Final answer:
4. Thermochemistry is the branch of chemistry focused on the energy changes during chemical reactions, pivotal in understanding various scientific and technical applications.
Step-by-step explanation:
The branch of chemistry that is concerned with energy changes is thermochemistry. Thermochemistry describes the energy changes that take place during chemical reactions, including the heat absorbed or released as products are formed from reactants. This field is fundamental to many scientific and technical disciplines, as it allows scientists and engineers to understand and quantify energy changes and their implications for everything from living organisms to industrial processes.
The branch of chemistry concerned with energy changes is Thermochemistry. Thermochemistry is a branch of chemical thermodynamics and it deals with the relationships between heat, work, and other forms of energy in the context of chemical and physical processes. Thermochemistry allows us to understand and quantify the energy changes that occur during chemical reactions, such as the amount of heat absorbed or released.