Reactive Hazards

Oxidising Agents

Oxidizing agents are chemicals that bring about an oxidation reaction. The oxidizing agent may provide oxygen to the substance being oxidized (in which case the agent has to be oxygen or contain oxygen) or receive electrons being transferred from the substance undergoing oxidation (chlorine is a good oxidizing agent for electron-transfer purposes, even
though it does not contain oxygen). The intensity of the oxidation reaction depends on the oxidizing-reducing potential of the material involved. Fire or explosion is possible when strong oxidizing agents come into contact with easily oxidizable compounds, such as metals, metal hydrides or organics. Because oxidizing agents possess varying degrees of instability, they can be explosively unpredictable.  

Examples of Oxidizing Agents

Gases Fluorine, chlorine, ozone, nitrous oxide, oxygen
Liquids Hydrogen peroxide, nitric acid, perchloric acid, bromine, sulphuric acid
Solids Nitrites, nitrates, perchlorates, chromates, dichromates, picrates, permanganates, hypochlorites, bromates, iodates, chlorites, chlorates, persulphates.



Explosives cause sudden, almost instantaneous release of pressure, gas, and heat when subjected to sudden adverse conditions. Heat, light, mechanical shock, detonation, and certain catalysts can initiate explosive reactions. Compounds containing the functional groups azide, acetylide, diazo, nitroso, haloamine, peroxide, and ozonide are sensitive to shock and heat and can explode violently.

Peroxide Forming Compounds

Generally, organic peroxides are low-powered explosives that are sensitive to shock, sparks, and heat. Some organic compounds such as ethers, tetrahydrofuran, and dioxan can react with oxygen from the air forming unstable peroxides. Peroxide formation can occur slowly under normal storage conditions -limited access to air and exposure to light. These accumulated peroxides can violently explode when exposed to shock, friction, or heat especially when concentrated and heated by distillation. Bretherick ("Hazards in the Chemistry Laboratory") points out the particular danger from peroxide formation by di-isopropyl ether.


Water Reactive Compounds

These compounds react with water or moisture in the air releasing heat or flammable, toxic gas. Examples include alkali metals, alkaline earth metals, carbides, hydrides, inorganic chlorides, nitrides, peroxides, and phosphides.


Toxic Hazards from Mixtures

Toxic gases may be evolved following the mixture of some chemicals e.g.

Chemical A Chemical B Product
Arsenical materials Any reducing agent Arsine
Azides Acids Hydrogen Azide
Cyanides Acids Hydrogen Cyanide
Hypochlorites Acids Chlorine or hypochlorous acid
Nitrates Sulphuric Acid Nitrogen Dioxide
Nitric Acid Copper, brass, any heavy metals Nitrogen Dioxide
Nitrites Acids Nitrous fumes
Phosphorus Caustic alkalis or reducing agents Phosphine
Selenides Reducing agents Hydrogen Selenide
Sulphides Acids Hydrogen Sulphide
Tellurides Reducing agents Hydrogen Telluride


Reactive Hazards from Mixtures

Many chemicals may react violently on mixing accidentally or intentionally.

Chemical Incompatibles

Acetic acid

Chromic acid, nitric acid, hydroxyl compounds, ethylene glycol, perchloric acid, peroxides, permanganates


Chlorine, bromine, copper, fluorine, silver, mercury


Concentrated nitric and sulphuric acid mixtures

Alkali and alkaline earth metals (such as powdered aluminium or magnesium, calcium, lithium, sodium, potassium)

Water, carbon tetrachloride or other chlorinated hydrocarbons, carbon dioxide, halogens

Ammonia (anhydrous)

Mercury (in manometers, for example), chlorine, calcium hypochlorite, iodine, bromine, hydrofluoric acid (anhydrous)

Ammonium nitrate

Acids, powdered metals, flammable liquids, chlorates, nitrites, sulphur, finely divided organic combustible materials


Nitric acid, hydrogen peroxide

Arsenical materials

Any reducing agent




See chlorine

Calcium oxide


Carbon (activated)

Calcium hypochlorite, all oxidizing agents

Carbon tetrachloride



Ammonium salts, acids, powdered metals, sulphur, finely divided organic or combustible materials

Chromic acid and chromium

Acetic acid, naphthalene, camphor, glycerol, alcohol, flammable liquids in general


Ammonia, acetylene, butadiene, butane, methane, propane (or other petroleum gases), hydrogen, sodium carbide, benzene, finely divided metals, turpentine

Chlorine dioxide

Ammonia, methane, phosphine, hydrogen sulphide


Acetylene, hydrogen peroxide

Cumene hydroperoxide

Acids (organic or inorganic)



Flammable liquids

Ammonium nitrate, chromic acid, hydrogen peroxide, nitric acid, sodium peroxide, halogens


All other chemicals

Hydrocarbons (such as butane, propane, benzene)

Fluorine, chlorine, bromine, chromic acid, sodium peroxide

Hydrocyanic acid

Nitric acid, alkali

Hydrofluoric acid (anhydrous)

Ammonia (aqueous or anhydrous)

Hydrogen peroxide

Copper, chromium, iron, most metals or their salts, alcohols, acetone, organic materials, aniline, nitromethane, combustible materials

Hydrogen sulphide

Fuming nitric acid, oxidizing gases


Acids, activated carbon


Acetylene, ammonia (aqueous or anhydrous), hydrogen


Acetylene, fulminic acid, ammonia


Sulphuric acid

Nitric acid (concentrated)

Acetic acid, aniline, chromic acid, hydrocyanic acid, hydrogen sulphide, flammable liquids, flammable gases, copper, brass, any heavy metals




inorganic bases, amines

Oxalic acid

Silver, mercury


Oils, grease, hydrogen: flammable liquids, solids or gases

Perchloric acid

Acetic anhydride, bismuth and its alloys, alcohol, paper, wood, grease, oils

Peroxides, organic

Acids (organic or mineral), avoid friction, store cold

Phosphorus (white)

Air, oxygen, alkalis, reducing agents


Carbon tetrachloride, carbon dioxide, water

Potassium chlorate

Sulphuric and other acids

Potassium perchlorate (see also chlorates)

Sulphuric and other acids

Potassium permanganate

Glycerol, ethylene glycol, benzaldehyde, sulphuric acid


Reducing agents


Acetylene, oxalic acid, tartaric acid, ammonium compounds, fulminic acid


Carbon tetrachloride, carbon dioxide, water

Sodium nitrite

Ammonium nitrate and other ammonium salts

Sodium peroxide

Ethyl or methyl alcohol, glacial acetic acid, acetic anhydride, benzaldehyde, carbon disulfide, glycerin, ethylene glycol, ethyl acetate, methyl acetate, furfural



Sulphuric acid

Potassium chlorate, potassium perchlorate, potassium permanganate (similar compounds of light metals, such as sodium, lithium)


Reducing agents