Lecture Notes on Thermodynamics

Introduction

• Thermodynamics is part of both chemistry and physics.
• While preparing, note that there might be a gap of 1-2 months between the two.
• It is related to heat and motion.

Main Concepts

• System and Surrounding:
  • System: The part under study.
  • Surrounding: Everything except the system.
  • Universe = System + Surrounding.
• Boundaries:
  • Can be real or imaginary.
  • Can be rigid or flexible.
  • Can be diathermic (conducting) or adiabatic (insulating).

Thermodynamic Properties

• Intensive Properties:
  • Do not depend on the size of the system.
  • Examples: Temperature, pressure, density.
• Extensive Properties:
  • Depend on the size of the system.
  • Examples: Mass, volume, energy.

Types of Systems

1. Open System:
   • Can exchange mass and energy.
2. Closed System:
   • Can exchange only energy.
3. Isolated System:
   • Neither mass nor energy is exchanged.

State Variables

• State variables define the state of the gas.
• Examples: Temperature, pressure, volume, enthalpy, entropy.
• Change depends only on the initial and final states.

Types of Thermodynamic Processes

1. Isothermal Process:
   • Temperature remains constant.
2. Isobaric Process:
   • Pressure remains constant.
3. Isochoric Process:
   • Volume remains constant.
4. Adiabatic Process:
   • No heat exchange.

Reversible and Irreversible Processes

• Reversible Process:
  • Occurs in infinitesimal steps.
  • Equilibrium at every step.
• Irreversible Process:
  • Occurs in limited time.
  • Equilibrium only at initial and final states.

Other Important Points

• In any cyclic process:
  • The change of state variables is zero.
• Understanding thermodynamics is essential to study it.