In this Activity, students use supermarket chemicals to test samples of table salt for the presence of iodine, an essential micronutrient added as iodide ion. The presence of iodide in the salt is made apparent by the appearance of a blue color. This Activity can introduce the subject of micronutrients, in terms of their importance and how they may be supplied to a population to prevent disease. It can also be used in a discussion of redox chemistry or the descriptive chemistry of iodine, particularly the facile oxidation of iodide to iodine and the formation of the blue starch-iodine complex.
Stephen W. Wright, J. Chem. Educ. 2007, 84, p1616A.