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prbset064324

# prbset064324 - 2 of the metal M in an acid solution of unit...

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EMA 4324 Problem Set 6 6-1 [Jones 3-6] Using appropriate polarization [Evans] diagrams, determine the effect of the following parameters on the corrosion potential and corrosion rate [CPR] of metal M corroding to M + in an acid solution: [a] increasing j o of the anodic reaction; [b] increasing j o of the cathodic reaction; [[c] increasing the concentration of dissolved H + ; and [d] increasing the Tafel constant for the anodic reaction. 6-2 [Jones 3-8] [a] Plot the appropriate polarization curves for the following “half-cell” reactions and determine the corrosion potential and corrosion rate [CPR, current density] assuming activation control of both the anodic and cathodic processes. [b] Same as [a], but assume the limiting current density for the reduction reaction is 10-5 A/cm 2 . Again, determone the corrosion potential and corrosion rate [CPR, current density] from your plot. 6-3 [Jones 3-10] Plot the polarization data shown below for an electrode of 1.13 cm
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Unformatted text preview: 2 of the metal M in an acid solution of unit activity bubbled with pure hydrogen [unit pressure]. How might the potentials be measured experimentally? From your plot [data, not cemetery], determine the corrosion rate [A/cm 2 ] and the exchange current density for the hydrogen reduction reaction on the surface of metal M. Comment on the accuracy of your determinations. 0.1 10-6 0.10 2H + + 2e-= H 2 0.1 10-8-0.70 M +1 + 1e-= M b , V j o , A/cm 2 E Nernst , V SHE reaction My sign convention will result in a positive value for b since I define h in such a way that it is always positive. Otherwise, b can be negative with a negative overpotential for a process. ...-0.5663-5x10-3-0.7375-1x10-1-0.5287-2x10-3-0.7117-5x10-2-0.5075-1x10-3-0.6425-2x10-2-0.4939-5x10-4-0.6267-1x10-2-0.4843-2x10-4 Potential, V SHE Current, A Potential, V SHE Current, A...
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