"How do theoretical principles underpin chemical engineering practices, ensuring efficient process design and optimization? Explore the role of thermodynamics, kinetics, and transport phenomena in chemical reactions, unit operations, and process control. Discuss how theoretical frameworks guide reactor design, separation techniques, and product purification, balancing factors like yield, selectivity, and energy efficiency. Consider the integration of computational modeling, such as CFD and molecular simulations, in understanding complex systems and predicting behavior. Furthermore, examine the evolving role of theory in emerging fields like sustainable chemistry and nanotechnology, addressing challenges such as resource conservation, environmental impact mitigation, and innovation in materials design."