$"$In the realm of chemical engineering, theories serve as foundational pillars guiding the understanding and application of principles governing various chemical processes. These theories encompass a wide array of disciplines, including thermodynamics, fluid mechanics, mass transfer, and reaction kinetics. They provide a framework for analyzing the behavior of chemical systems, predicting process outcomes, and designing efficient industrial processes. From the laws of conservation of mass and energy to the intricacies of reaction mechanisms, theories in chemical engineering form the basis for problem$-$solving, innovation, and advancements in areas ranging from sustainable energy production to pharmaceutical manufacturing."