Question 4: A potential step experiment was carried out in a solution containing 0.05M ferrocyanide ([Fe(CN)6]4-) dissolved in a solution containing a large excess of inert electrolyte. Care was taken to ensure that there was no stirring of the solution during the experiment, which means that the mass transport resistance was entirely due to diffusion. The potential was stepped from a value where there was no reaction to a potential at which the [Fe(CN)6]4- was completely oxidised to [Fe(CN)6]3- at a Diffusion-controlled rate, and the following currents were recorded: T/s 0.1, 0.2, 0.4, 0.8, and 1.2 I/mA 6.9, 4.9, 3.4, 2.4, 2.0 1) Make a sketch of a concentration profile of [Fe(CN)6]4- as a function of distance away from the electrode, time = 0, and 2-3 other times within the range of the experiment. How will the profiles look at 2 different diffusivities (You need 2 graphical sketches)? 2) Given that the area of the electrode is 0.3 cm2, calculate the diffusion coefficient of [Fe(CN)6]4- in the solution.