Texts: This question has already been posted and answered, but I think there's a mistake. Please explain how to do this calculation in detail, i.e., how to calculate current density AND exchange current density. Thank you, will upvote.
(b)
The hydrogen evolution reaction at a Pt electrode yields a current density of 6.7 mA cm^-2 at an overpotential of -0.20 V at 25°C. Estimate the exchange current density, assuming a = 0.5, and comment on the magnitude of this value. [5 Marks]
(c)
The hydrogen evolution reaction at an Hg electrode displays an exchange current density of 2.1 x 10^-13 A cm^-2. Estimate the current density for the HER at an overpotential of -0.20 V at 25°C, assuming a = 0.5, and comment on the magnitude of this value compared to that for Pt. [5 Marks]