Thermodynamics
Thermodynamics:
→ Describes macroscopic properties of equilibrium
systems
→ Entirely Empirical
→ Built on 4 Laws and “simple” mathematics
0th Law ⇒ Defines Temperature (T)
1st Law ⇒ Defines Energy (U)
2nd Law ⇒ Defines Entropy (S)
3rd Law ⇒ Gives Numerical Value to Entropy
These laws are UNIVERSALLY VALID, they cannot be circumvented.
Definitions:
• System: The part of the Universe that we choose to study
, 5.60 Spring 2008 Lecture #1 page 1
• Surroundings: The rest of the Universe
• Boundary: The surface dividing the System from the
Surroundings
Systems can be:
• Open: Mass and Energy can transfer between the System and
the Surroundings
• Closed: Energy can transfer between the System and the
Surroundings, but NOT mass
• Isolated: Neither Mass nor Energy can transfer between the
System and the Surroundings
Describing systems requires:
• A few macroscopic properties: p, T, V, n, m, …
• Knowledge if System is Homogeneous or Heterogeneous
• Knowledge if System is in Equilibrium State
• Knowledge of the number of components
Two classes of Properties:
Thermodynamics:
→ Describes macroscopic properties of equilibrium
systems
→ Entirely Empirical
→ Built on 4 Laws and “simple” mathematics
0th Law ⇒ Defines Temperature (T)
1st Law ⇒ Defines Energy (U)
2nd Law ⇒ Defines Entropy (S)
3rd Law ⇒ Gives Numerical Value to Entropy
These laws are UNIVERSALLY VALID, they cannot be circumvented.
Definitions:
• System: The part of the Universe that we choose to study
, 5.60 Spring 2008 Lecture #1 page 1
• Surroundings: The rest of the Universe
• Boundary: The surface dividing the System from the
Surroundings
Systems can be:
• Open: Mass and Energy can transfer between the System and
the Surroundings
• Closed: Energy can transfer between the System and the
Surroundings, but NOT mass
• Isolated: Neither Mass nor Energy can transfer between the
System and the Surroundings
Describing systems requires:
• A few macroscopic properties: p, T, V, n, m, …
• Knowledge if System is Homogeneous or Heterogeneous
• Knowledge if System is in Equilibrium State
• Knowledge of the number of components
Two classes of Properties:
