Typically the first lab in general chemistry involves measurements of physical properties. The lab reviews proper techniques for the balance and measuring volumes in graduated cylinders. While the principle can be demonstrated with any chemicals, we chose to use less hazardous materials to demonstrate the first principle of green chemistry, prevention of hazardous waste.
This lab exercise is a demonstration of a familiar reaction, the formation of carbon dioxide from baking soda mixed with a weak acid. The exercise gives students an opportunity to measure density and predict how it will affect the rate of a reaction. The students can compare the extrinsic and intrinsic properties of compounds and visualize the relative density of the reactants. With the addition of food coloring, the components are to visualize and the demonstration is easy to reproduce in their notebook.
This laboratory exercise can be completed in a 1-2 hour period and helps students develop good technique in weighing out reagents and enables them to practice dimensional analysis and density calculations. In addition students are introduced to chemical formulas and balancing acid-base reactions.
The link to the laboratory procedures includes data tables and pre-lab and post-lab questions for a college General Chemistry course.
Summary prepared March 2012 by Jessica Kaufman, Assistant Professor of Biology/Biotechnology at Endicott College.
van Kirk, K.; Kaufman, J. D. Lava Lamp Density Demonstration, Biology/Biotechnology, Endicott College, 2012