Chlorine trifluoride is a colorless gas, but it can be compressed to a light yellow liquid. Chlorine trifluoride is normally sold compressed. It is an interhalogen, and is very reactive. It can burn plastics, sand, skin, hydrogen sulfide, metals, phosphorus, and sulfur. Since it is a much stronger oxidizing agent than oxygen, it can burn things that normally can't burn, like concrete or sand. It reacts with water very violently to make hydrofluoric acid and hydrochloric acid. It can ignite glass after being in it for a while.