Last Revised: January 18, 2022
The Fact Sheet below gives hazard information and precautions for working with perchloric acid; however, this information is provided as a supplement to the following SOPs, which also must be read and understood by anyone planning to work with this chemical.
The requirements in Penn's Chemical Hygiene Plan SOP: Corrosives apply to all work involving perchloric acid.
The SOP: Strong Oxidizers applies to perchloric acid when heated.
The SOP: Explosive Compounds applies to the use of perchlorate salts.
Perchloric acid is a colorless, odorless, oily liquid that is extremely corrosive.
Anhydrous perchloric acid and solutions greater than 85% (w/w) present an explosion hazard.
Spills of perchloric acid at concentrations less than 72% (w/w) may evaporate to higher, more hazardous, concentrations.
An explosion or fire may result when concentrated (72+%), heated perchloric comes in contact with organic or combustible materials.
Heating perchloric acid at any concentration leads to potent oxidizing conditions and therefore explosion risk. At elevated temperatures perchloric acid is a strong oxidizer. It becomes unstable, reacts with oxidizable substances, and may detonate.
Toxic chlorine-containing compounds are released when perchloric acid is heated.
Whenever possible, substitute perchloric acid with a less hazardous material.
EHRS approval is required for:
- Purchase of perchloric acid solutions that exceed concentrations of 40% (w/w)
- Any procedure that requires heating of perchloric acid of any concentration
- Store perchloric acid in its original glass bottle and inspect the bottle monthly.
- Date the bottle once it is opened and clearly mark the concentration on the bottle.
- Immediately dispose of a solution of perchloric acid if any discoloration is visible, as this indicates that the acid has begun decomposition and the products are known to be spontaneously explosive.
- Inspect the bottle for the accumulation of a white solid, particularly around the neck joint. The solid is the perchloric acid salt which is shock sensitive and highly reactive.
- Store the acid only in a corrosives-storage cabinet; do not store concentrations equal to or greater than 40% perchloric acid in wood cabinets.
- Store perchloric acid in a secondary container and segregated from other organic reagents.
The following is a list of chemicals that are incompatible with perchloric acid. Do not store perchloric acid with these:
Lead oxide mixtures
|Organic matter (e.g. paper, wood, etc.)
Sulfoxides and Sulfur trioxide
(Source: BU Research Support, Perchloric Acid and Perchlorate Salts SOP, accessed June 28, 2019)
Do not heat perchloric acid of any concentration.
If a protocol requires the heating of a perchloric acid solution, contact EHRS.
- Explosive perchlorate salts can form in exhaust ducts when perchloric acid is heated. For this reason, specialized fume hoods with a neutralizing washdown function are required for all processes in which perchloric acid is exposed to heat. No fume hoods of this type are available on Penn's campus, and thus, the practice of heating perchloric acid is not permitted.
- At elevated temperatures perchloric acid is a strong oxidizer. It becomes unstable, reacts with oxidizable substances, and may detonate.
- Toxic chlorine-containing compounds are released when perchloric acid is heated.
- The heat from exothermic reactions must also be controlled to avoid elevating the temperature of any process involving perchloric acid of greater than 40% concentration.
- Never vacuum-distill perchloric acid. This will form the anhydride, which is extremely unstable.
Do not mix perchloric acid with incompatible materials.
See "Storage" section, above, for a list of incompatible chemicals.
Wear appropriate personal protective equipment.
Even at room temperature and low concentrations (less than 40%), perchloric acid will cause severe burns on contact with skin, eyes or mucous membranes. At a minimum, a cotton lab coat, safety glasses and nitrile gloves must be worn for working with perchloric acid at any concentration. A chemical apron is recommended for work with concentrations greater than 72%.
Do not work alone.
Never use perchloric acid while alone and notify others when in use.
Additional Information on Perchlorates
The perchlorate ion (ClO4-) is highly reactive and potentially explosive. See SOP: Explosive Compounds for guidance on handling potentially explosive materials such as perchlorate salts.
Perchlorates are used in the laboratory in chemical synthesis and in other laboratory procedures including complex ion studies, electrochemical studies, and as drying agents. Perchlorates may also be formed (intentionally or unintentionally) in chemical processes involving perchloric acid.
Examples of perchlorate salts include:
- organic perchlorate salts
- ammonium, alkali metal, and alkali earth perchlorates
- transition metal perchlorates
The most dangerous of the perchlorates are the shock-sensitive covalent salts of heavy metals and organic perchlorates. Ionic alkali metal, alkaline earth metal, and rare earth salts are more stable. Any time perchlorates are in the presence of organic material, there is a potential to form shock-sensitive/explosive material.
Perchlorates are also harmful if ingested, inhaled or absorbed through the skin. Consult the Safety Data Sheet for a material to learn more about its specific toxicity and physical hazards.
Alternative ions should be used in place of perchlorates whenever possible. When it is necessary to use them, the smallest quantity possible must be used.
See SOP: Explosive Compounds for guidance on Approvals, Training Requirements, Facility Requirements, Signage and Labeling, Storage and Transport, Hazard Controls, Waste and Decontamination for all work involving perchlorates.
Perchloric acid stocks should be inspected monthly and prolonged storage should be avoided due to the potential formation of shock sensitive perchloric salts. Do NOT mix waste with organic waste! Contact EHRS for waste pick-up. For more details see the Fact Sheet: Gas-Producing Waste.
General emergency response information can be found at Emergency Info
General procedures for chemicals spill response can be found in Section X: Chemical Spills in this CHP.
Do not hesitate to call EHRS for assistance with spill cleanup for perchloric acid.
24 hours: 215-898-4453
In the event of a small spill, neutralize with 10% sodium carbonate. For large spills, evacuate the area and contact EHRS immediately; as dilute the acid begins to dry, it concentrates and therefore increases the hazard.
Contact Penn Police (511) only if the spill involves a fire, imminent risk of fire, an injury requiring an ambulance, or if there is a hazard that may affect others in the building.
1. Schlit, A. A. Perchloric Acid and Perchlorates; GFS Chemicals Publication, 1979, p.17. (2nd edition in press)