Abstract: The chronoampermetry was used to measure the Fe³⁺ diffusion coefficient of 0.031 16 mol/kg of FeCl₃ in the ionic liquid, BPBF₄, at GC working electrode referred to Al/Al³⁺ and at different scan rates over the temperature range from 293.15 to 343.15 K. Since the Fe³⁺ reduction reaction is a reversible process with one transfer electron, according to Cottrell's equation, the values of diffusion coefficient of Fe³⁺ at different temperatures were estimated. As temperature increases, the values of the diffusion coefficient also increase owing to the diminution of the BPBF₄ viscosity. The values of diffusion coefficient were fitted with the method of least-square according to Arrenius' equation, and value of diffusion activation energy of Fe³⁺, E_D=49.5 kJ/mol, was obtained from Arrenius' slope.

Key words: Ionic liquid, Chronoampermetry, Diffusion coefficient, Diffusion activation energy, BPBF4