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Wyatt's Notes — University

Physical Chemistry

Physical Chemistry

Physical chemistry examines the physical principles underlying chemical systems. It draws on mathematics and physics to explain why reactions occur, how fast they proceed, and what determines the stability of molecular structures. Core topics include thermodynamics, chemical kinetics, quantum mechanics, and spectroscopy.

Key Concepts

Thermodynamics describes the energy changes and spontaneity of reactions through quantities such as enthalpy (HH), entropy (SS), and Gibbs free energy (GG). The relationship ΔG=ΔH−TΔS\Delta G = \Delta H - T \Delta S determines whether a process is thermodynamically favourable at a given temperature. Chemical kinetics, by contrast, concerns the rate at which reactions occur and the mechanisms by which they proceed.

Worked Example: Calculating Gibbs Free Energy

Consider a reaction with ΔH=−92.2 kJ mol−1\Delta H = -92.2 \text{ kJ mol}^{-1} and ΔS=−198.7 J K−1mol−1\Delta S = -198.7 \text{ J K}^{-1} \text{mol}^{-1} at T=298 KT = 298 \text{ K}. Converting entropy to kJ: ΔS=−0.1987 kJ K−1mol−1\Delta S = -0.1987 \text{ kJ K}^{-1} \text{mol}^{-1}. Applying the equation:

ΔG=−92.2−(298)(−0.1987)=−92.2+59.2=−33.0 kJ mol−1\Delta G = -92.2 - (298)(-0.1987) = -92.2 + 59.2 = -33.0 \text{ kJ mol}^{-1}

Since ΔG<0\Delta G < 0, the reaction is spontaneous under these conditions.

Overview

University-level physical chemistry notes covering thermodynamics, kinetics, quantum chemistry, and spectroscopy.

Topics Covered

  • Thermodynamics: Enthalpy, entropy, Gibbs free energy, phase equilibria
  • Kinetics: Rate laws, reaction mechanisms, catalysis, Arrhenius equation
  • Quantum Chemistry: Wave functions, Schrodinger equation, molecular orbitals
  • Spectroscopy: IR, UV-Vis, NMR, mass spectrometry

Prerequisites

  • General chemistry (first-year university level)
  • Calculus (differentiation, integration, differential equations)
  • Linear algebra (matrices, eigenvalues)
  • Basic physics (mechanics, thermodynamics)

How to Use These Notes

Start with the introductory sections to build foundational knowledge, then progress to more advanced topics. Each section includes worked examples and practice problems.

Use the sidebar to browse topics, or start with the introductory pages linked from the sidebar.

Additional Resources

Each section includes:

  • Detailed explanations of key concepts
  • Worked examples with step-by-step solutions
  • Practice problems with answers
  • Common pitfalls and how to avoid them
  • Connections to other areas of physical chemistry

Study Tips

  1. Build a strong foundation: Ensure you understand the basic concepts before moving to advanced topics
  2. Practice regularly: Physical chemistry requires active practice, not just reading
  3. Work through derivations: Practice deriving equations from first principles
  4. Use mathematical tools: Familiarise yourself with calculus and linear algebra techniques
  5. Connect theory to experiment: Relate theoretical concepts to experimental observations