What is true about the energy changes in reactions according to the First Law of Thermodynamics?

The First Law of Thermodynamics, also known as the Law of Energy Conservation, states that energy cannot be created or destroyed in an isolated system; it can only change forms. This principle means that during a chemical reaction, the total energy of the system remains constant. Energy can be transformed from one type to another (for example, from potential energy to kinetic energy), but the total amount of energy before and after the reaction will always be the same.

This concept is crucial in understanding thermodynamics in chemistry, as it governs how energy is exchanged in physical and chemical processes. Any energy that seems to be "lost" in a reaction is actually transformed into a different form, such as thermal energy, which might be released into the surroundings. This understanding underlies many practical applications in chemistry, from energy production to reaction spontaneity. Thus, the correct statement aligns perfectly with the core tenet of the First Law of Thermodynamics.