To determine the concentration of iron Fe in a given water sample using spectrophotometry, you will need to follow these steps:1. Prepare a series of standard solutions: Prepare a series of standard solutions with known concentrations of iron Fe by diluting a stock solution of iron. These standard solutions will be used to create a calibration curve.2. Create a calibration curve: Measure the absorbance of each standard solution at the specific wavelength where iron absorbs light usually around 510 nm using a spectrophotometer. Plot the absorbance values y-axis against the corresponding iron concentrations x-axis to create a calibration curve.3. Prepare the water sample: Filter the water sample to remove any suspended particles or impurities that may interfere with the spectrophotometric analysis. If necessary, acidify the sample with a small amount of concentrated nitric acid HNO3 to dissolve any precipitated iron.4. Treat the water sample with a colorimetric reagent: Add a colorimetric reagent, such as 1,10-phenanthroline, to the water sample. This reagent will form a colored complex with iron, which can be detected by the spectrophotometer.5. Measure the absorbance of the water sample: Measure the absorbance of the treated water sample at the same wavelength used for the standard solutions around 510 nm .6. Determine the concentration of iron in the water sample: Using the calibration curve, find the concentration of iron Fe that corresponds to the measured absorbance value of the water sample. This will give you the concentration of iron in the water sample.Note: The accuracy of the results depends on the quality of the standard solutions, the calibration curve, and the proper handling of the water sample. Make sure to follow good laboratory practices and use appropriate equipment to ensure accurate results.