Abstract: Employee #1 was performing a test procedure to determine the chlorine number for pentachloronitrobenzene (pcnb). Part of the procedure is to heat the mixture to 50 degrees C. Using a pipet, Employee #1 added 50 ml of distilled water. This procedure was performed in a lab hood with the door half open. When she added the water, an exothermic reaction occurred; the mixture started to boil. When she saw the mixture boiling violently, Employee #1 stepped back. The mixture exploded, and part of the chemical splashed and hit the inside lab door. The rest splashed on the floor and a few drops hit Employee #1 on the face. Employee #1 was hospitalized with chemical burns. Management stated it was an "anomaly" mixture.