|
|
| Home > JCE Print > Journal of Chemical Education > Issues >
2004
>
January
> |
|
In the Laboratory
|
|
|
|
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
|
|
January 2004
Vol. 81 No. 1
p. 119
|
|
|
|
|
|
|
| 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.
|
| Supplement |
Student procedures, instructions for qualitative tests, and a postlab check list; instructor notes, which include sample measurements, calculations, and results; and an equipment list, a diagram of the experimental setup, and chemical preparations are available.
|
 Contents |
JCE2004p0119W.doc (Microsoft Word)
|
| Download |
|
|
| More Information |
Citation |
DeMeo, Stephen. J. Chem. Educ. 2004 81 119.
|
Keywords |
Gases; General Chemistry; Inquiry-Based / Discovery Method; Introductory / High School Chemistry; Laboratory Instruction; Stoichiometry; Zinc
|
History |
Created:
Last Updated: |
December 8, 2003
February 18, 2005
|
|
|
|
|
|
| Home > JCE Print > Journal of Chemical Education > Issues >
2004
>
January
> Page
119
|
|
|
| JCE HS CLIC |
|
Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
|
| Contributions Welcome |
| JCE welcomes your submission |
| Advertisers |
| In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first. |
| Be An Ambassador |
| Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants. |
|
