The Synthesis and Analysis of Copper(I) Iodide: A First-Year Laboratory Project

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A general chemistry laboratory project involving the synthesis and analysis of copper(I) iodide is described. The copper(I) iodide can be prepared by either direct reaction of the elements in toluene or reaction of iodide with a copper(II) salt. Characterization of this lower-oxidation-state iodide of copper is accomplished by determination of copper by precipitation and weighing of cupric oxide, and by determination of iodine by oxidation to I2, collection by sublimation, and weighing. Typical student work gives results for copper and iodine within about 1 and 3%, respectively, of the theoretical. The project provides a convenient preparation of a compound whose identity will not be obvious to students. The analytical procedures illustrate the fundamentals of gravimetric analysis and some basic chemical and physical characteristics of the elements. The analytical data allow students to find the identity of the product by determining its empirical formula. Rationalization of the stability of CuI should involve discussions of relative insolubilities and Ksp, the hard/soft acid-base principle, stoichiometry, and, of course, the redox chemistry of copper and the halogens. Students can also explore the relative advantages of the two methods of preparation and compare the purity of the products.


Originally published as:

Margolis, L. A., Schaeffer, R. W., & Yoder, C. H. (2001). The synthesis and analysis of copper(I) iodide. A first-year laboratory project. Journal of Chemical Education, 78(2), 235. https://doi.org/10.1021/ed078p235