In the Laboratory
Classroom Activity Extension
Make a Match! by Erica K. Jacobsen
Sucrose Laboratory #1, JCE Classroom Activity #97
Sucrose Laboratory #2
The Sweeter Side of Density by Michael Davis and Charles Henry, J. Chem. Educ. 2008, 85, 1088A–1088B.
Measuring the Density of a Sugar Solution: A General Chemistry Experiment Using a Student-Prepared Unknown by Karen I. Peterson, J. Chem. Educ. 2008, 85, 1089–1090.
Students determine the density of different sugar solutions. They then dye the solutions and devise a method to combine these miscible solutions to form a multi-colored, layered heterogeneous mixture. Afterward, they predict what the color and density of the layered solutions will be after mixing, then they mix, observe, and measure.
Students prepare a sucrose solution with an instructor-assigned concentration. They calibrate a graduated cylinder with water, and determine the density of the solution multiple times. Students determine possible sources of error and are graded on accurate and precise results.
Create Your Own Combination The experiments described above both appear in this month’s issue of JCE, and nicely complement one another. Why not use Davis and Henry’s activity to first teach students how to determine a solution’s density, and extend it by using Peterson’s experiment to have students predict the density of a solution with a concentration partway between the concentration of two solutions previously used in the activity? Then, students can prepare the solution themselves and measure the density. Or, flip flop the two. Students could first perform Peterson’s laboratory procedure in order to help prepare different solutions for use in the Davis and Henry activity, while discussing possible sources of error in density measurements that they may come across in the activity. What would work in your classroom?
Supporting JCE Online Material
http://www.jce.divched.org/Journal/Issues/2008/Aug/abs1090.html Full text (PDF) with links to cited JCE articles
1090
Journal of Chemical Education • Vol. 85 No. 8 August 2008 • www.JCE.DivCHED.org • © Division of Chemical Education
