To calculate the anodic Tafel slope a for the oxidation of iron in a solution with a pH of 3, we can use the Tafel equation: = a * log i / i where: = overpotential 0.2 V i = corrosion current density 2.5 x 10^-6 A/cm i = exchange current density unknown a = anodic Tafel slope unknown First, we need to find the exchange current density i . The exchange current density can be estimated using the Butler-Volmer equation:i = i * exp a * F * / R / T - exp -c * F * / R / T where:a = anodic charge transfer coefficient assumed to be 0.5 c = cathodic charge transfer coefficient assumed to be 0.5 F = Faraday's constant 96485 C/mol R = gas constant 8.314 J/mol K T = temperature assumed to be 298 K, room temperature Since we are only interested in the anodic reaction, we can simplify the equation to:i = i * exp a * F * / R / T Now, we can solve for i:i = i / exp a * F * / R / T Plugging in the values:i = 2.5 x 10^-6 A/cm / exp 0.5 * 96485 C/mol * 0.2 V / 8.314 J/mol K * 298 K i 1.16 x 10^-6 A/cmNow that we have the exchange current density, we can use the Tafel equation to find the anodic Tafel slope a :0.2 V = a * log 2.5 x 10^-6 A/cm / 1.16 x 10^-6 A/cm a = 0.2 V / log 2.5 x 10^-6 A/cm / 1.16 x 10^-6 A/cm a 0.2 V / 0.434a 0.460 V/decadeThe anodic Tafel slope for the oxidation of iron in a solution with a pH of 3 is approximately 0.460 V/decade.