Related Experiment Video
Updated: Aug 13, 2025
06:26
Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
7.2K
Liquid Water: A Single Approach to Its Two Continuous Phase Transitions.
M Simões1, A Steudel1, A P R Santos1
1Departamento de Física, Universidade Estadual de Londrina, Campus Universitário, 86051-990Londrina, PR, Brazil.
The Journal of Physical Chemistry. B
|January 23, 2023
Summary
This study unifies water
Area of Science:
- Thermodynamics
- Physical Chemistry
- Materials Science
Background:
- Liquid water exhibits complex phase transitions, including liquid-gas and liquid-liquid.
- Existing models often treat these transitions separately.
Purpose of the Study:
- To develop a single thermodynamic formalism for continuous phase transitions in liquid water.
- To integrate the two-liquid model (TLM) with van der Waals' concept of excluded volume.
Main Methods:
- Applied fundamental thermodynamics.
- Combined the two-liquid model (TLM) with a thermal-dependent excluded volume (v_ex).
- Separated system thermodynamics into cluster and internal structure components.
Main Results:
- Demonstrated that TLM naturally incorporates an extensive, thermal-dependent excluded volume.
- Showed that mechanical instability yields two critical points, not one.
- Unified the description of liquid-gas and liquid-liquid transitions.
Conclusions:
- The proposed formalism provides a unified framework for water's phase transitions.
- The concept of thermal-dependent excluded volume is key to this unification.
- The findings offer new insights into water's anomalous behavior.
Related Concept Videos
02:44Heating and Cooling Curves
23.1K
When a substance—isolated from its environment—is subjected to heat changes, corresponding changes in temperature and phase of the substance is observed; this is graphically represented by heating and cooling curves.
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
23.1K
01:19Phase Diagram
6.0K
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
6.0K
02:39Phase Diagrams
42.4K
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...
42.4K
02:39Phase Transitions: Melting and Freezing
12.6K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
12.6K
02:39Phase Transitions: Vaporization and Condensation
17.8K
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase...
17.8K
02:31Phase Transitions
19.4K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
19.4K