What is the branch of chemistry that studies energy changes?

The correct answer, thermodynamics, is the branch of chemistry that focuses on energy changes in chemical reactions and processes. This field examines how energy is transferred and transformed in various systems, making it essential for understanding concepts like enthalpy, entropy, and Gibbs free energy. These principles help chemists predict whether a reaction will occur spontaneously and how the energy of a system changes during chemical reactions.

In thermodynamics, key laws and principles illustrate how energy is conserved and how it influences the direction of chemical reactions. This understanding is crucial for applications ranging from industrial processes to biological systems, where energy changes play a vital role in chemical interactions.

The other branches mentioned do not primarily focus on energy changes: electrochemistry deals with the relationship between chemical reactions and electricity, kinetics studies the rates of reactions and the steps involved, while organic chemistry is centered on the structure, properties, and reactions of carbon-containing compounds. These distinctions highlight why thermodynamics is uniquely positioned as the study of energy changes in chemistry.