## Lippman's equation

https://doi.org/10.1351/goldbook.L03577
An equation which gives the @E01923@ per unit area of an @I03082@ (electrode): $(\frac{\partial \gamma }{\partial E_{\text{A}}})_{T,p,\mu _{i}\neq \mu }=- Q_{\text{A}}$ where $$\gamma$$ is the @I03088@, $$E_{\text{A}}$$ is the potential of a cell in which the @R05229@ has an interfacial equilibrium with one of the ionic components of A, $$Q_{\text{A}}$$ is the charge on unit area of the @I03082@, $$\mu _{i}$$ is the @C01032@ of the combination of species $$i$$ whose net charge is zero, $$T$$ is the @T06321@ and $$p$$ is the external pressure. Since more than one type of @R05229@ may be chosen, more than one quantity $$Q$$ may be obtained. Consequently $$Q$$ cannot be considered as equivalent to the physical charge on a particular region of the @I03118@. It is in fact an alternative way of expressing a @S06171@ or combination of @S06171@ of charged species.
Sources:
PAC, 1974, 37, 499. (Electrochemical nomenclature) on page 508 [Terms] [Paper]
PAC, 1986, 58, 437. (Interphases in systems of conducting phases (Recommendations 1985)) on page 445 [Terms] [Paper]