Answer:
the conservation of energy
Step-by-step explanation:
The law of conservation of energy implies that total amount of energy will be equal, before and after a chemical interaction takes place.
It is assumed that the systems are isolated, and that energy is conserved over time. Energy can neither be created nor destroyed.
In the image below, you can see initial energy is converted into heat and work. We refer this toa change in physical or chemical energy to kinetic energy. When measured in controlled circumstances in a lab measuring this energy will always be the same , in a so called isolated system