Experiments In Chemistry
Mostrando 13-24 de 150 artigos, teses e dissertações.
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13. DETERMINAÇÃO DE Al3+, Fe3+ E Cu2+ PRESENTES EM SOMBRAS DE MAQUIAGEM POR ESPECTROFOTOMETRIA UV-Vis: UMA PROPOSTA DE EXPERIMENTO CONTEXTUAL EM NÍVEL SUPERIOR DE ENSINO
Metallic oxides are used in cosmetic shadows formulations in order to highlight the area around the eyes, with different colors. Due to the close proximity to the eye mucosa, these products are a potential source of metal intoxication in human body. Based in this fact, several analytical methods to quantify metals in cosmetic shadows have been proposed in th
Quím. Nova. Publicado em: 02/05/2019
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14. Isqueiro Pneumático: uma ferramenta versátil ao ensino interdisciplinar
Resumo O isqueiro pneumático é um equipamento que permite produzir fogo por meio de rápida compressão do ar e, quando construído com tubo de acrílico transparente, é possível observar a queima de uma pequena amostra de algodão colocada em seu interior. Por ser um instrumento pouco conhecido e cujo funcionamento chama a atenção vislumbramos seu uso
Rev. Bras. Ensino Fís.. Publicado em: 04/02/2019
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15. Mass Spectrometry Study of Ammonia Formed During Plasma Nitrocarburizing and Nitriding Processes
In this work, we used mass spectrometry to investigate ammonia (NH3) formed during the nitrocarburizing and nitriding processes of α-Fe sintered and low alloy steel by using d.c. glow discharges in different N2/H2/CH4 gas concentration mixtures. Experiments were conducted using two different configurations: one to collect and analyze species probed primaril
Mat. Res.. Publicado em: 16/07/2018
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16. MEASURING THE CONDUCTIVITY OF VERY DILUTE ELECTROLYTE SOLUTIONS, DROP BY DROP
Undergraduate experiments on ionic conductivity are common practice in general chemistry and advanced physical chemistry laboratories. Often, the conductivities are measured for solutions prepared for various salts, in a range of concentrations, and the relationship between solution conductivity and concentration is interpreted in terms of the Kohlrausch law
Quím. Nova. Publicado em: 2018-07
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17. Removal of synthetic sex hormones by hydrothermal carbonization
ABSTRACT One of the most prominent fields of environmental chemistry is the study and the removal of micro-pollutants from aqueous matrices. Analytical techniques for their identification and quantification are becoming more sensitive and comprehensive and, as a result, an increasing number of drugs have been detected in environmental samples. However, the l
An. Acad. Bras. Ciênc.. Publicado em: 14/05/2018
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18. EXTRAÇÃO DO R-(+)-LIMONENO A PARTIR DAS CASCAS DE LARANJA: AVALIAÇÃO E OTIMIZAÇÃO DA VERDURA DOS PROCESSOS DE EXTRAÇÃO TRADICIONAIS
This article reports a study, performed in educational context, to increase the greenness of the extraction of R-(+)-limonene from orange peels. Protocols from the literature were evaluated with the green star (GS)metric and new protocols, based in them, were designed to increase the overall greenness. These were tested in the laboratory and their greenness
Quím. Nova. Publicado em: 2018-03
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19. Natural decomposition of hornbeam wood decayed by the white rot fungus Trametes versicolor
ABSTRACT The impacts of white-rot fungi on altering wood chemistry have been studied mostly in vitro. However, in vivo approaches may enable better assessment of the nature of interactions between saprotrophic fungi and host tree in nature. Hence, decayed and sound wood samples were collected from a naturally infected tree (Carpinus betulus L.). Fruiting bod
An. Acad. Bras. Ciênc.. Publicado em: 07/12/2017
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20. ALÉM DA CAIPIRINHA: CACHAÇA COMO SOLVENTE PARA SÍNTESE ORGÂNICA E EXTRAÇÃO DE PIGMENTO
Cachaça (brazilian sugarcane spirit) was applied for the first time as an alternative solvent in undergraduate experiments of organics synthesis, and natural dye extraction. The classical Claisen-Schmidt condensation of benzaldehyde with acetophenone and with acetone were employed to demonstrate the cachaça viability as solvent. Cachaça was also the recry
Quím. Nova. Publicado em: 2017-10
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21. An Evaluation of the Use of Statistical Procedures in Soil Science
ABSTRACT Experimental statistical procedures used in almost all scientific papers are fundamental for clearer interpretation of the results of experiments conducted in agrarian sciences. However, incorrect use of these procedures can lead the researcher to incorrect or incomplete conclusions. Therefore, the aim of this study was to evaluate the characteristi
Rev. Bras. Ciênc. Solo. Publicado em: 29/08/2016
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22. DESENVOLVIMENTO DE EXPERIMENTO DIDÁTICO DE ELETROGRAVIMETRIA DE BAIXO CUSTO UTILIZANDO PRINCÍPIOS DA QUÍMICA VERDE
In this paper, we describe the development of low-cost teaching experiments of electrogravimetry for undergraduate students using principles of green chemistry. Copper was electrochemically deposited on brass under an electrical current density of 50 mA cm−2 from acidic solutions containing nitrate anions. Color changes at the brass electrode and of the so
Quím. Nova. Publicado em: 2016-01
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23. SÍNTESE DE ÁCIDOS CUMARINO-3-CARBOXÍLICOS E SUA APLICAÇÃO NA SÍNTESE TOTAL DA AIAPINA, CUMARINA E UMBELIFERONA
The synthesis of 3-coumarin-carboxylic acids and their application to the total synthesis of the natural products ayapin, coumarin, and umbeliferone in undergraduate organic chemistry experiments is described herein. The synthetic approach consists of a one-pot cyclization between salyciladehydes and Meldrum's acid in water to produce the above mentioned aci
Quím. Nova. Publicado em: 2015-09
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24. DESENVOLVIMENTO DE FÁRMACOS POR HIBRIDAÇÃO MOLECULAR: UMA AULA PRÁTICA DE QUÍMICA MEDICINAL USANDO COMPRIMIDOS DE PARACETAMOL E SULFADIAZINA E A FERRAMENTA VIRTUAL
SciFinder ®Medicinal Chemistry is a multidisciplinary discipline and the discovery of new bioactive molecules is one of its objectives. Molecular Hybridization (MH) is a strategy of rational design of new prototypes, where the lead compound is produced through an adequate fusion of pharmacophoric sub-unities. Undergraduate laboratory experiments for Medicinal Chemis
Quím. Nova. Publicado em: 2015-07