In chemical engineering, what fundamental theories serve as the cornerstone? The field relies on principles such as thermodynamics, transport phenomena, reaction kinetics, and process control. Thermodynamics elucidates energy transfer and phase equilibria crucial for designing chemical processes. Transport phenomena explain the movement of mass, energy, and momentum in fluids and solids. Reaction kinetics govern the rates of chemical reactions, vital for reactor design. Process control theories enable the optimization and automation of industrial processes. These foundational theories form the essence of chemical engineering practice.