Chapter 2 Thermodynamics

Thermodynamics Overview

• Thermodynamics: Branch of physics dealing with transformation of heat into mechanical work.

Key Topics Covered

• Thermodynamic System and Types

  • Definition: A system containing a definite quantity of matter bounded by a boundary.

  • Types:

    • Open System: Exchanges both matter and energy.

    • Closed System: Exchanges only energy.

    • Isolated System: Exchanges neither matter nor energy.

• Equation of States

  • Equation relating thermodynamic variables (Pressure, Volume, Temperature).

  • Ideal Gas Law: PV = nRT.

  • Van der Waals Gas Equation: P + (a/V²)(V - b) = RT.

• Work

  • Defined as the method for a system to exchange energy with its surroundings.

  • Types:

    • External Work: Work done by the system on its surroundings.

    • Internal Work: Work done due to intermolecular attractions.

• PV-Diagram

  • Graphical representation of pressure vs volume.

  • Work done by gas during expansion represented by area under the curve.

• First Law of Thermodynamics

  • 9;9;∆Q = ∆U + ∆W9;9;: Heat added to the system is equal to change in internal energy plus work done.

  • Significance:

    • Applicable to any physical/chemical change.

    • Introduces internal energy concept.

    • Method for determining change in internal energy.

  • Limitations:

    • Does not indicate direction of heat transfer.

    • Lacks details on conversion of heat to work.

• Concept of Heat and Specific Heat

  • Heat: Energy transfer due to temperature difference; positive when absorbed, negative when released.

  • Specific Heat: Measures heat capacity; varies with conditions (at constant volume or pressure).

    • CV: Specific heat at constant volume; ∆Q = ∆U.

    • CP: Specific heat at constant pressure; includes work done on the system.

    • Relation: CP = CV + R.

• Thermodynamic Processes

  • Isochoric: Volume remains constant (∆V = 0).

  • Isobaric: Pressure remains constant.

  • Isothermal: Temperature remains constant; ∆U = 0.

  • Adiabatic: No heat exchange; PV^γ = Constant.