Term: electrocapillary equation
https://doi.org/10.1351/goldbook.E01942

Definition:
A form of the Gibbs adsorption equation which includes an expression of the phenomenon of electrocapillarity: \[s\ \mathrm{d}T- \tau \ \mathrm{d}p+\mathrm{d}\gamma +\sigma ^{\alpha }\ \mathrm{d}E+\sum \mathit{\Gamma }_{j}\ \mathrm{d}\mu _{j}=0\] where s is the surface excess of entropy of unit area of interphase, T is the temperature, τ is the thickness or excess volume of unit area of the interphase, p is the external pressure, γ is the interfacial tension, σ^α is the free surface charge density on phase α (areal amount of charge on the surface of phase α), E is the generalized potential, Γj is the surface excess, µj is the chemical potential and j is an electrically neutral component of one or other of the phases; the sum is over all the components but one in each phase.

Related Terms:
1) gibbs adsorption (http://doi.org/10.1351/goldbook.G02627).
2) surface excess (http://doi.org/10.1351/goldbook.S06171).
3) entropy (http://doi.org/10.1351/goldbook.E02149).
4) interphase (http://doi.org/10.1351/goldbook.I03118).
5) interfacial tension (http://doi.org/10.1351/goldbook.I03088).
6) surface charge density (http://doi.org/10.1351/goldbook.S06159).
7) chemical potential (http://doi.org/10.1351/goldbook.C01032).
8) electrocapillarity (http://doi.org/10.1351/goldbook.E01941).

Source: PAC, 1986, 58, 437. 'Interphases in systems of conducting phases (Recommendations 1985)' on page 446 (https://doi.org/10.1351/pac198658030437)

Citation: 'electrocapillary equation' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.E01942

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