Ilkovic equation in Polarography
The Ilkovic equation is used in polarography analysis to determine the diffusion coefficient of an electroactive species in solution. The equation is named after the Slovakian chemist Frantisek Ilkovic, who developed it in the 1930s.
The Ilkovic equation relates the current density (i) to the concentration of the electroactive species (C), the diffusion coefficient of the species (D), the electrode surface area (A), the electron charge (F), and the diffusion layer thickness (delta):
i = (FACD)/delta
i = current density (A/cm2) C = concentration of electroactive species (mol/cm3) D = diffusion coefficient of the species (cm2/s) A = electrode surface area (cm2) F = Faraday’s constant (96485 C/mol) delta = diffusion layer thickness (cm)
The Ilkovic equation assumes that the electroactive species is present in a homogeneous solution, and that the concentration and diffusion coefficient are constant throughout the solution. The equation also assumes that the electrode is planar and that the diffusion layer thickness is much smaller than the electrode size.
By measuring the current density at different concentrations of the electroactive species, the diffusion coefficient can be calculated using the Ilkovic equation. This information can then be used to determine other important electrochemical parameters, such as the rate of reaction and the kinetic parameters of the electrochemical process.
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