Lesson Learned from a Fire during Distillation: Choose the Appropriate Condenser

A fire broke out during the distillation of carbon disulfide (CS2). The increasing pressure inside the three-necked flask pushed a stopper open, and the emitted CS2 subsequently ignited. Fortunately, the fire was put out soon, and no one was injured. In this work, we describe the direct and underlying causes of the incident as well as the subsequent safety conversation about the incident in our massive open online course (MOOC), Safety in the Chemical Laboratory. While the students identified many contributing causes of the incident, none questioned the risk assessment of the experimental setup. Therefore, we provide fundamental information to aid both our students and other researchers in their selection of the most appropriate condenser for their redistillation or reflux conditions.