Guidance Document
Classes of Incompatible Chemicals

In the table below, the chemicals in column A are incompatible with the corresponding chemicals in
Column B.
Certain combinations of chemicals are explosive, poisonous or hazardous in some way. Experiments
which require the mingling of incompatibles must be designed carefully. Always use minimum
quantities. Store incompatibles away from one another.

Column A
Column B
Alkali and alkaline earth
Water

Carbides
Acids

Hydrides
Halogenated organic compounds

Hydroxides
Halogenating agents

Metals
Oxidizing agents

Oxides


Peroxides



Azides, inorganic
Acids

Heavy metals and their salts

Oxidizing agents


Cyanides, inorganic
Acids

Strong bases


Nitrates, inorganic
Acids

Reducing agents


Nitrites, inorganic
Acids

Oxidizing agents


Organic compounds
Oxidizing agents

Organic acyl halides
Bases


Organic hydroxy and amino compounds





Organic anhydrides
Bases


Organic hydroxy and amino compounds




Organic halogen compounds
Group IA and IIA metals


Aluminum




Organic nitro compounds
Strong bases


Oxidizing agentsa
Reducing agentsa

Chlorates
Ammonia, anhydrous and aqueous

Chromates
Carbon

Chromium trioxide
Metals

Dichromates
Metal hydrides

Halogens
Nitrites

Halogenating agents
Organic compounds

Hydrogen peroxide
Phosphorus

Nitric acid
Silicon

Nitrates
Sulfur

Perchlorates


Peroxides


Permanganates


Persulfates



Reducing agentsa
Oxidizing agentsa

Arsenates

Arsenites

Phosphorus

Selenites

Selenates

Tellurium salts and oxides


Sulfides, inorganic
Acids




a examples of oxidizing and reducing agents are illustrative of common laboratory chemicals; they
are not intended to be exhaustive.


From Prudent Practices in the Laboratory, National Academy Press, 1995