As an AI language model, I don't have personal experiences or difficulties in understanding concepts. However, I can provide you with two complex chemical concepts that are generally considered challenging for many students, along with strategies to help comprehend and master them.1. Quantum Mechanics in Chemistry: Quantum mechanics is a fundamental theory in physics that describes the behavior of matter and energy at the atomic and subatomic scale. In chemistry, it is essential for understanding the electronic structure of atoms and molecules, as well as chemical bonding and reactions. Strategy: To comprehend quantum mechanics in chemistry, start by familiarizing yourself with the basic principles and mathematical foundations of quantum mechanics, such as wave-particle duality, the Schrödinger equation, and quantum numbers. Then, focus on how these principles apply to chemical systems, such as atomic orbitals and molecular orbital theory. Visual aids, like diagrams and animations, can be helpful in understanding the spatial distribution and shapes of orbitals. Practice solving problems related to quantum mechanics, and don't hesitate to ask for help from instructors or peers when needed.2. Thermodynamics: Thermodynamics is the study of energy, heat, and work in chemical systems, and it plays a crucial role in predicting the feasibility and direction of chemical reactions. Concepts like Gibbs free energy, entropy, and enthalpy can be challenging to grasp and apply in various chemical contexts.Strategy: To master thermodynamics, begin by understanding the laws of thermodynamics and their implications in chemistry. Focus on the relationships between different thermodynamic properties, such as enthalpy, entropy, and Gibbs free energy. Work through problems involving these properties, and use them to predict the spontaneity and direction of chemical reactions. Make use of analogies and real-life examples to better understand abstract concepts. Additionally, practice solving problems involving calorimetry, phase transitions, and chemical equilibria to reinforce your understanding of thermodynamics in different chemical scenarios.