Profile Analysis Tensiometers
Advanced instruments for surface and interfacial characterization.
Surface & Interfacial Tension · Chapter 02
Interfacial Thermodynamics
Thermodynamic concepts describing interfacial free energy, surface excess and adsorption at phase boundaries.
Chapter contents
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Scientific topics
Chapter Overview
Thermodynamic descriptions of interfaces and adsorption.
Interfacial thermodynamics provides a framework for describing the energetic state and composition of a phase boundary. Surface and interfacial tension can be treated as thermodynamic quantities associated with the creation of additional interfacial area.
Gibbs introduced the concept of a dividing surface to separate the bulk phases mathematically while assigning excess quantities to the interface. This forms the basis for surface excess and the Gibbs adsorption equation.
Thermodynamics Library
Explore interfacial thermodynamics.
Focused articles covering the thermodynamic quantities and models used to describe interfaces and adsorption.
01
Thermodynamic definition
Thermodynamic Definition of Interfacial Tension
For a reversible increase in interfacial area at constant temperature, pressure and component amounts, interfacial tension is the derivative of Gibbs free energy with respect to area.
Gibbs free energyInterfacial areaγ
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02
Adsorption layers
Surface Pressure
Surface pressure expresses the reduction in tension of an adsorption-covered interface relative to a reference interface such as the clean solvent surface.
Surface pressureReference interfaceAdsorption layer
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03
Interfacial model
The Gibbs Dividing Surface
Gibbs replaces the finite interfacial region with an idealized mathematical dividing surface that separates bulk contributions from interfacial excess quantities.
Gibbs dividing surfaceInterfaceBulk phases
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Interfacial composition
Surface Excess
Surface excess concentration describes the amount of a component assigned to the interface relative to the corresponding bulk phases.
Surface excessΓAdsorption
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05
Adsorption thermodynamics
Gibbs Adsorption Equation
The Gibbs adsorption equation relates changes in interfacial tension to surface excess and changes in the chemical potentials of components.
Gibbs adsorption equationSurface excessChemical potential
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