Physical hazards water-reactive chemicals

Physical hazard means a chemical for which there is scientifically valid evidence that it is a combustible liquid, a compressed gas, explosive, flammable, an organic peroxide, an oxidizer, pyrophoric, unstable (reactive) or water-reactive. 

Explain why water reactive chemicals are considered a physical hazard. 

Physical hazard of a chemical— A chemical validated as being or having one of the following characteristics combustible liquid, compressed gas, explosive, flannnable, organic peroxide, oxidizing qualities, pyrophoric, unstable, or water reactive. 

Physical hazard means a chemical that is classified as posing one of the following hazardous effects explosive flammable (gases, aerosols, liquids, or solids) oxidizer (liquid, solid or gas) self-reactive pyrophoric (liquid or solid) self-heating organic peroxide corrosive to metal gas under pressure or in contact with water emits flammable gas. See Appendix B to 1910.1200—Physical Hazard Criteria... 

AH the pertinent physical and chemical properties of chemical materials should be evaluated in relation to the hazards of fire, explosion, toxicity, and corrosion. These properties should include thermal stability, shock sensitivity, vapor pressure, flash point, boiling point, ignition temperature, flammability range, solubility, and reactivity characteristics (e.g., water reactivity and oxidizing potential). 

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