What foundational theories underpin chemical engineering? From classical thermodynamics to transport phenomena and reaction kinetics, these theories form the bedrock of the discipline. Classical thermodynamics provides essential insights into energy transfer and equilibrium, guiding processes from distillation to reactor design. Transport phenomena elucidate momentum, heat, and mass transfer, crucial in understanding fluid flow in reactors and separation processes like absorption or filtration. Reaction kinetics delve into the rates and mechanisms of chemical reactions, indispensable for optimizing reaction conditions in various industrial applications. These theoretical pillars empower chemical engineers to innovate across sectors$,$ from pharmaceuticals to petrochemicals, shaping our modern world.