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Showing 16 to 30 of 92 results Save | Export
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Wang, Jessie J.; Nun´ez, Jose´ R. Rodríguez; Maxwell, E. Jane; Algar, W. Russ – Journal of Chemical Education, 2016
A guided-inquiry project designed to teach students the basics of spectrophotometric instrumentation at the second year level is presented. Students design, build, program, and test their own single-wavelength, submersible photometer using low-cost light-emitting diodes (LEDs) and inexpensive household items. A series of structured prelaboratory…
Descriptors: Science Instruction, Undergraduate Study, College Science, Science Laboratories
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Cao, Tingting; Zhang, Qing; Thompson, Jonathan E. – Journal of Chemical Education, 2015
A syringe-based, electronic fluid dispenser is described. The device mechanically connects a syringe plunger to a linear slide potentiometer. As the syringe plunger moves, the electrical resistance between terminals of the potentiometer varies. Application and subsequent measurement of a DC voltage between the potentiometer pins is used to track…
Descriptors: Science Instruction, Science Laboratories, Laboratory Equipment, Chemistry
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Journal of Chemical Education, 2015
This paper presents the design and practical application of a laboratory inquiry at high school chemistry level for systematic chemistry learning, as exemplified by a thermochemical approach to the reaction stoichiometry of neutralization using Job's method of continuous variation. In the laboratory inquiry, students are requested to propose the…
Descriptors: Secondary School Science, Science Instruction, Inquiry, Active Learning
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Okanlawon, Ayoade Ejiwale – African Journal of Research in Mathematics, Science and Technology Education, 2012
Using constructivist theory and knowledge components as a theoretical framework, this paper reports lecturers' perceptions of prior knowledge needed for solving a sample acid-base titration problem involving the neutralization of a conjugate base of a weak acid with a strong acid. Twelve participants were engaged for the study. Their participation…
Descriptors: Chemistry, Teacher Attitudes, Barriers, Success
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Garvey, Sarah L.; Shahmohammadi, Golbon; McLain, Derek R.; Dietz, Mark L. – Journal of Chemical Education, 2015
A laboratory experiment is described in which students compare two methods for the determination of the calcium content of commercial dietary supplement tablets. In a two-week sequence, the sample tablets are first analyzed via complexometric titration with ethylenediaminetetraacetic acid and then, following ion exchange of the calcium ion present…
Descriptors: Dietetics, Comparative Analysis, Statistical Analysis, Laboratory Experiments
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Celeste, M.; Azevedo, C.; Cavaleiro, Ana M. V. – Journal of Chemical Education, 2012
A laboratory experiment based on the titration of boric acid with strong base in the presence of d-mannitol is described. Boric acid is a very weak acid and direct titration with NaOH is not possible. An auxiliary reagent that contributes to the release of protons in a known stoichiometry facilitates the acid-base titration. Students obtain the…
Descriptors: Chemistry, Laboratory Experiments, Science Instruction, Science Laboratories
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Miranda, Breanna; Lawton, Nicole M.; Tachibana, Sean R.; Swartz, Natasja A.; Hall, W. Paige – Journal of Chemical Education, 2016
Quantification of the many constituents that make up our food, whether they are desirable (vitamins, antioxidants, nutrients) or undesirable (pesticides, toxins), is one of the most practical applications of chemistry. In this study, kombucha, a popular fermented tea beverage, was analyzed using acid-base titration and high-performance liquid…
Descriptors: Chemistry, Science Education, Science Instruction, Laboratory Experiments
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Volmer, Dietrich A.; Curbani, Luana; Parker, Timothy A.; Garcia, Jennifer; Schultz, Linda D.; Borges, Endler Marcel – Journal of Chemical Education, 2017
This experiment describes a simple protocol for teaching acid-base titrations using potentiometry, conductivity, and/or photometry to determine end points without an added indicator. The chosen example examines the titratable acidity of a red wine with NaOH. Wines contain anthocyanins, the colors of which change with pH. Importantly, at the…
Descriptors: Biotechnology, Teaching Methods, Food, Chemistry
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Michalowski, Tadeusz; Asuero, Agustin G.; Wybraniec, Slawomir – Journal of Chemical Education, 2013
The final step of the Kjeldahl method of nitrogen determination in biological and other samples faces a dilemma: which titrant, whether acid or base, should be used for the titration of ammonia? To solve this problem, a simple calculation procedure, illustrating the manner of ammonia determination in this method, enables one to resolve this…
Descriptors: Science Instruction, College Science, Computation, Computer Assisted Instruction
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Wadso, Lars; Li, Yujing; Li, Xi – Journal of Chemical Education, 2011
Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a…
Descriptors: Chemistry, Science Laboratories, Heat, Science Instruction
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Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines – Journal of Chemical Education, 2011
A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…
Descriptors: Kinetics, Chemistry, Scientific Methodology, College Science
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Brunori, Maurizio – Biochemistry and Molecular Biology Education, 2012
Before the outbreak of World War II, Jeffries Wyman postulated that the "Bohr effect" in hemoglobin demanded the oxygen linked dissociation of the imidazole of two histidines of the polypeptide. This proposal emerged from a rigorous analysis of the acid-base titration curves of oxy- and deoxy-hemoglobin, at a time when the information on the…
Descriptors: Science History, Biochemistry, Physiology, Molecular Biology
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Caraballo, Rolando M.; Saleh Medina, Leila M.; Gomez, Sergio G. J.; Vensaus, Priscila; Hamer, Mariana – Journal of Chemical Education, 2021
An experimental approach to chemistry is a more meaningful way to learn than the use of textbooks alone. Working in the laboratory helps students understand basic concepts through their active engagement. Here, we present a series of inexpensive and environmentally friendly laboratory exercises on acid-base equilibrium. Their difficulty level is…
Descriptors: Science Instruction, COVID-19, Pandemics, School Closing
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Vieira, Carlos A.; de Paiva, Sabina A. A.; Funai, Milena N. S.; Bergamaschi, Mateus M.; Queiroz, Regina H. C.; Giglio, Jose R. – Biochemistry and Molecular Biology Education, 2010
The main objective of this experiment is to determine the amount of nicotine in commercial brand cigarettes by means of a nonaqueous acid-base titration. A simple glass device simulating a smoker is proposed, which allows the determination of the volatilized, filter retained, and inhaled portions. Students will readily see that the amount of…
Descriptors: Chemistry, Smoking, Science Experiments, Science Instruction
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Fabre, Paul-Louis; Reynes, Olivier – Journal of Chemical Education, 2010
In this experiment, the concentrations of copper and zinc in brass are obtained by two methods. This experiment does not require advanced instrumentation, uses inexpensive chemicals, and can be easily carried out during a 3-h upper-level undergraduate laboratory. Pedagogically, the basic concepts of analytical chemistry in solutions, such as pH,…
Descriptors: Science Instruction, Scientific Concepts, Science Laboratories, Science Experiments
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