What is the best way to transform a chemical potential energy into internal kinetic energy ?

When a spring is compressed, the energy changes from kinetic to potential. which best describes what is causing this change?

This classification of drug typically changes the brain's chemistry and reduces its ability to create its own endorphins.

Consider the following reactions. (note: (s) = solid, (l) = liquid, and (g) = gas.) mg(s) + ½o2(g) → mgo(s) + 146 kcal/mole h2(g) + ½o2(g) → h2o(g), δh = -57.82 kcal/mole what type of reaction is represented by the previous two examples?