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Title: A guided-inquiry learning unit on the Dushman reaction for determining Iodate in salt
Authors: Bhinyo Panijpan
Keywords: Dushman reaction;Lodate;Salt
Issue Date: 2011
Publisher: Srinakharinwirot University
Citation: Journal of Srinakharinwirot University (Science and Technology). 3, special 1 (Jan. 2011), 327-331
Abstract: Iodine is an element critical for normal functioning of the thyroid gland, a key regulator of the body’s basic metabolic rate. A lack of iodine during infancy may cause a condition known as cretinism in which mental and physical development is severely impaired. Adults need about 150 micrograms of iodine in the form of iodide ion per day. A guided-inquiry laboratory was designed for 27 grade-10 students who determined the amount of iodate in various iodized salt and sea salt by using the Dushman reaction involving iodate and iodide in the presence of acid to give iodine which reacts with partially soluble starch present in the reagent blue starch-iodine complex. The different intensities of the blue color reflected different concentrations of iodate. Not only did students learn how to determine the amount of iodate in salt but also learned how to work with the spectrophotometer using Beer’s law. Collections of students’ learning data included parallel pretest and posttest, a questionnaire, laboratory report, and interview. Students showed gains in conceptual understanding of the chemical reaction between iodate and iodide for the determination of iodate in salt. They also expressed positive attitude toward the guided-inquiry learning unit which gave them the opportunity to do the experiment with a spectrophotometer.
ISSN: 1686-9311
Appears in Collections:MU: National Journal Publications

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