplicados à solução de sistemas reais, com base experimental. O sistema Cu(II)/Br- foi estudado espectrofotometricamente, com tratamento iterativo dos dados experimentais, chegando-se às seguintes constantes de formação e absortividades molares dos três complexos: (Ver no arquivo em PDF). Relações lineares forum observadas para -ε vs. -n. Nova sistemática de medidas precisas de E1/2 da segunda onda de cobre(II) em azoteto e brometo (separação pouco definida das duas etapas), permitiu estudar com maior exatidão os complexos formados relativos a esses sistemas: (Ver no arquivo em PDF). Diagramas de potenciais envolvendo os sistemas Cu(II)/Cuo, Cu(I)/Cuo e Cu(II)/Cu(I), em meio de brometo e azoteto, permitiram tirar conclusões interessantes, especialmente, sobre o comportamento potenciométrico do eletrodo de membrana de CuS e Ag2S em presença de ânions N-3; e Br-. Observações preliminares foram feitas sobre o aparecimento de ondas catalíticas envolvendo peróxido de hidrogênio e o amálgama de cobre, formado na superfície do eletrodo gotejante. As experiências evidenciaram que o ciclo catalítico envolve a oxidação do amálgama a cobre(I) e cobre(II). Consideráveis diferenças de comportamento foram observadas entre os eletró1itos suportes de azoteto e acetato. No estudo polarográfico do sistema Cu(II)/Cu(Hg) em acetato, chegou-se a um processo conveniente de obtenção do E1/2 reversível por extrapolação à densidade de corrente zero. / A mono graphic study of the pseudohalide or pseudohalogen characteristics was done in order to better understand some experimental studies performed. New processes of determination of equilibrium constants were considered for treatment of experimental data. They consist in linearization of curves and achievement of experimental data of αo vs. ΙLΙ experimentally unaccessible regions of the ligand. The procedures were exaustively checked in model systems before its aplication to real systems. The copper(II)/bromide system was studied by spectrophotometry by an iterative treatment of experimental data of average molar absortivities. The formation constants and molar absortivities of the three detected complexes are: (See in the PDF file) Linear relationships were observed between the average molar absortivities and average ligand number. The polarographic study confirmed the stepwise reduction of copper(II) in bromide suporting electrolite. The following formation constants of the copper(I)-bromide complexes were obtained: (See in the PDF file). A new procedure for precise E1/2 measurements in the two copper waves in azide and bromide medium was applied at conditions where low definition between the two waves occurs. This permits to find more reliable equilibrium constants for the copper(I)/azide system: (See in the PDF file). Potential diagrams refered to the Cu(II)/Cuo, Cu(I)/Cuo and Cu(II)/Cu(I) systems in bromide and azide medium led to interesting conclusion, specially refered to the potentiometric behavior of a membrane selective electrode of CuS and Ag2S, in the presence of bromide and azide anions. Preliminary results were taken the existence of catalytic waves involving hidrogen peroxide and the copper amalgam formed at the dropping mercury electrode. The catalytic cicle is achieved through the oxidation of the amalgan to copper(I) and copper(II) by the peroxide in alkaline medium. Considerable differences were observed between the azide and acetate supporting electrolite.

Orientador: Adriana Vitorino Rossi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-12T12:44:57Z (GMT). No. of bitstreams: 1 Verzoto_JoseCarlos_M.pdf: 2173357 bytes, checksum: 93e5222b6474774989fc07e35aeec890 (MD5) Previous issue date: 2008 / Resumo: Neste trabalho, o tema equilíbrio químico foi objeto de estudo sob perspectiva didática, considerando-se sua relevância em termos conceituais bem como aspectos relacionados ao processo de ensino/aprendizagem, como dificuldades apresentadas na linguagem e interpretação desse conceito apontadas na literatura e por professores do ensino médio. Neste contexto, buscou-se investigar aspectos de desenvolvimento histórico desse conceito, resgatando informações relevantes para subsidiar interpretações críticas de material didático comercial e aprimorar situações propícias ao processo de ensino/aprendizagem em sala de aula. Paralelamente, foram elaboradas e testadas duas propostas didáticas. A primeira proposta A envolveu a elaboração de material de apoio para o ensino de equilíbrio químico incluindo aulas contextualizadas, demonstrações experimentais e abordagem histórica e esta foi aplicada a três turmas de estudantes (81 participantes) da 3ª série em 2007. A outra proposta B limitou-se a aspectos teóricos tradicionais e foi aplicada a nove turmas (236 estudantes) da 2ª e 3ª série em 2006 e 1 turma com 33 estudantes da 3ª série, em 2007, todas do ensino médio. Utilizando-se questionários e entrevistas, foram investigadas impressões prévias e pós-aulas desses estudantes sobre questões envolvendo o conceito de equilíbrio químico. Os resultados desta investigação indicaram vantagens no processo de ensino/aprendizagem na aplicação da proposta A, que incluiu situações que oportunizaram o professor discutir alguns aspectos concretos incluindo demonstração experimental e mostrando aspectos positivos na discussão da construção do conhecimento científico sob uma perspectiva histórica e o crescimento dinâmico da Ciência. Apesar dessa proposta demandar alguns esforços adicionais para o professor, principalmente referindo-se as demonstrações experimentais e discussão de aspectos históricos, os resultados alcançados são compensadores. / Abstract: In this work, the subject chemical equilibrium was the object of study under didactic perspective, considering its relevance in conceptual terms as well as aspects related to the teaching/learning process, as difficulties presented in the language and interpretation of this concept pointed in the literature and by high school teachers. In this context, aspects of historical development of this concept were investigated in order to recovery important information to subsidize a critical evaluation of commercial textbooks and to improve propitious situations the teaching/learning process in the classroom. At the same time, two didactic proposals were elaborated and tested. The first proposal A involved the elaboration of the support material for teaching chemical equilibrium including contextualized lessons, experimental demonstrations and historical approaching and it was applied to three groups of students (81 participants) of 3rd grade in 2007. The other proposal B was limited to the traditional theoretical aspects and was applied to nine groups (236 students) of 2rd and 3rd grades in 2006 and one group with 33 students of 3rd grade, in 2007, all of high school. Written questionnaires and interviews were to investigate previous and after-lessons conceptions of these students on questions involving the concept of chemical equilibrium. The results of this study indicated advantages in the process of teaching/learning in the application of the proposal A, that included situations that became opportune to the professor to the discuss some concrete aspects including experimental demonstration and I also showed the positive effect of talk about how the scientific knowledge is built under a historical perspective and the dynamic growing of the Science. Despite of this proposal demanding some additional efforts from the professor, mainly concerning to the experimental demonstrations and quarrel of historical aspects, the reached results are compensating. / Mestrado / Quimica Analitica / Mestre em Química

D.Ed. (Didactics) / This study focused on the misconceptions which exist among standerd ten pupils in the field of chemical equilibrium and the rate of chemical reactions. Although the teacher Is confident that meaningful teaching occurs In the classroom situation, misconceptions do materialise frequently. Several factors concerning the pupil, the teacher as well as the subject content Itself were Investigated. The main objective of this study Is to Investigate the nature and extent of the misconceptions regarding the rate of chemical reactions and the chemical equilibrium experienced by standard ten pupils. Following this, pupils are exposed to a computer program which has been complied to eliminate the misconceptions regarding these two themes...

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Geology and Geophysics, 1967. / Vita. / Bibliography: leaves [179]-[187]. / by William Howard Blackburn, Jr. / Ph.D.

Intravenous admixtures consisting of one or more drug formulations, diluted in a large volume of intravenous solution, are used extensively in current medical practice. Development of reliable methods to predict the compatibility of the admixture components is essential as a guide for their selection. Because the majority of the reports published, to date, have used a visible change as the criterion for judging compatibility, it was the purpose of this study to demonstrate the use of spectrophotometric analysis to detect the occurrence of chemical interactions between two components of an intravenous admixture.

Thermal methods were used, to determine with high precision, the solid-liquid phase equilibria diagrams for the sodium-rubidium and sodium-potassium-rubidium systems. In the sodium-rubidium system, the results differ greatly from those of earlier works, especially near the eutectic composition where differences in freezing points as large as 25°K occur. A detailed search was made for possible intermetallic compounds (especially Na2Rb). Neither slow temperature cycling in the temperature range where compound formation could occur nor extended periods of annealing just above the eutectic temperature produced any evidence for compound formation in the sodium-rubidium system. A 2:1 (sodium to rubidium) sample was subjected to 60,000 atmospheres pressure. Again, no evidence was obtained for solid compound formation. In the sodium-potassium-rubidium system, a partial phase diagram was obtained; however, there. is no evidence of the formation of NaKRb in this system.

The use of supported catalysts to essentially combine the positive traits offered by both homogeneous and heterogeneous catalysis has become a competitive field of research. In particular, hydrotalcite-like catalysts (HTIc) has proven to be valuable for this purpose. Various osmium - containing catalysts were synthesized according to the co-precipitation method viz. Os-Cu-HTIc, Os-Ni-HTlc and the Os-Co-HTlc. Techniques such as SEM, IR, EDS, XRD, ICP, BET and XPS were exploited during catalyst characterisation and these essentially confirm that the hydrotalcite (HT) structure has been obtained. Various olefin substrates, ranging from simple straight-chained alkenes to cyclic, allylic and halogenated olefins, were tested. The results are promising and suggest that the diols are produced both with high selectivity and in good yield. Further experiments suggest: 1) Ofthe various co-oxidants tested, N-methylmorpholine-N-oxide is most suitable 2) The reaction proceeds faster at 60 °C than at room temperature 3) The addition of water to the reaction mixture increases the rate of the reaction for most substrates and 4) The catalyst is thermally stable and produces better results when calcined at 200 0 C prior to use This thesis reports that a new heterogeneous catalytic system for the efficient and selective cisdihydroxylation of olefins has been developed - one which suggests no leaching of metal into the reaction solution and no over-oxidation products. / Thesis (M.Sc.)-University of KwaZulu Natal, 2004.

Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Humanities, School of Education, 2012 / Reflection about lessons delivered is a practice widely encouraged in teaching. Reasoning, particularly about transformation of subject matter knowledge of lessons yet to be taught, is an internal process and a speciality evident largely in expert teachers. The study investigates the feasibility of fast-tracking its development in pre-service chemistry teachers. It focuses on developing this specialty within a specific topic, as a theoretical construct called Topic Specific PCK (TSPCK). Five knowledge components of TSPCK are identified as the enablers that transform subject matter knowledge. The components are: (1) students’ prior knowledge, (2) curricular Saliency, (3) what is difficult to teach (4) representations, including powerful analogies, and (5) conceptual teaching strategies. These components are identified, with reference to literature, as aspects specific to the subject matter knowledge of the teacher and useful in its teachability. A new tool to measure the quality of TSPCK is developed. The procedure for developing the tool consists of the following steps: (i) confirming the characteristics of the test items fitting the Topic Specific PCK construct, (ii) production of test items, (iii) judgment of items, (iv) construction of the instrument (v) piloting and (vi) validation of the instrument. Care is taken to ensure presentation of multiple evidence and discussions, addressing the interpretive and arguments as requirements for showing validity of the construct measured by the instrument. The Topic Specific PCK tool is validated with a group of 20 practicing teachers. The tool is scored, using a rubric corresponding to the five components with each being rated on a four point scale, from 1 (Limited) to 4 (Exemplary). The analysis of the generated scores is done using the Rasch statistical model (Winstep, version 3.72.3). The reliability indices as indicated by person reliability and item reliability are found to be high at 0.86 at 0.91, respectively. The persons and item scores reflect measures well inside the conventionally acceptable range of -2 and +2. A further indicator of validity of the tool is the empirically calculated hierarchy of test items’ order of difficulty, found similar to the theoretically predicted pattern for the teacher group. Based on the above analysis and findings, I regard the tool as valid and reliable. My research design is based on mixed-methods research (MM). The research strategy takes the form of a case study. The study is located in a methodology class for final year physical science pre-service teachers. They formed an experimental group (N=16) for this study. I delivered an intervention, targeting understanding of transformation of Chemical Equilibrium concepts, using the above listed five knowledge components. I collected data through a combination of tools, including the newly designed Topic Specific PCK tool in Chemical Equilibrium, an Achievement tool and a science teacher Belief tool. Both the Achievement and the Belief tools were adapted from existing tools, and were thus considered tried and validated. The findings suggest that the quality of Topic Specific PCK in chemical equilibrium may be improved in pre-service teachers by the explicit discussion of the knowledge enabling its transformation. They also suggest that, in the process of discussing aspects of subject matter knowledge related to its transformation, pre-service teachers improve their conceptual understanding of chemical equilibrium. Both these improvements were not affected by the shift or lack of shift in teacher beliefs from teacher-centred towards student-centred practices. I acknowledge the small size of the sample as a practical limitation to the generalization of the statistical findings in this study. I suggest that emphasis be placed on the trends displayed, as they are similar to those obtained from the multiple sources of the qualitative component of the study. Finally, I recommend that the development of PCK in pre-service teachers be considered in a topic by topic manner. I urge that the teaching of chemistry topics be explicitly organized in a format in which pre-service teachers would be expected to reason about them, and particularly transform them for teaching.