A powerful oxidizer and highly corrosive substance perchloric acid is a clear liquid with no odor. Mainly

English: Appr. 40 ml of 60% perchloric acid.
English: Appr. 40 ml of 60% perchloric acid. (Photo credit: Wikipedia)

produced as a precursor to ammonium perchlorate, used as rocket fuel. There are various other uses including in electropolishing.

When below 50% acid by mass perchloric acid has more corrosive property than its oxidizing nature, 50 to 72% acid by mass the danger of its oxidizing property is much greater than its corrosiveness.

At or above 73% acid by mass perchloric acid becomes very strong oxidizer that salts formed from oxidation may explode even by friction or shock.

One of the worst accident involving Perchloric acid is an explosion at O’Connor Electro-Plating Company in Los Angeles, California on February 20 1947. This accident resulted in 17 deaths, 100 buildings damaged, and a 22 foot deep crater formed in the ground.

IMDG Code lists Perchloric Acid as below

  1.  UN 1802 Class 8 (5.1)  PERCHLORIC ACID with not more than 50% acid, by mass
  2.  UN 1873 Class 5.1 (8)  PERCHLORIC ACID with more than 50% but not more than 72% acid, by mass

PERCHLORIC ACID, with more than 72% acid by mass is prohibited for transport by ships.