Related Experiment Video
Updated: Jun 13, 2026
09:42
Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Relationship between structure, entropy, and diffusivity in water and water-like liquids
Manish Agarwal1, Murari Singh, Ruchi Sharma
1Department of Chemistry, Indian Institute of Technology-Delhi, New Delhi 110016, India.
The Journal of Physical Chemistry. B
|May 5, 2010
Summary
This study compares excess entropy anomalies and diffusivity scaling in water, ionic melts, and a soft-core fluid. While all systems follow the excess entropy scaling law, water exhibits a narrower anomaly range and slight deviations in scaling parameters.
Area of Science:
- Physical Chemistry
- Computational Fluid Dynamics
- Materials Science
Background:
- Water and certain ionic melts exhibit anomalous thermodynamic and transport properties.
- Excess entropy (S(e)) is a key thermodynamic quantity related to liquid structure and dynamics.
- Diffusivity anomalies are often linked to structural changes and excess entropy.
Purpose of the Study:
- To compare the excess entropy anomaly and its scaling relationship with diffusivity across diverse liquid systems.
- To investigate the universality of the excess entropy-diffusivity scaling law.
- To explore the influence of system-specific interactions on these anomalous behaviors.
Main Methods:
- Molecular dynamics simulations of water (SPC/E, TIP3P), SiO(2), BeF(2), and a 2SRP fluid.
- Analysis of excess entropy (S(e)) and diffusivity (D*) as a function of density and temperature.
- Application of the Rosenfeld excess entropy scaling relation: D* = A exp(alphaS(e)).
Main Results:
- An excess entropy anomaly was observed in both water models, with a significantly narrower density range compared to ionic melts and the 2SRP fluid.
- All simulated systems adhered to the excess entropy-diffusivity scaling relation.
- Water showed a minor isochore dependence in the scaling parameter alpha, which was amplified when using pair correlation approximants for S(e).
Conclusions:
- The excess entropy anomaly is a common feature in liquids with water-like anomalies, but its manifestation varies with interaction potentials.
- The diffusivity-excess entropy scaling is a robust relationship across diverse liquid systems.
- Isochoric temperature dependence of diffusivity is linked to the entropic contribution, with pair correlation functions providing insights into this relationship.
Related Concept Videos
02:05Entropy and Solvation
The process of surrounding a solute with solvent is called solvation. It involves evenly distributing the solute within the solvent. The rule of thumb for determining a solvent for a given compound is that like dissolves like. A good solvent has molecular characteristics similar to those of the compound to be dissolved. For example, polar solutions dissolve polar solutes, and apolar solvents dissolve apolar solutes. A polar solvent is a solvent that has a high dielectric constant (ϵ ≥ 15); an...
02:39Entropy
Salt particles that have dissolved in water never spontaneously come back together in solution to reform solid particles. Moreover, a gas that has expanded in a vacuum remains dispersed and never spontaneously reassembles. The unidirectional nature of these phenomena is the result of a thermodynamic state function called entropy (S). Entropy is the measure of the extent to which the energy is dispersed throughout a system, or in other words, it is proportional to the degree of disorder of a...
01:18Entropy
The first law of thermodynamics is quantitatively formulated via an equation relating the internal energy of a system, the heat exchanged by it, and the work done on it. A quantitative formulation of the second law of thermodynamics leads to defining a state function, the entropy.
When an ideal gas expands isothermally, the disorder in the gas increases. From the molecular perspective, the gas molecules have more volume to move around in.
Consider an infinitesimal step in the expansion, which...
When an ideal gas expands isothermally, the disorder in the gas increases. From the molecular perspective, the gas molecules have more volume to move around in.
Consider an infinitesimal step in the expansion, which...
02:38Third Law of Thermodynamics
A pure, perfectly crystalline solid possessing no kinetic energy (that is, at a temperature of absolute zero, 0 K) may be described by a single microstate, as its purity, perfect crystallinity,and complete lack of motion means there is but one possible location for each identical atom or molecule comprising the crystal (W = 1). According to the Boltzmann equation, the entropy of this system is zero.
02:56Intermolecular Forces and Physical Properties
03:00Solubility
Solution, Solubility, and Solubility Equilibrium
A solution is a homogeneous mixture composed of a solvent, the major component, and a solute, the minor component. The physical state of a solution—solid, liquid, or gas—is typically the same as that of the solvent. Solute concentrations are often described with qualitative terms such as dilute (of relatively low concentration) and concentrated (of relatively high concentration).
In a solution, the solute particles (molecules, atoms, and/or ions)...
A solution is a homogeneous mixture composed of a solvent, the major component, and a solute, the minor component. The physical state of a solution—solid, liquid, or gas—is typically the same as that of the solvent. Solute concentrations are often described with qualitative terms such as dilute (of relatively low concentration) and concentrated (of relatively high concentration).
In a solution, the solute particles (molecules, atoms, and/or ions)...