After a series of tragic accidents related to the “rainbow experiment” in high school chemistry labs, the United States Chemical Safety Board (CSB) took the unprecedented step of releasing a video safety message to warn educators about the dangers of the procedure.
The experiment in question is a flame test, a procedure where metal salts are analyzed by the different color flames they produce. By heating the substances with a flame, the electrons of the metal ions become excited and emit visible light (see our module Atomic Theory II for more information on the connection between heat and light). In the rainbow experiment particular substances are chosen because they emit a vivid array of colors, hence the “rainbow” name.
Over the past decade the rainbow experiment has resulted in several teachers and students being severely burned, mainly due to the use of methanol – a very flammable solvent – as an accelerant. The most recent accident occurred in January at a Manhattan high school, where two students watching the experiment were surrounded by flames and one suffered severe burns.
So if this experiment is dangerous and has a record of accidents associated with it, why is it still being performed? The American Chemical Society (ACS) helps to answer this question: the experiment “offers the ‘wow’ factor that interests and delights students.” Since it is very dramatic and offers instant visual evidence of the underlying chemical processes, the rainbow experiment is a memorable demonstration. But the ACS also notes that there should also be “a ‘whoa’ factor of very significant risk to students and teachers” when performing this experiment. In this case, the “whoa” should clearly outweigh the “wow” element. ACS has issued guidelines for an improved rainbow flame test that removes the methanol accelerant and improves the safety of participants.
Since science is a process of discovery, school science labs mimic that exploration through controlled experiments and procedures (see our Experimentation in Scientific Research module). But just like scientists working in the field, students and teachers in the science lab have to carefully follow safety protocols to prevent accidents. Though not frequent, accidents in school science labs do occur. A common denominator in most of these accidents is a failure to follow common safety protocols, such as not wearing protective gear or using accelerants near open flames.
As Calais Weber, a rainbow experiment accident survivor, states in the CSB video, everyone has a responsibility to ensure safety in the chemistry lab. Instructors must lead by example in using appropriate protective equipment, setting up chemical handling procedures, and enforcing safety practices. Students must also be involved by reading the safety protocols, following instructions step-by-step, and asking questions if they feel unsafe. By working together, everyone in the chemistry lab can promote an environment of safety and accident prevention.
– The National Science Teachers Association has a collection of resources about Safety in the Science Classroom, including booklets and handouts.
– American Chemistry Society provides a series of policy recommendation for promoting chemistry safety in the classroom.
– The Centers for Disease Control publishes the School Chemistry Laboratory Safety Guide on their website.
Written by Eric Dillalogue
Eric Dillalogue holds a MS in Library and Information Science and a BA in English. He has worked in a variety of roles from service industry management, academic libraries, and grant administration. He has taught courses on information literacy, web research, and developmental reading. Eric joined the Visionlearning team as a project manager in 2014.