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- Desafiando o paradigma do ensino da química: o contributo da Universidade Aberta de PortugalPublication . Oliveira, Carla Padrel de; Caetano, Fernando J. P.A Universidade tem, ao longo dos anos, mantido uma enorme capacidade para se transformar e adaptar à evolução do Mundo e esse sentido de mudança é também plasmado na constante procura de novos caminhos, novas ideias e novas soluções. Pretende-se com este artigo apresentar o modelo pedagógico da Universidade Aberta – universidade pública portuguesa de ensino a distância – e em particular a sua aplicação ao ensino da química em contexto de e-learning e no âmbito do curso de 1º ciclo em Ciências do Ambiente. São apresentadas as diferentes estratégias que têm vindo a ser desenvolvidas, nomeadamente o recurso a trabalho experimental, o acesso a laboratórios virtuais e a disponibilização de feedback para as atividades formativas e avaliativas.
- The viscosity of five liquid hydrocarbons at pressures up to 250 MPaPublication . Oliveira, Carla Padrel de; Wakeham, William A.This paper reports new measurements of the viscosity of toluene, n-pentane, n-hexane, n-octane, and n-decane at pressures up to 250 MPa in the temperature range 303 to 348 K. The measurements were performed with a vibrating-wire viscometer and with a relative method of evaluation. Calibration of the instrument was carried out with respect to reference values of the viscosity of the same liquids at their saturation vapour pressure. The viscosity measurements have a precision of _0.1% but the accuracy is limited by that of the calibration data to be +0.5%. The experimental data have been represented by polynomial functions of pressure for the purposes of interpolation. The data are also used as the most precise test yet applied to a representation of the viscosity of liquids based upon hard-sphere theory.
- Mutual diffusivity in n-Heptane + n-Hexane isomersPublication . Lopes, M. L. Matos; Castro, C. A. Nieto de; Oliveira, Carla Padrel deA preliminary study of the effect of branching in the binary diffusion of hexane isomer + n-heptane systems is presented. Measurements have been performed with an instrument modeled for the Taylor dispersion technique, at several compositions, at 297 K, for the n-hexane + n-heptane and 2,2-dimethylbutane + n-heptane binary mixtures. The accuracy is estimated to be 1%. The influence of branching is discussed. It was found that the rough hard sphere model for binary diffusion can reproduce the experimental data within 6%. This model was used to predict the binary diffusion coefficients in the 2-methylpentane + n-heptane and 3-methylpentane + n-heptane mixtures, with an estimated accuracy of 5%.
- New measurements of the viscosity of diisodecyl phthalate using a vibrating wire techniquePublication . Oliveira, Carla Padrel deDiisodecyl phthalate (DIDP) has been proposed as a suitable reference material for industrial application in the region of moderately high viscosity. The paper reports a new set of viscosity measurements of a 99.5 % GC sample of this substance, which are directly traceable to the primary standard reference values the viscosity of water at 293.15 K. The present measurements, performed with a vibrating-wire sensor, were carried out at atmospheric pressure over the temperature range (283 to 313) K. Over this temperature range, the viscosity varies from approximately (37 to 267) mPaâs. The measurements have been carried out with an instrument that has already been the subject of improvement since the first measurements were performed, and it relies upon calibration exclusively against the primary standard of viscometry. The estimated overall uncertainty of the results does not exceed ( 1 %, over the whole range of the measurements and, for the results obtained at temperatures in the vicinity of 293 K, is ( 0.8 %. The higher quality of the present measurements, and their direct traceability to the primary reference value for viscosity, justifies the replacement of our earlier set of preliminary data on DIDP viscosity.
- 2008 Ano Internacional do Planeta Terra: Terra, saúde e alterações climáticasPublication . Amador, Filomena; Oliveira, Carla Padrel de; Cardoso, Abel; Antunes, Ana PaulaAs causas ambientais de alguns problemas de saúde, relação entre alterações climáticas e saúde e as dinâmicas de algumas doenças emergentes no quadro das relações humanas com o meio ambiente. Visita ao Jardim Tropical de Lisboa, com os Professores Carla Oliveira, docente da Universidade Aberta e Jorge Atouguia, médico especialista em Medicina Tropical.
- Ano Internacional da Química 2011: porquê 2011?Publication . Caetano, Fernando J. P.; Oliveira, Carla Padrel de; Oliveira, PauloPor que motivo 2011 foi escolhido para comemorar o Ano Internacional da Química (AIQ). Participação do Professor Jorge Calado, do Departamento de Engenharia Química do Instituto Superior Técnico e Presidente da Comissão Nacional para o AIQ-Ano Internacional da Química 2011.
- The viscosity of R32 and R125 at saturationPublication . Oliveira, Carla Padrel de; Wakeham, William A.This paper reports new measurements of the viscosity of R32 and R125, in both the liquid and the vapor phase, over the temperature range 220 to 343 K near the saturation line. The measurements in both liquid and vapor phases have been carried out with a vibrating-wire viscometer calibrated with respect to standard reference values of viscosity. It is estimated that the uncertainty of the present viscosity data is one of 0.5-1%, being limited partly by the accuracy of the available density data. The experimental data have been represented by polynomial functions of temperature for the purposes of interpolation.
- Química geral : reactividade químicaPublication . Oliveira, Carla Padrel de; Caetano, Fernando J. P.; Antunes, Elisa; Leão, HelenaO vídeo trata as reações de oxiredução e as reações de complexação. São explicados e exemplificados os conceitos de redutor, oxidante, elemento de pilha e pilha eletroquímica.
- Validation of a vibrating-wire viscometer: measurements in the range of 0.5 to 135 mPa'sPublication . Oliveira, Carla Padrel de; Caetano, Fernando J. P.; Fareleira, João M. N. A.; Wakeham, William A.The present article describes a novel vibrating-wire viscometer that has been shown to be able to measure viscosities up to 135 mPaâs, after calibration against water at 20 °C, to provide direct traceability to the primary reference for viscosity. For the purpose of validating the instrument, measurements of the viscosity of some selected fluids, including standard reference liquids with viscosity on the order of 100 mPaâs at 20 °C and 2,2,4-trimethylpentane with a viscosity of about 0.5 mPaâs at the same temperature, were performed. The results obtained show that the instrument is capable of performing viscosity measurements with an estimated overall uncertainty better than (0.8% over the range of (0.5 to 135) mPa's.
- An industrial reference fluid for moderately high viscosityPublication . Oliveira, Carla Padrel de; Caetano, Fernando J. P.; Fareleira, João M. N. A.; Fröba, Andreas P.; Harris, Kenneth R.; Leipertz, Alfred; Trusler, J. P. Martin; Wakeham, William A.In industrial practice, there is a demand for a reference standard for viscosity that is established for a readily available fluid to simplify the calibration of industrial viscometers for moderately high viscosities [(50 to 125) mPa · s]. Diisodecyl phthalate (DIDP) has been suggested as that reference fluid, and a number of studies of its properties have been carried out in several laboratories throughout the world, within the auspices of a project coordinated by the International Association for Transport Properties. That project has now progressed to the point where it is possible to collate the results of studies of the viscosity of the fluid by a number of different techniques, so as to lead to a proposed standard reference value which will be included in the paper. To support this recommended value, the various measurements conducted have been critically reviewed, and the sample purity and other factors affecting the viscosity have been studied. Density and surface tension measurements have also been performed. This paper does not describe the individual viscosity determinations carried out in independent laboratories because these are the subject of individual publications, but it does describe the ancillary studies conducted and their relevance to the viscosity standard. In addition, the paper contains recommended values for the viscosity of liquid DIDP. The samples of DIDP to which the recommended values refer are isomeric mixtures available commercially from certain suppliers, with a minimum purity by gas chromatography of 99.8 %. The recommended values result from a critical examination of all the measurements conducted to date and are supported by careful arguments dealing with the likely effects of the isomeric content of the sample as well as of other impurities. The proposed reference standard is intended particularly to serve an industrial need for a readily available calibration material with a viscosity close to that required in practical situations. To that end, the recommended value has an overall relative uncertainty of approximately 1 %. It is therefore not intended to supersede for the reference value for the viscosity of water at 20 °C, which is known much more accurately, but rather to complement it.