Phosphorus oxychloride (POCl₃) is a volatile chemical molecule with a "fiery temper"-it absolutely loathes acidic environments. Upon contact with strong acids (such as hydrochloric or sulfuric acid), it immediately decomposes to produce toxic hydrogen chloride gas and phosphoric acid. This reaction is violent and exothermic; it is akin to dropping an ice cube into a pan of hot oil-causing not only smoke but also potential splattering.

Structural instability: The phosphorus atom is already under strain from holding onto three chlorine atoms, and hydrogen ions from the acid snatch the chlorine atoms away.

Chain reaction: The generated hydrogen chloride turns into hydrochloric acid upon contact with moisture, further accelerating the decomposition process.

Heat feedback: The heat released by the reaction causes the decomposition rate to increase rapidly.

Interestingly, while weak acids (such as acetic acid) have a less immediate impact, prolonged exposure will still lead to gradual degradation.

Store away from all acidic substances; recommendations include:

Seal in glass bottles and keep away from cabinets containing acidic reagents.

Wear a gas mask and acid-resistant gloves during handling.

In the event of a leak, neutralize first with a base (such as sodium carbonate) before rinsing with water.