Third Law of Thermodynamics
| Formula / Notation | S → 0 as T → 0 K |
|---|---|
| Also Known As | Third law of thermodynamics, Nernst theorem, absolute entropy law, entropy at absolute zero |
What is Third Law of Thermodynamics?
The Third Law of Thermodynamics states that the entropy of a perfect crystalline substance approaches zero as the temperature approaches absolute zero (0 K). This provides an absolute reference point for entropy calculations. As T → 0 K, S → 0 (for a perfect crystal). This allows calculation of absolute (standard molar) entropies from heat capacity measurements over a temperature range.
Formula & Notation
Other Names / Synonyms: Third law of thermodynamics, Nernst theorem, absolute entropy law, entropy at absolute zero
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
The Third Law of Thermodynamics states that the entropy of a perfect crystalline substance approaches zero as the temperature approaches absolute zero (0 K). This provides an absolute reference point for entropy calculations. As T → 0 K, S → 0 (for a perfect crystal). This allows calculation of absolute (standard molar) entropies from heat capacity measurements over a temperature range.
Calculating standard entropy changes (ΔS° = ΣS°products − ΣS°reactants). Evaluating thermodynamic feasibility of reactions. Low-temperature physics. Cryogenic technology design. Thermodynamic modeling of chemical processes. Understanding entropy as absolute quantity.
Theoretical law — no direct safety concerns. Cryogenic temperatures involved in approaching 0 K: extreme cold hazards.
The formula or notation for Third Law of Thermodynamics is: S → 0 as T → 0 K