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What is the corrosion potential of a stainless steel (SS316) electrode in a 0.1 M sodium chloride (NaCl) solution at 25°C if the pH of the solution is 7.2? The standard reduction potential of SS316 is -0.71 V vs. a standard hydrogen electrode (SHE).

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To calculate the corrosion potential of the stainless steel  SS316  electrode in a 0.1 M NaCl solution at 25C and pH 7.2, we need to consider the Nernst equation. The Nernst equation is used to determine the potential of an electrochemical cell under non-standard conditions. The equation is as follows:E = E -  RT/nF  * ln Q where:E = corrosion potential under non-standard conditionsE = standard reduction potential  -0.71 V for SS316 R = gas constant  8.314 J/mol K T = temperature in Kelvin  25C = 298 K n = number of electrons transferred in the redox reaction  for SS316, n = 2 F = Faraday's constant  96485 C/mol Q = reaction quotient, which depends on the concentrations of the species involved in the redox reactionSince the pH of the solution is 7.2, we can calculate the concentration of H+ ions:[H+] = 10^-pH  = 10^-7.2  = 6.31 x 10^-8  MNow, we need to determine the reaction quotient  Q . For the corrosion of SS316 in NaCl solution, the redox reaction can be represented as:SS316 + 2H+ -> SS316 2+  + H2So, the reaction quotient  Q  can be expressed as:Q = [SS316 2+ ] [H2] / [SS316] [H+]^2Since we are interested in the corrosion potential, we can assume that the concentrations of SS316 and SS316 2+  are equal, and the concentration of H2 is constant. Therefore, Q can be simplified to:Q = 1 / [H+]^2Now, we can plug the values into the Nernst equation:E = -0.71 -  8.314 * 298 /  2 * 96485   * ln 1 /  6.31 x 10^-8  ^2 E = -0.71 -  0.0257  * ln 2.52 x 10^15 E  -0.71 - 0.0257 * 34.62E  -1.6 VSo, the corrosion potential of the stainless steel  SS316  electrode in a 0.1 M NaCl solution at 25C and pH 7.2 is approximately -1.6 V vs. a standard hydrogen electrode  SHE .

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