How do fundamental theories in chemical engineering, such as thermodynamics, transport phenomena, and reaction kinetics, underpin the design and optimization of chemical processes? Explore how these principles govern the behavior of materials and energy within chemical systems, enabling the prediction and control of processes in industries ranging from petroleum refining to pharmaceutical manufacturing. Consider the interplay between macroscopic and molecular$-$level phenomena, and how advancements in theoretical frameworks, computational modeling, and experimental techniques continually enhance our understanding and application of chemical engineering principles. Additionally, discuss the importance of interdisciplinary approaches in integrating theory with practice to address complex challenges in sustainability, safety, and innovation within the field