Beyond Benign

Lead Teacher Blog

Javner, Cassidy

Why replacement labs?

Open flames and ‘out of control’ chemistry are not tolerated in industry, but there are still quite a few accidents as a result of these practices in the high school setting. As a high school teacher it is important to find safe, sustainable alternatives to some of the traditional, hazardous, and sometimes dangerous chemistry labs. Replacement labs are labs that teach the same concepts, skills, and knowledge but use equipment and chemicals that are safe for our students and the environment. If we can teach the same exact kinetics concepts using starch and Vitamin C, then why not! Often times replacement labs involve materials that can be found at any drugstore or grocery store which makes materials easy to acquire and familiar for students. Furthermore, it can be very powerful to discuss with students why you made the choice to switch to a more sustainable lab. The Beyond Benign website has many different replacement lab options for you to try and Lead Teachers are hard at work to make these labs applicable for your classroom.

The first replacement lab that I used in my Honors Chemistry classroom was the Le Chatelier’s Principle Lab, which replaced the traditional cobalt complex lab. According to the SDS, the cobalt compounds involved in the traditional lab are possible carcinogens and moderately toxic by ingestion and strict personal protective equipment is required when using this compound. The replacement lab has two equilibrium systems that students analyze:

Black Tea – H+ Complex
● In this example, lemon juice (or vinegar) is used to increase the acidity of the solution and household ammonia is used to increase the basicity of the solution.

Starch- Iodine Complex
● In this example, a complex is first created using starch and tincture of iodine and then the temperature is increased and decreased.

Through these examples students were able to see how temperature and concentration affects the shifting of an equilibrium system, all while using non-toxic, household products! This lab removes hazards for both students and teachers (minimizes hazardous waste disposal), yet still allows students to analyze color changes in equilibrium systems. Check out the Le Chatelier’s Principle Lab and the accompanying short video demonstration here.

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