Laws of Thermodynamics

Laws of Thermodynamics

Zeroth Law of Thermodynamics

• If two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.
• Allows the definition of a temperature scale, such as Celsius or Kelvin.

First Law of Thermodynamics

• Energy cannot be created or destroyed, only converted from one form to another.
• The total energy of an isolated system remains constant.
• Mathematically expressed as: ΔE = Q - W, where ΔE is the change in energy, Q is the heat added, and W is the work done.

Second Law of Thermodynamics

• The total entropy of an isolated system always increases over time.
• Entropy is a measure of disorder or randomness.
• Mathematically expressed as: ΔS = ΔQ / T, where ΔS is the change in entropy, ΔQ is the heat added, and T is the temperature.

Third Law of Thermodynamics

• As the temperature of a system approaches absolute zero, the entropy of the system approaches a minimum value.
• Provides a fundamental limit on the efficiency of any heat engine.

Thermodynamic Systems

• Isolated System: No energy or matter can be exchanged with the surroundings.
• Closed System: Energy can be exchanged with the surroundings, but no matter can be exchanged.
• Open System: Both energy and matter can be exchanged with the surroundings.

Thermodynamic Processes

• Isothermal Process: Temperature remains constant.
• Adiabatic Process: No heat is transferred between the system and surroundings.
• Isobaric Process: Pressure remains constant.
• Isochoric Process: Volume remains constant.

Thermodynamic Properties

• Internal Energy (U): The total energy of a system.
• Enthalpy (H): A measure of the total energy of a system, including the energy associated with the pressure and volume of a system.
• Entropy (S): A measure of the disorder or randomness of a system.
• Free Energy (G): A measure of the energy available to do work in a system.

Thermodynamic Applications

• Heat Engines: Convert thermal energy into mechanical energy.
• Refrigeration: Transfer heat from a cold body to a hot body.
• Thermodynamic Cycles: A series of processes that allow for the continuous conversion of energy.

Laws of Thermodynamics

Zeroth Law of Thermodynamics

• Establishes a temperature scale, such as Celsius or Kelvin, by defining thermal equilibrium.
• States that if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.

First Law of Thermodynamics

• Energy is conserved, meaning it cannot be created or destroyed, only converted from one form to another.
• The total energy of an isolated system remains constant.
• Mathematically expressed as ΔE = Q - W, where ΔE is the change in energy, Q is the heat added, and W is the work done.

Second Law of Thermodynamics

• The total entropy of an isolated system always increases over time.
• Entropy is a measure of disorder or randomness.
• Mathematically expressed as ΔS = ΔQ / T, where ΔS is the change in entropy, ΔQ is the heat added, and T is the temperature.

Third Law of Thermodynamics

• The entropy of a system approaches a minimum value as the temperature approaches absolute zero.
• Provides a fundamental limit on the efficiency of any heat engine.

Thermodynamic Systems

Types of Systems

• Isolated System: No energy or matter can be exchanged with the surroundings.
• Closed System: Energy can be exchanged with the surroundings, but no matter can be exchanged.
• Open System: Both energy and matter can be exchanged with the surroundings.

Thermodynamic Processes

• Isothermal Process: Temperature remains constant.
• Adiabatic Process: No heat is transferred between the system and surroundings.
• Isobaric Process: Pressure remains constant.
• Isochoric Process: Volume remains constant.

Thermodynamic Properties

• Internal Energy (U): The total energy of a system.
• Enthalpy (H): A measure of the total energy of a system, including the energy associated with the pressure and volume of a system.
• Entropy (S): A measure of the disorder or randomness of a system.
• Free Energy (G): A measure of the energy available to do work in a system.

Thermodynamic Applications

• Heat Engines: Convert thermal energy into mechanical energy.
• Refrigeration: Transfer heat from a cold body to a hot body.
• Thermodynamic Cycles: A series of processes that allow for the continuous conversion of energy.