Synthesis and Decomposition of Zinc Iodide: Model Reactions for Investigating Chemical Change in the Introductory Laboratory

Stephen DeMeo
Barnard College, Columbia University, New York, NY 10027
J. Chem. Educ., 1995, 72 (9), p 836
DOI: 10.1021/ed072p836
Publication Date: September 1995

Abstract

The purpose of this article is to discuss two colorful reactions not widely used by chemical educators in high schools or college chemistry laboratories: The synthesis of zinc iodide from its elements, zinc and iodine, and the subsequent decomposition of zinc iodide back into its elements. These reactions are important for chemistry teachers to know about because they can be performed by introductory students to understand different aspects of chemical change such as the concepts of reaction, compound, bonding, excess and limiting reactants, an empirical formula, balanced chemical equation, the conservation of matter and energy, the Law of the Conservation of Mass, and the Law of Constant Composition. These concepts, in turn, are important because they are fundamental to chemistry, are widely taught by chemistry teachers, and are deceptively difficult for introductory chemistry students to understand.The synthesis of zinc iodide has many scientific advantages over current syntheses of binary compounds from elements such as the syntheses of copper sulfide and magnesium oxide. For example, zinc iodide can be synthesized to 1% of theoretical mass in less than a half an hour and can be readily analyzed qualitatively as well as quantitatively by two different titrations. As a set of reactions, the synthesis and decomposition of zinc iodide is safe to perform, reliable, inexpensive, and does not pose a threat to the environment.

The author has developed a small collection of teacher activities describing the synthesis and decomposition of zinc iodide. The activities are innovative because they contain improvements not found in the existing literature. Appropriate for high school and first year college chemistry teachers, all of the activities contain detailed procedures and discussions as well as safety and disposal requirements.

Keywords (Audience):

High School / Introductory Chemistry

Keywords (Domain):

Laboratory Instruction

Keywords (Pedagogy):

Hands-On Learning / Manipulatives

Keywords (Subject):

Synthesis

Citing Articles

Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder.

This article has been cited by 6 ACS Journal articles (5 most recent appear below).

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    How Do New Teachers Choose New Labs?

    Stephen DeMeo
    Journal of Chemical Education2007 84 (10), 1702
    • How Do New Teachers Choose New Labs?

      Stephen DeMeo
      Journal of Chemical Education2007 84 (10), 1702

      Forty-eight new secondary science teachers participated in a study that required a listing, discussion, and application of criteria to rank three chemistry laboratory procedures. The three similar lab procedures involved synthesis of a compound from its ...

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    Teaching Lab Report Writing through Inquiry: A Green Chemistry Stoichiometry Experiment for General Chemistry

    Kristen L. Cacciatore , Hannah Sevian
    Journal of Chemical Education2006 83 (7), 1039
    • Teaching Lab Report Writing through Inquiry: A Green Chemistry Stoichiometry Experiment for General Chemistry

      Kristen L. Cacciatore , Hannah Sevian
      Journal of Chemical Education2006 83 (7), 1039

      We present an alternative to a traditional first-year chemistry laboratory experiment. This experiment has four key features: students utilize stoichiometry, learn and apply principles of green chemistry, engage in authentic scientific inquiry, and ...

  • Cover Image

    Mass Relationships in a Chemical Reaction: Incorporating Additional Graphing Exercises into the Introductory Chemistry Laboratory

    Stephen DeMeo
    Journal of Chemical Education2005 82 (8), 1219
    • Mass Relationships in a Chemical Reaction: Incorporating Additional Graphing Exercises into the Introductory Chemistry Laboratory

      Stephen DeMeo
      Journal of Chemical Education2005 82 (8), 1219

      The purpose of this article is to increase student involvement with graph construction specifically in the context of introductory laboratory activities that involve mass relationships between reacting substances and products. In this regard, five mass–...

  • Cover Image

    Synthesis of Zinc Iodide Revisited

    Stephen DeMeo
    Journal of Chemical Education2003 80 (7), 796
    • Synthesis of Zinc Iodide Revisited

      Stephen DeMeo
      Journal of Chemical Education2003 80 (7), 796

      Two inquiry-based labs that complement a previously published activity in this Journal, "The Synthesis and Decomposition of Zinc Iodide: Model Reactions for Investigating Chemical Change in the Introductory Laboratory", are described. These two ...

  • Cover Image

    Making Assumptions Explicit: How the Law of Conservation of Matter Can Explain Empirical Formula Problems

    Stephen DeMeo
    Journal of Chemical Education2001 78 (8), 1050
    • Making Assumptions Explicit: How the Law of Conservation of Matter Can Explain Empirical Formula Problems

      Stephen DeMeo
      Journal of Chemical Education2001 78 (8), 1050

      The law of conservation of matter plays an important part in the story of the determination of the empirical formula of a compound. Utilizing the law of conservation could promote student understanding of this subject by providing the rationale for many ...

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  • Received: August 03, 2009

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