prbset11_key4324

# prbset11_key4324 - EMA 4324 Problem Set 11 6-5 Equal 1-cm2...

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EMA 4324 Problem Set 11 6-5. Equal 1-cm 2 areas of metals P and Q are immersed together in sulfuric acid of unit H + activity having no other dissolved oxidizers. Using the electrochemical parameters listed below: [a] Determine corrosion potential and corrosion rate for each, when they are uncoupled; **************************************************** log[i corr ] = {[E C -E A ]+ β A log[i o (A)]+ β C log[i o (C)]}/[ β A + β C ] for [P], log[i corr ] = {[0-(-0.5)]+0.1log[3x10 -7 ]+0.1log[10 -6 ]}/[0.1+0.1] = -3.76; i corr (P) =1.73x10 -4 A E corr = E A + β A log[i corr /i o (A)] = -0.5 + 0.1log[1.73x10 -4 /3x10 -7 ] E corr (P) = -0.223 V for [Q], log[i corr ] = {[0-(-0.6)]+0.1log[2x10 -6 ]+0.1log[10 -5 ]}/[0.1+0.1] = -2.35; i corr (Q) =4.47x10 -3 A E corr = -0.6 + 0.1log[4.47x10 -3 /2x10 -6 ]; E corr (Q) = -0.265 [b] When P and Q are electrically coupled, determine the potential and current passing in the galvanic couple so formed; **************************************************** Assume i o (C) = 10 -5 +10 -6 = 1.1x10 -5

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## This note was uploaded on 10/18/2011 for the course EMA 4324 taught by Professor Staff during the Fall '09 term at University of Florida.

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prbset11_key4324 - EMA 4324 Problem Set 11 6-5 Equal 1-cm2...

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