The Decomposition of Zinc Carbonate: Using Stoichiometry To Choose between Chemical Formulas

Stephen DeMeo
Department of Curriculum and Instruction, Department of Chemistry, Hunter College of the City University of New York, New York, NY 10021
J. Chem. Educ., 2004, 81 (1), p 119
DOI: 10.1021/ed081p119
Publication Date (Web): January 1, 2004
History, Education, and Documentation

Abstract

The decomposition of zinc carbonate is an activity for introductory chemistry students that involves determining the correct chemical formula from two choices described in popular texts. The formula for zinc carbonate in The Merck Index is listed as 3Zn(OH)2•2ZnCO3, while the Aldrich Catalogue expresses zinc carbonate as a hydrate, ZnCO3•2Zn(OH)2•xH2O. This difference in formula is important pedagogically since it creates a problem for students to solve. To determine which formula corresponds to a bottle labeled "zinc carbonate", students perform qualitative tests on three of zinc carbonate's decomposition products: zinc oxide, carbon dioxide, and water. Next students make quantitative measurements to find molar ratios and compare them with the coefficients of the balanced chemical equations. This allows the correct formula of zinc carbonate to be deduced. Students utilize stoichiometry, barometric pressure calculations, the ideal gas law, and a variety of chemical techniques, such as the collection of a gas over water, to solve this problem.

Keywords (Audience):

High School / Introductory Chemistry

Keywords (Domain):

Laboratory Instruction

Keywords (Pedagogy):

Inquiry-Based / Discovery Learning

Keywords (Subject):

Gases
View: Hi-Res PDF | PDF w/ Links

Citing Articles

View all 3 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 3 ACS Journal articles (3 most recent appear below).

Tools

SciFinder Links

SciFinder subscribers: Click to sign in | Not a SciFinder subscriber? Learn more at www.cas.org

Explore by:

History

  • Received: August 03, 2009

Recommend & Share

  • Share on ACS NetworkACS Network
  • Add to FacebookFacebook
  • Tweet ThisTweet This
  • Add to CiteULikeCiteULike
  • Add to NewsvineNewsvine
  • Digg ThisDigg This
  • Add to DeliciousDelicious

Related Content