Thermochemistry is a way to follow energy. In professions like Explosive Engineers, they need to know how to handle explosives so that they can extract materials from the earth needed for making food tastier, as well as needed for computers and cell phones and can be used to build buildings and pave roads. In Explosives (where energy is released) the reaction needs to be Exothermic, other wise it would be a failed explosive and be Endothermic and absorb energy. According to the free dictionary Enthalpy is “A partial measure of the internal energy of a system. Enthalpy cannot be directly measured, but changes in it can be. If an outside pressure on a system is held constant, a change in enthalpy entails a change in the system’s internal energy, plus a change in the system’s volume (meaning the system exchanges energy with the outside world). For example, in endothermic chemical reactions, the change in enthalpy is the amount of energy absorbed by the reaction; in exothermic reactions, it is the amount given off.” This is important because they need to know how big the boom is going to be to get the desired result without overdoing it, or not completing the task the explosive was designed to do. Knowing how much energy is released in reactions is important, 71% of all explosions in the United States is used for coal mining, so Scientist must know the exact output of explosions to break rock, but not enough to destroy everything else. Therefore thermochemistry is crucial to determine the amount of energy released.