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Calculate the anodic Tafel slope for a reaction with an exchange current density of 2x10^-4 A cm^-2 if the current density at an anodic potential of 0.1V vs the standard hydrogen electrode (SHE) is 0.5 mA cm^-2 and at 0.2V vs SHE is 2.0 mA cm^-2. Assume a linear relationship between current density and overpotential.

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To calculate the anodic Tafel slope, we can use the Tafel equation: = b * log i / i where  is the overpotential, b is the Tafel slope, i is the current density, and i is the exchange current density.We are given two sets of data points:  , i  and  , i . The overpotential  can be calculated as the difference between the applied potential and the equilibrium potential  E - E . Since we are given the anodic potential with respect to the standard hydrogen electrode  SHE , we can assume that the equilibrium potential E is 0 V. Therefore, the overpotentials are  = 0.1 V and  = 0.2 V.The current densities i and i are given as 0.5 mA cm and 2.0 mA cm, respectively. We need to convert them to A cm:i = 0.5 mA cm *  1 A / 1000 mA  = 5 * 10 A cmi = 2.0 mA cm *  1 A / 1000 mA  = 2 * 10 A cmNow we can use the Tafel equation to set up a system of two equations with two unknowns  b and i : = b * log i / i  => 0.1 = b * log 5 * 10 / i  = b * log i / i  => 0.2 = b * log 2 * 10 / i We are given the exchange current density i = 2 * 10 A cm. We can now solve for b:0.1 = b * log 5 * 10 /  2 * 10  0.1 = b * log 2.5 To find b, we can isolate it by dividing both sides by log 2.5 :b = 0.1 / log 2.5 Now we can calculate the value of b:b  0.1 / 0.3979b  0.251 V/decadeThe anodic Tafel slope for the given reaction is approximately 0.251 V/decade.

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