Determine the known variables: Boltzmann constant, electronic charge of an ion, Avogadro's number and the permittivity of vacuum are known variables. The values of these variables are always constant:
k= 1.38*10^-23m^2kgs^-2K^-1
e=1.6022*10^-19 Columb
No= 6.023*10^23
Eo= 8.854*10^-12(F/m)
Determine unknown variables: Though temperature (T) of the solution is usually given, it should always be converted into absolute scale. The absolute temperature is measured in terms of Kelvin.
Determine the ionic charge of the solution: The ionic charge of the solution is the sum of the individual ions present in the solution. It can be represented by:
Ionic charge= Sum.cz *e^2, where cz is individual ions and e is the electronic charge
(1.6022*10^-19 Columb).
Determine the dielectric constant of the materials: The dielectric constant is unique to every material or solution. For a particular material used, the value will usually be given. It is the ratio of electric field produced without dielectric to the field with dielectric.
Dielectric acts as an insulator when it is placed in an electric field.
Determine Kappa: Kappa or the Dybye-Huckel parameter is determined by using this equation:
Kappa= 1/(sqrt(Eo*Ep*k*T)/(2000*No*Sum.cz*e^2)), where means the square root.
After determining Kappa, Debye length can be calculated by taking the reciprocal (1/K) of the Kappa.
Lamda = 1/Kappa
The unit of Kappa is inverse meter and the unit of Debye length is meter.