Debye Length - Debye Length in An Electrolyte

Debye Length in An Electrolyte

In an electrolyte or a colloidal suspension, the Debye length is usually denoted with symbol κ−1

where

I is the ionic strength of the electrolyte, and here the unit should be mole/m3,

ε₀ is the permittivity of free space,

ε_r is the dielectric constant,

k_B is the Boltzmann constant,

T is the absolute temperature in kelvins,

N_A is the Avogadro number.

e is the elementary charge,

or, for a symmetric monovalent electrolyte,

where

R is the gas constant,

F is the Faraday constant,

C₀ is the molar concentration of the electrolyte.

Alternatively,

where

is the Bjerrum length of the medium.

For water at room temperature, λ_B ≈ 0.7 nm.

At room temperature (25 °C), one can consider in water the relation :

where

κ−1 is expressed in nanometers (nm)

I is the ionic strength expressed in molar (M or mol/L)