# Gibbs-Helmholtz equation

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## Gibbs-Helm·holtz e·qua·tion

(gibz helm'hōltz),**1.**an equation expressing the relationship in a galvanic cell between the chemical energy transformed and the maximal electromotive force obtainable.

**2.**Δ

*G*= Δ

*H*=

*T*[∂Δ

*G*/∂

*T*]

_{P}, where Δ

*G*is the change in Gibbs free energy, Δ

*H*is the change in enthalpy,

*T*is the absolute temperature, and

*P*is the pressure.

## Gibbs,

J. Willard, U.S. mathematician and physicist, 1839-1903.**Gibbs energy of activation**- energy that must be added to that already possessed by a molecule(s) in order to initiate a reaction.

**Gibbs free energy**

**Gibbs theorem**- substances that lower the surface tension of the pure dispersion medium tend to collect in its surface, whereas substances that raise the surface tension tend to remain out of the surface film.

**Gibbs-Donnan equilibrium**- Synonym(s): Donnan equilibrium

**Gibbs-Helmholtz equation**- an equation expressing the relationship in a galvanic cell between the chemical energy transformed and the maximal electromotive force obtainable. Synonym(s): Helmholtz-Gibbs theory

**Helmholtz-Gibbs theory**- Synonym(s): Gibbs-Helmholtz equation

## Helmholtz,

Hermann L.F. von, German physician, physicist, and physiologist, 1821-1894.**Gibbs-Helmholtz equation**- see under Gibbs

**Helmholtz axis ligament**- a ligament forming the axis about which the malleus rotates. Synonym(s):

**axis ligament of malleus**

**Helmholtz coil**

**Helmholtz energy**- energy equivalent to the internal energy minus the entropy contribution.

**Helmholtz keratometer**

**Helmholtz ophthalmoscope**

**Helmholtz theory of accommodation**- the ciliary muscle relaxes for near vision and allows the anterior aspect of the lens to become more convex.

**Helmholtz theory of color vision**- Synonym(s): Young-Helmholtz theory of color vision

**Helmholtz theory of hearing**- that the basilar membrane of the cochlea acts as a resonating structure, recording low tones from its apical turns and high tones from its basal turns. Synonym(s):

**resonance theory of hearing**

**Helmholtz-Gibbs theory**- Synonym(s): Gibbs-Helmholtz equation

**Young-Helmholtz theory of color vision**- see under Young, Thomas

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