Debye huckel
The theory developed by Debye-huckel is for dilute solution of electrolyte.
Thus Arrhenius theory although valid for weak electrolyte thus not represent true
solution of strong electrolyte. There for there was a need to construct a theory
which can explain the behavior of strong electrolyte.
According to Debye-huckel
The dilute solution of strong electrolyte are completely ionized. The properties
of the solutions are due to unequal distribution of ions resulting in inter ionic interaction.
They showed that because of the electrostatic attraction between charged ions each positive
ions in the solution is surrounded by more negative ions and vice versa. In other words each ion in solution is surrounded by an ionic atmosphere whose net charge is opposite to the charge of the central ion.
The properties of electrolyte are described by the interaction of the central ion and its atmosphere . Since the nature of the atom is decided by the valance of ion, concentration of the electrolyte ,
Temperature and Dielectric constant of the medium.
These are also the properties controlling thermodynamic behavior of the solution.
The distribution of opposite ion around the central ion is spherically symmetrical. This kind of
distribution exists in the absence of electric field. This unequal distribution of ions is responsible for Electrostatic interaction. This aspects of existence of this kind of distribution of ions in electrolyte is a basis for the theory developed by Debye-Huckel.
Electrostatic interaction depends on - 1) Concentration of electrolyte. 2) Temperature 3) Dielectric constant 4) Valance of Ion.
For a given electrolyte taken in a solvent at a given temperature , the inter ionic interactions should
be depends on concentration of electrolyte. Concentration is not same for all electrolyte. When we are dealing
with electrolyte we have to consider the factors like dissociation of number of particles and the charge
associated with the ion. Such concentration of ions is called Ionic Strength. Ionic strength is the true measure of the character of ion. Debye-Huckel proposed thet there are inter ionic interaction. It is an important feature of Debye- Huckel Theory.
