(a) Butler-volmer equation and redox system question

The Butler-Volmer equation for a one electron transfer is given by:

When the over potential is so small that F?/RT

The exchange current density of a electrode at 298 K is 0.79 mA cm ^-2 . using equation 1 , assume the overpotential is +5.0 mV and RT/F = 25.7 mV at 298K and:

(i) Calculate the current density

(ii) Calculate the current going through an electrode Of a total area Of 5 cm ²

(b) Consider a hypothetical one-electron redox system, M ²⁺ M ³⁺ . Assume that [M ²⁺ l > [M ³⁺ ] and that the rate of diffusion is the same for M ²⁺ and M ³⁺

(i) Draw a labeled sketch plot of the current density versus overpotential, clearly labeling the oxidation/reduction regions and the charge transfer and mass transfer control regions. (ii) Show how the plot under (i) is expected to change if the temperature increases.

Transcribed Image Text:

anFn = io [exp (CRP) - ex exp RT inet = io 1-a)nFn) RT inet lo Fn RT Equation 1 anFn = io [exp (CRP) - ex exp RT inet = io 1-a)nFn) RT inet lo Fn RT Equation 1

Answer rating: 100% (QA)

Given that Butlervolumer equation for a one electron transfer i net i exp nF RT ... View the full answer