Reaction rates almost always increase rapidly as the temperature increases. If the heat evolved in a reaction is not dissipated, the reaction rate can increase until an explosion results. Some chemicals decompose when heated. The heat initiated decomposition of some substances, such as certain peroxides is almost instantaneous. Organic peroxides, are a special class of compounds that have unusual stability problems that make them among the most hazardous substances normally handled in laboratories.
Some substances can detonate as a result of contamination.
Mixtures of perchloric acid with a wide variety of materials, such as organic matter, can be highly unstable. Light and mechanical shock can also be initators of explosive reactions. Hydrogen and chlorine react explosively in the presence of light. Acetylides, ozides, organic nitrates and many peroxides are examples of shock-sensitive materials. Organic peroxides are a class of compounds even more shock sensitive than explosives such as TNT or picric acid.