Deviation from van't Hoff Behavior of Solids at Low Temperature.

Area of Science:

• Physical Chemistry
• Solid-State Physics
• Thermodynamics

Background:

• Previous research explored low-temperature liquid behavior.
• Molecular interactions in solids create a specific multimolecular potential (kT₀).
• At temperatures below T₀, molecules in solids are localized.

Purpose of the Study:

• To investigate the low-temperature behavior of solids.
• To define and apply a thermal stability temperature (T₀) for solids.
• To extend the van't Hoff equation for solid-state properties.

Main Methods:

• Analysis of molecular interactions and potential energy in solids.
• Extension of the van't Hoff equation with a pre-exponential factor.
• Examination of thermal dissociation, sublimation pressure, and dynamic properties.

Main Results:

• A specific temperature T₀, representing thermal stability, was identified for solids.
• Properties like vapor pressure, diffusion, and reactivity become zero below T₀.
• The extended van't Hoff equation accurately describes experimental data for calcium carbonate, naphthalene, and ice.

Conclusions:

• The temperature T₀ signifies the thermal stability limit of a solid.
• The extended van't Hoff equation provides a framework for understanding solid-state equilibria and dynamics.
• The energy kT₀ is proportional to the molecular pair potential, consistent with liquid behavior.