Donnan Potential
Compute the equilibrium potential at 25 °C from the inside-to-outside concentration ratio. The base-10 Nernst factor is 59.16 mV per tenfold concentration gradient and is divided by ion valence.
Description
Compute the equilibrium potential at 25 °C from the inside-to-outside concentration ratio. The base-10 Nernst factor is 59.16 mV per tenfold concentration gradient and is divided by ion valence.
Donnan Potential is a focused biology tool that compute the equilibrium potential at 25 °C from the inside-to-outside concentration ratio. The base-10 Nernst factor is 59.16 mV per tenfold concentration gradient and is divided by ion valence. It calculates locally from the values you enter and exposes the result without changing the source observations.1
When to use Donnan Potential
Use Donnan Potential when you need to compute the equilibrium potential at 25 °C from the inside-to-outside concentration ratio. The base-10 Nernst factor is 59.16 mV per tenfold concentration gradient and is divided by ion valence. Enter Valence z, Inside concentration, and Outside concentration using the definitions and units below so the result can be reproduced.
- Valence z
- An integer count or setting from -3 through 3.
- Inside concentration
- A finite measured or assumed value, expressed in M.
- Outside concentration
- A finite measured or assumed value, expressed in M.
How Donnan Potential calculates the result
The published tool contract uses this rule: Compute the equilibrium potential at 25 °C from the inside-to-outside concentration ratio. The base-10 Nernst factor is 59.16 mV per tenfold concentration gradient and is divided by ion valence.1
- Donnan potential
- Signed potential in millivolts.
Limitations of Donnan Potential
A ratio or percentage can conceal the scale of its numerator and denominator and becomes sensitive to measurement error when the denominator is small. Valence z must remain between -3 and 3.
Alternative or Complementary measurements
Retain the original Valence z, Inside concentration, and Outside concentration values and their units alongside the result. Gibbs-Donnan Ratio is useful when you instead need to compute the Gibbs-Donnan ratio as the concentration of permeant ion inside a cell divided by its concentration outside. Nernst Membrane Potential provides another view by helping you compute the Nernst equilibrium potential at 37 degrees Celsius in millivolts: EMV = (61.5 / z) x log10(outsideConcentration / insideConcentration), signed positive for outward cation gradient driving force.
References
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Donnan potential — Wikipedia contributors
Similar or alternative tools
- Gibbs-Donnan Ratio
Compute the Gibbs-Donnan ratio as the concentration of permeant ion inside a cell divided by its concentration outside.
- Nernst Membrane Potential
Compute the Nernst equilibrium potential at 37 degrees Celsius in millivolts: EMV = (61.5 / z) x log10(outsideConcentration / insideConcentration), signed positive for outward cation gradient driving force.
- Osmotic Potential Van't Hoff
Compute osmotic potential in megapascals with the van't Hoff relation as negative i times molal concentration times RT, using R*T = 2.437 MPa*L/mol at 293 K; the van't Hoff factor i defaults to one and may range from one to three.