Laboratory workers must be trained to recognize those chemicals which they may come across which are potentially reactive or explosive. Reactive chemicals, for the purpose of this page, are defined as those substances which can, in contact with air, water or other common substances, vigorously or violently give off heat, energy or toxic gases or vapors. Some of the classes of chemicals which can contain reactive chemicals include:
For a partial listing of chemical incompatabilities, see "Chemical Incompatabilities."
(This document is courtesy of the University of Kansas, Department of Environmental Health and Safety)
Air reactive chemicals are chemicals which react violently in contact with air or oxygen or with compounds containing oxygen. Sometimes air reactive chemicals are called spontaneously combustible or pyrophoric materials. Pyrophoric materials burst into flame spontaneously upon contact with air or oxygen. These materials are sometimes sold in gas cylinders, although they may not be gases themselves. They may be sold packaged under nitrogen or some other inert atmosphere, or they may be created by a chemical reaction in your laboratory. The flame of certain pyrophoric materials is clear and not readily visible. Spontaneous combustion means that the material does not need an ignition source to begin combustion, or to burn.
- alkali metals (potassium, cesium)
- finely divided metal dusts (nickel, zinc, titanium)
- hydrides (barium hydrides, diborane, diisobutyl aluminum hydride).
Water reactive materials can react violently or vigorously in contact with water, wet surfaces, or even the moisture in the air. These chemicals may react to give off a flammable gas (such as hydrogen) or a toxic gas, (such as phosgene) or spontaneously burn or explode. Water is obviously NOT a good choice for putting out fires caused by water reactive chemicals. A class D fire extinguisher is designed to be used to fight fires caused by certain water reactive chemicals.
- Alkali metals (Sodium metal, lithium metal)
- Anhydrides (acetic anhydrides)
- Carbides (calcium carbide)
- Halides (Acetyl chloride, titanium chloride, stannous chloride)
- Hydrides (sodium hydride)
- Organometallics (tetramethyl aluminum)
- oxides (sodium oxides)
- Peroxides (sodium peroxide)
- Phosphides (aluminum phosphide)
- and others (chlorosulfonic acid, aluminum tribromide).
Another list of water reactive chemicals and their toxic by-products
Certain chemicals can form peroxide either upon aging, or upon contact with air or other substances. Some of the peroxides are shock sensitive and can explode if handled less than gingerly, or upon heating. Sometimes peroxides can be present in a solvent and cause no problem until the solvent is evaporated (during distillation, for example) and the peroxides concentrate.
If you work with peroxide formers:
- Date bottle when material is received
- Test for peroxides before every use or every 3 months
- Write the test results on the bottle with the date tested and your initials
- If the material is greater than or equal to 80ppm, it is considered a peroxide hazard, contact Environmental Protection office
- Ethers (Isopropyl ether, ethyl ether, diethyl ether)
Out of the many polymers today, a many generate large amounts of heat upon polymerization, and a few can cause runaway polymerization reaction which can explode. Sometimes the heat buildup can cause bumping, over-booking, or rupture of the container, which can also cause explosive-like damage.
- acrylic acid
- vinyl chloride
Explosives can release extremely large amounts of thermal or physical energy. Explosive can cause a true detonation, which is defined as a shock wave traveling at supersonic speeds. Subsonic shock waves are called deflagrations.
- Acetylanic compounds
- Azo compounds
- Nitro compounds
- Nitro esters
- Other compounds with excess nitrogen
- Strained ring compounds
Please keep in mind when chemical reactions are not properly managed, they can have harmful, or even catastrophic consequences, such as toxic fumes, fires, and explosions. Laboratory personnel should protect themselves by identifying those substances which have the potential to cause violent reactions. Clear identification of containers, proper storage practices, complete training and information on chemicals, and timely removal and disposal of reactive chemicals can significantly reduce the probability of accidents or injuries. For disposal of reactive chemicals, please contact Environmental Affairs staff at x4999 or x2883.
Additional information on working safely with dangerously reactive solids and liquids can be found at:
- Prudent Practices in the Laboratory: Handling and Disposal of Chemicals 5.G.6 Reactive or Explosive Materials Requiring Special Attention
- OSHA's Chemical Reactivity Hazards
- "Dangerously Reactive Liquids and Solids and Their Hazards"
The Canadian Centre for Occupational Health and Safety (CCOHS)
- Article on reactives from "Lab Safety Review"