Driving Sustainability in CU Boulder’s General Chemistry Teaching Labs | Environmental Center

Did you know that thousands of students pass through CU Boulder’s General Chemistry Teaching Labs every semester? As a result, small actions for efficiency by each student adds up to large impacts. The staff of the CU Boulder General Chemistry Teaching Lab Program have been paying attention to find and implement modifications for sustainability in the teaching labs.  

We sat down to speak with Estrella Lastre, Lab Coordinator II in the Department of Chemistry, to learn about the sustainability geared changes that have been made. Lastre explains that, “We get to see these experiments happen hundreds of times each semester, and taking time to observe those larger patterns matters when you’re trying to reduce waste.” Lab Coordinators for the General Chemistry Teaching Labs complete safety checks during each lab period. Completing a brief walk through over 100 lab sections each week provides a macro view of the program – helping Lastre and her team identify what adaptations or changes can be made without lessening the students’ learning experience. Lastre attributes being physically present in the lab space as a key part of how their team has found opportunities to reduce waste. They are seeing first hand what excess materials are being disposed of during each period, or when the trash cans or hazardous waste in lab rooms are filling up quickly with a particular item.

By applying a practical approach to obtaining increased sustainability, the CU Boulder General Chemistry Teaching Labs have been able to implement numerous actions leading to more efficient use of materials. 

• Re-usable in-lab manuals reduce paper use by 90%: Instead of 2000 students per semester purchasing individual lab manuals, the teaching labs provide in-lab copies and online manuals for students to use.  Beyond the paper savings, this effort is saving students money and increasing safety by reducing the likelihood that students bring home contaminated materials with them.
• Re-use of foam cups reduces foam waste by more than 80%: During the Mole Ratios experiment in CHEM 1401/CHEM 1114, instead of each lab section getting a new set of foam cups, the cups are re-used between sections.  As a result, in Spring 2025 only 60 styrofoam cups were needed between 38 lab sections instead of 380 cups.
• Micro-titration set-up significantly reduces chemical use: Instead of each pair of students using hundreds of milliliters of chemicals in the Titration Experiment in CHEM 1134, a switch from an average full-scale titration set-up to a micro-titration procedure reduces chemical uses to only drops per student pair, greatly reducing hazardous waste generation.
• Re-use of centrifuge tubes reduces plastic waste by more than 90%: Instead of plastic centrifuge tubes being handled as single-use items by students running a 3-week experiment in CHEM 1134 and 2101, students are taught how to safely clean and re-use tubes across sections of the courses. Without this shift, the experiment could use upwards of 18,000 centrifuge tubes per semester, and instead only ~1,000 tubes are necessary.  
• Labeling with “re-use” saves materials in labs: In multiple instances, the teaching lab staff have begun to write “re-use” to communicate to students items that can be re-used over and over again such as sandpaper used in CHEM 1401, CHEM 1114, and CHEM 1021.  In another example, instead of 50 plastic weigh boats historically being used per lab section during a CHEM 1021 experiment, it was determined that, with minor modifications, the boats could safely be reused for that particular experiment, reducing boat plastic waste by 90%. 

What more to look for:  Lastre shared how over the course of the next few semesters, new solutions will continue to be implemented to enhance sustainability and learning. For example, one change that has been launched during Fall 2025 is transitioning to digital pre-lab quizzes to eliminate the need for each student to submit a paper copy in-person – amounting to well over 20,000 sheets of paper saved each semester!

The Department of Chemistry has been taking action for sustainability and green chemistry for more than 10 years. Ongoing efforts within the department’s teaching labs are a reflection of the importance of green chemistry education at CU Boulder and aligns with CU Boulder’s vision to “transform lives in service to a just and sustainable world.”