Reactives

Some chemicals are hazardous because of their ability to rapidly release large amounts of energy. 

For example, the symbol on the left identifies a material that is an  explosion hazard.  Explosive materials can suddenly, almost instantaneously, release pressure, gas and heat when subjected to sudden shock, pressure or high temperature.

Other materials may become dangerous when mixed with water, air or other chemicals.  These are classified as reactives.  One type of reactive material is a water reactive (designated by the symbol on the right), wich reacts with water to release a gas that is either flammable or toxic.

Another type of reactive is an unstable reactive, which is a chemical that can become self-reactive under conditions of shock, pressure or temperature.