We present experimental and computational results that explain some aspects of measured energy release in explosions of unconfined trinitrotoluene [TNT, C(6)H(2)(NO(2))(3)CH(3)], and an aluminum-containing explosive formulation, and show how this energy release can influence shock wave velocities in air. In our interpretation, energy release is divided into early, middle, and late time regimes. An explanation is provided for the interdependence of the time regimes and their influence on the rate at which energy (detonation/explosion and afterburn) is released. We use a merging of the thermodynamic and chemical kinetic processes that predicts how chemical kinetics may determine the time delay of the afterburn of combustible gases produced by the initial detonation/explosion/fast reaction. The thermodynamic computer code CHEETAH is used to predict gaseous and solid products of early time energy release, and a chemical kinetic reaction mechanism (CHEMKIN format) is used to describe the subsequent afterburn of the gas phase products in air. Results of these calculations are compared with field measurements of unconfined explosions of 2 kg charge weights of TNT and an aluminum-containing explosive formulation.