Reactivity Alerts

The following reactivityThe tendency of a substance to undergo chemical change. The reactivity of most substances depends on the temperature and pressure of the surroundings, and on the chemicals with which it comes in contact. Under ordinary conditions, innately reactive substances are those that react rapidly with water, air, and other common components of the environment, as well as substances that self-react (decompose or polymerize). alerts are shown on chemical datasheets in the Hazards section, when applicable:

  • Air-ReactiveAir-Reactive

    Likely to react rapidly or violently with dry air or moist air. May generate toxicPoisonous; can injure or kill people or other organisms. and corrosiveLiquid or solid that can destroy human skin or lung tissue or corrode metals. fumesDense, smoke-like vapors given off by fuming materials such as very reactive liquids, gases, or molten metals (for example, concentrated hydrochloric acid or sulfur monochloride). upon exposure to air, or may catch fire.

  • Decomposes at Elevated Temperatures (<120 deg. C)Decomposes at Elevated Temperatures (<120 deg. C)

    Materials that are unstable and can readily decompose—that is, break down into simpler chemical components—under rather mild conditions (where the temperature is less than 120°C [248°F]). The decomposition byproducts may be hazardous. Many of these materials may be stored under refrigeration to stabilize them.

  • ExplosiveExplosive

    A material synthesized or mixed deliberately to allow the very rapid release of chemical energy. Also, a chemical substance that is intrinsically unstable and liable to detonate under conditions that might reasonably be encountered. See topic on Could it burn or explode?

  • Highly FlammableHighly Flammable

    Substances having a flash pointThe lowest temperature at which a liquid gives off enough vapor to be ignited at its surface. of less than 100°F (and mixtures that include those substances). See topic on Could it burn or explode?

  • Known Catalytic ActivityKnown Catalytic Activity

    Substances that have been known to act as catalysts. A catalystA substance that speeds up (catalyzes) a chemical reaction between other substances without itself being chemically changed or consumed. Catalysts are widely used in the chemical industry. For example, an iron/aluminum catalyst is used to synthesize ammonia and a platinum catalyst is used to manufacture nitric acid. is a substance that increases the rate of a chemical reactionThe change that takes place when two or more substances interact to form new substances. by reducing the reaction's activation energy; the catalyst itself is left unchanged by the reaction. Catalysts can increase the rate of reaction so much that reactions that are very slow and non-hazardous (in the absence of a catalyst) become hazardous and release heat or gases very quickly (in the presence of a catalyst). Even small amounts of catalyst can cause a large increase in the reaction rate of the surrounding material.

  • Peroxidizable CompoundPeroxidizable Compound

    Apt to undergo spontaneous reaction with oxygen (a component of air) at room temperature to form peroxides and other products. Ethers and aldehydes are particularly subject to peroxide formation. For example, peroxides can be formed when the ethers or aldehydes react with radical-forming impurities (such as metals), and then react with the oxygen in the air. The peroxides formed are dangerously explosiveA material synthesized or mixed deliberately to allow the very rapid release of chemical energy (that is, an explosion). Also, a chemical substance that is intrinsically unstable and liable to detonate under conditions that might reasonably be encountered., especially when deposited as crystals after evaporation of the liquid portion of the ether or aldehyde. See topic on Could it burn or explode?

  • PolymerizablePolymerizable

    Capable of undergoing self-reactions that release energy. Some polymerizationChemical reaction in which small molecules join to form larger molecules; polymerization reactions typically release heat, and can cause containers to overpressurize. reactions generate a great deal of heat, which can further accelerate the polymerization reaction—a situation called thermal runaway. The products of polymerization reactions are generally less reactiveReadily reacts with other chemicals. than the starting materials.

  • PyrophoricPyrophoric

    Substances that ignite instantly upon exposure to oxygen (air). Generally, these materials are stored in solvents or inertNot chemically reactive (such as neon). atmospheres to prevent exposure to air. Many pyrophoric materials are also water-reactiveCan react vigorously when mixed with water or steam or when spilled into water; the reaction may generate hazardous gas or overpressurize a container., and can produce heat and hazardous gases when they come into contact with water or humid air. See topic on Could it react with water?

  • Radioactive MaterialRadioactive Material

    Spontaneously and continuously emitting ions or ionizing radiationElectromagnetic energy or light, depending on the wavelength, which imparts energy to molecules and atoms. Radiation absorption causes ionization and bond-breaking.. Radioactivity is not a chemical property, but a hazard that exists in addition to the chemical properties of a material.

  • Strong Oxidizing AgentStrong Oxidizing Agent

    Oxidizing agents gain electrons from other substances and are themselves thereby chemically reduced. Strong oxidizing agents accept electrons particularly well from a large range of other substances. The ensuing oxidationA chemical reaction in which oxygen bonds to an element or compound. By extension, a reaction in which one element or compound rises to a higher oxidation state while another drops to a lower oxidation state (the term is used in this sense even when no oxygen whatever is present).-reductionA reaction in which either oxygen is removed from a substance or, in a more general sense, one or more electrons is accepted from another substance. (Can also mean a process in metallurgy by which materials are separated into their wanted and unwanted components from an ore body.) Contrast with Oxidation. reactions may be vigorous or violent, and may release new substances that may take part in additional reactions. Strong oxidizing agents should be kept well separated from strong reducing agents. In some cases, the presence of a strong oxidizing agentOr oxidizer. Substance that yields oxygen readily to support a fire. can greatly increase the severity of a fire.

  • Strong Reducing AgentStrong Reducing Agent

    Reducing agents give up electrons to other substances. They are themselves thereby oxidized. Strong reducing agents donate electrons particularly well to a large range of other substances. The ensuing oxidationA chemical reaction in which oxygen bonds to an element or compound. By extension, a reaction in which one element or compound rises to a higher oxidation state while another drops to a lower oxidation state (the term is used in this sense even when no oxygen whatever is present).-reductionA reaction in which either oxygen is removed from a substance or, in a more general sense, one or more electrons is accepted from another substance. (Can also mean a process in metallurgy by which materials are separated into their wanted and unwanted components from an ore body.) Contrast with Oxidation. reactions may be vigorous or violent and may generate new substances that take part in further reactions.

  • Water-ReactiveWater-Reactive

    Substances that may react rapidly or violently with liquid water and steam, producing heat (or fire) and—in many cases�toxicPoisonous; can injure or kill people or other organisms. or flammableEasy to ignite and burns readily. reactionThe change that takes place when two or more substances interact to form new substances. products. See topic on Could it react with water?

Seeing Reactivity Alerts for a Chemical

  1. Find and open the chemical's datasheet. How do I find a chemical datasheet?
  2. Scroll down to the Hazards section. Under Reactivity Alerts, find the reactive hazards of that chemical (if any). See exampleSee example

    CAMEO 365betÓéŔÖ displays three reactivity alerts for 1,3-butadiene:

    CAMEO 365betÓéŔÖ displays three reactivity alerts for 1,3-butadiene: Highly Flammable, Polymerizable, and Peroxidizable Compound.