Tercera Ley de la Termodinamica | Science Time

Understanding the Third Law of Thermodynamics

Overview of Previous Laws

• The video reviews previous laws of thermodynamics:

• Zeroth Law: Establishes the existence of heat.

• First Law: Energy cannot be created or destroyed, only transformed.

• Second Law: Discusses energy flow and introduces entropy, which is the tendency from order to disorder.

Introduction to the Third Law

• The focus shifts to the Third Law of Thermodynamics, highlighting:

• The coldest known place in the universe, Nebula Boomerang, at approximately -272°C (1 Kelvin).

• Achievements on Earth where scientists have cooled sodium and potassium molecules to about 500 Nano Kelvin.

Key Concepts of the Third Law

• The Third Law defines absolute zero (0 K):

• At absolute zero, all physical processes cease.

• Entropy reaches a minimum constant value.

• It emphasizes that reaching absolute zero is experimentally impossible due to:

• The Second Law of Thermodynamics, which states heat flows from higher energy objects to lower energy ones.

Historical Context and Development

• Developed by chemist Walter Nernst between 1906 and 1912:

• Often referred to as Nernst's theorem or postulate.

• Nernst's law states that at absolute zero, entropy is a defined constant:

• A system at this temperature exists in a fundamental state with entropy determined solely by its degeneracy.

Implications and Conclusion

• While seemingly simple like the Zeroth Law, it completes our understanding of nature and heat:

• Highlights that achieving isothermality (temperature equal to zero) in finite steps is impossible.