To determine the concentration of iron Fe in a sample of water collected from a nearby river using spectrophotometric analysis, you will need to follow these steps:1. Collect a water sample from the river.2. Prepare a series of iron standard solutions with known concentrations, typically ranging from 0 to 1 mg/L or any suitable range depending on the expected concentration of iron in the water sample .3. Treat the water sample and the iron standard solutions with a suitable reagent that forms a colored complex with iron. A common reagent for this purpose is 1,10-phenanthroline, which forms an orange-red complex with iron II .4. Measure the absorbance of the treated water sample and the iron standard solutions at the wavelength of maximum absorbance usually around 510 nm using a spectrophotometer.5. Plot a calibration curve by graphing the absorbance values of the iron standard solutions against their known concentrations. The calibration curve should be a straight line with a linear regression equation in the form of y = mx + b, where y is the absorbance, x is the concentration, m is the slope, and b is the y-intercept.6. Determine the absorbance of the treated water sample and use the calibration curve to find the corresponding concentration of iron in the sample. Substitute the absorbance value y into the linear regression equation and solve for x the concentration of iron .For example, if the linear regression equation is y = 0.5x + 0.01 and the absorbance of the treated water sample is 0.25, you can calculate the concentration of iron as follows:0.25 = 0.5x + 0.010.24 = 0.5xx = 0.48 mg/LSo, the concentration of iron in the water sample is 0.48 mg/L.Keep in mind that this is a simplified explanation of the process, and actual laboratory procedures may vary depending on the specific equipment and reagents used. Additionally, it's important to follow proper safety protocols and guidelines when working with chemicals and laboratory equipment.