scope:

Description of Driving Event:

A tightly capped bottle containing dilute aqua regia chemical waste was stored in a fume hood. Evolved gases resulted in a pressure build-up causing the bottle to explode. The contents sprayed across the room onto the floor. The bottle explosion occurred overnight when the laboratory was unoccupied; however, a potential acid burn exists if an employee was in the room at the time of the bottle explosion.

A review of available literature indicates that aqua regia, which is a combination of hydrochloric acid and nitric acid, will oxidize with time resulting in the evolution of Nitrous Oxide (NO2). This reaction is ongoing and is subsequent to the intended use of the mixture. This pressure build-up is normal for this type of mixture.