Determination of the Formula of a Hydrate: A Greener Alternative

Author Contact: mklin2@uis.edu

Summary

The determination of the formula of a hydrate is an experiment that introduces students to many fundamental chemical concepts including stoichiometry, the notion of a mole and nomenclature. In this experiment the authors replace the previously used calcium and barium salts because the latter is considered poisonous and a tumorigen and both were where considered waste after only one use. Instead, copper salts are being used because they are less toxic, less expensive, recyclable and produce vivid color changes (blue to brown) during the experiment. Not only are students exposed to the concept of environmentally responsible chemistry, but are asked to determine the formula of a copper chloride hydrate salt by measuring the change in mass after water is evaporated from the sample. The lab is also made safer by dehydrating the copper salt using an oven instead of individual Bunsen burners.

Supplemental information includes a materials list, pre and post-lab questions, an introduction and laboratory procedures.

Summary prepared January 2009 by Douglas M. Young at the University of Oregon.

Category Descriptors

Chemistry Concepts

• Gravimetric Analysis (Measurement/Analysis)
• Stoichiometry

Laboratory Techniques

• Assembly of Reaction Apparatus
• Heating and Cooling Methods
• Measuring Mass and Volume

Green Chemistry Principles

• Design Less Hazardous Chemical Syntheses
• Minimize the Potential for Accidents
• Prevent Waste
• Use Safer Solvents/Reaction Conditions

Chemistry Subdiscipline

• Inorganic Chemistry

Target Audience

• Colleges/Universities
• Secondary Schools

Source

• Journal Articles