Вопрос
- Plain carbon steel immersed in seawater has a uniform corrosion rate expressed as a penetration rate of 0,127 sm/year .The density of iron is 7.87g/cm^3 The atomic weight of Fe is 55.8g/mol - (a) Calculate the weight loss after 1 year. (b) Calculate the corresponding corrosior current density in microamperes per square centimeter, assuming that the corrosion given by Fearrow Fe^2++2e^-
Решения
4.7
(199 Голоса)
Юрий
ветеран · Репетитор 11 лет
Ответ
(a) To calculate the weight loss after 1 year, we need to first determine the volume of iron corroded per year. The penetration rate is given as 0.127 sm/year, which means that the depth of corrosion increases by 0.127 sm (square millimeters) per year.The volume of iron corroded per year can be calculated using the formula:Volume = Penetration rate × AreaSince the penetration rate is given in sm/year, we need to convert it to cm/year by multiplying it by 0.1 (1 sm = 0.1 cm).Volume = 0.0127 cm/year × AreaNow, we can calculate the weight loss by multiplying the volume of iron corroded per year by the density of iron and the atomic weight of Fe.Weight loss = Volume × Density × Atomic weightWeight loss = (0.0127 cm/year × Area) × 7.87 g/cm³ × 55.8 g/molWeight loss = 0.0045 g/year × AreaTherefore, the weight loss after 1 year is 0.0045 g/year × Area.(b) To calculate the corresponding corrosion current density in microamperes per square centimeter, we need to use Faraday's law of electrolysis. According to Faraday's law, the amount of substance liberated at an electrode during electrolysis is directly proportional to the amount of electricity passed through the electrolyte.The corrosion reaction given is Fe → Fe²⁺ + 2e⁻, which means that for every iron atom corroded, 2 electrons are released. Therefore, the number of moles of electrons released per year can be calculated using the formula:Moles of electrons = Weight loss × Atomic weight / (Molar mass of Fe × 2)Now, we can calculate the corrosion current density using the formula:Corrosion current density = Moles of electrons × Faraday's constant / (Area × Time)Faraday's constant is 96485 C/mol, which represents the charge of 1 mol of electrons.Corrosion current density = (Weight loss × Atomic weight / (Molar mass of Fe × 2)) × 96485 / (Area × Time)Since the weight loss is given in g/year, we need to convert it to C/year by multiplying it by the atomic weight of Fe and dividing it by the molar mass of Fe.Corrosion current density = (Weight loss × Atomic weight / (Molar mass of Fe × 2)) × 96485 / (Area × Time)Corrosion current density = (0.0045 g/year × 55.8 g/mol / (55.8 g/mol × 2)) × 96485 / (Area × Time)Corrosion current density = 0.0127 A/cm²Therefore, the corresponding corrosion current density is 0.0127 A/cm².