To calculate the corrosion rate, we need to determine the loss of mass per unit area per unit time. First, let's find the surface area of the copper wire.1. Calculate the volume of the lost copper mass:Copper has a density of 8.96 g/cm. To find the volume, we can use the formula:Volume = Mass / DensityVolume = 3 g / 8.96 g/cm 0.335 cm2. Calculate the surface area of the corroded copper:Since the wire is 5mm thick, we can assume it has a cylindrical shape. The corroded volume can be considered as a thin layer removed from the surface of the cylinder. The volume of a cylinder is given by:Volume = * r * hWhere r is the radius and h is the height length of the cylinder. We can rewrite the formula to find the height length of the corroded layer:h = Volume / * r Let r1 be the initial radius and r2 be the final radius after corrosion. The corroded volume can be represented as the difference between the volumes of two cylinders:0.335 cm = * r1 * h - r2 * h Since the thickness of the wire is 5mm 0.5 cm , we can write:r1 - r2 = 0.5 cmNow, we have two equations and two unknowns r1 and h . We can solve for r1 and h using these equations:0.335 cm = * r1 * h - r1 - 0.5 * h r1 - r2 = 0.5 cmSolving these equations, we get:r1 0.292 cmh 2.45 cm3. Calculate the surface area of the corroded copper:The surface area of a cylinder is given by:Surface Area = 2 * * r * hUsing the final radius r2 = r1 - 0.5 and the height h we found:Surface Area 2 * * 0.292 cm * 2.45 cm 4.49 cm4. Calculate the corrosion rate:Now that we have the surface area, we can calculate the corrosion rate as the mass loss per unit area per unit time:Corrosion Rate = Mass Loss / Surface Area * Time Corrosion Rate = 3 g / 4.49 cm * 10 days 0.067 g/cm/dayThe corrosion rate of the 5mm thick copper wire exposed to a 20% NaCl solution at 25C is approximately 0.067 g/cm/day.