To calculate the corrosion rate of the iron rod, we need to determine the mass loss of iron due to the electrochemical reaction. The reaction taking place is:Fe s Fe aq + 2eThe current I is given as 0.2 A. We can use Faraday's law of electrolysis to determine the mass loss of iron:m = I t M / n F where:m = mass loss of iron g I = current A t = time s M = molar mass of iron g/mol n = number of electrons transferred in the reactionF = Faraday's constant 96485 C/mol We are given the current I = 0.2 A and the number of electrons transferred in the reaction n = 2 . The molar mass of iron M is 55.85 g/mol. However, we need the time t to calculate the mass loss of iron.Since we are asked for the corrosion rate, we can express it as mass loss per unit time g/s . Therefore, we can rewrite the equation as:corrosion rate = I M / n F corrosion rate = 0.2 A 55.85 g/mol / 2 96485 C/mol corrosion rate = 0.000577 g/sNow, we need to convert the corrosion rate from mass loss per unit time to a unit of length, such as mm/year. To do this, we need the density of iron and the surface area A of the iron rod: = 7.87 g/cm density of iron A = 20 cm surface area of the iron rod We can use the following equation to convert the corrosion rate to mm/year:corrosion rate mm/year = corrosion rate g/s 10 mm/cm 1 year / g/cm A cm 3.1536 10 s/year corrosion rate mm/year = 0.000577 g/s 10 mm/cm 1 year / 7.87 g/cm 20 cm 3.1536 10 s/year corrosion rate mm/year 0.184 mm/yearThe corrosion rate of the iron rod is approximately 0.184 mm/year.