What aspect of an explosive defines its efficiency and energy release?

The velocity of detonation is a critical characteristic of an explosive that directly relates to its efficiency and energy release. This velocity refers to the speed at which the reaction front of the explosive travels through the material. A higher velocity of detonation indicates that the explosive can transfer energy more efficiently to surrounding materials, resulting in a more powerful explosion. This is essential for applications such as demolition or propulsion, where the energy released must be maximized to achieve the desired effect.

Other factors, such as physical state, chemical purity, and stability, also play important roles in the overall performance of explosives, but they do not define the efficiency or energy release in the same way. For instance, physical state affects handling and safety, while chemical purity impacts the consistency and reliability of the explosive. Stability is crucial for the safe storage and longevity of explosives but does not influence the inherent energy output. Therefore, the velocity of detonation stands out as the defining aspect directly linked to how explosive materials perform in terms of energy release and overall effectiveness.