Explosives have functions designed to rapidly change their (normally solid) state into a very hot gas, to produce a sudden and violent physical effect.
The change of state takes place almost instantaneously (producing a rapid increase in volume as the solid becomes gas, and a subsequent expansion due to the change that is accompanied by a great release of chemical energy in the form of heat) reaching several miles of degrees . It is this rapid and drastic increase in volume that produces the desired physical effect.
In the case of high-yield explosives, their effect is to destroy anything nearby and, in the case of low-yield explosives, it produces a massive kinetic force. The release of energy is the same, but in the case of low-yield explosives, the molecules are designed to change fractionally more slowly, to produce a ‘powerful push’, rather than a rapid burst.
Although explosives can behave violently when properly activated, they are designed to be stable and insensitive under normal surface conditions. This means that they can be handled and transported by land and sea quite safely, as long as they are not subjected to violent shocks, such as a high speed traffic accident, or worse, they come into contact with a fire. Some high-performance explosives can ignite at temperatures as low as 200 ° C.
There are 6 divisions in Class 1, showing how explosives react and how they behave once activated. Items are also mapped to one of the 13 letters in the Compatibility Group, basically to indicate which types can safely travel alongside other types.
Division 1.1 Mass Explosion Hazard
Division 1.2 Projection Risk Only
Division 1.3 Fire and Slight Explosion Hazard or Slight Projection Hazard
Division 1.4 Minimal risk
Division 1.5 Explosive agents
Division 1.6 Very insensitive triggers

Bibliography: Class 1 Explosives. [Dangerous cargo] (January 2021). Recovered from https://www.es.dsv.com/