Why is it necessary to buffer the solution with sodium acetate in the spectrophotometic determination of iron in FAS (ferrous ammonium sulfate or Mohr's salt)? Be specific. Spectrophotometric Determination of Iron in FASNote: Students will work in pairs, but each will receive a different unknown FASsample. Neither the FAS standard or the FAS unknown samples need to be dried.А.Calibration of SpectrophotometerPrepare the following solutions. (Note: There will be sufficient reagent solutions forboth students to do the complete experiment)a. 0.2 grams of 1,10-orthophenanthroline (monohydrate, monohydrochloride) in200 mL of D.I. water.b. 2.5 g of hydroxylamine hydrochloride in 25 mL of D.I. water.c. 15 g of sodium acetate in 150 mL of D.I. water.Weigh ~ 0.4 grams of P.S. FAS into a clean dry weigh bottle on a pan balance. Then,using the analytical balance, accurately weigh one ~0.1 g sample of FAS primarystandard (ferrous ammonium sulfate; also known as Mohr's salt) into a clean, labeled100 mL volumetric flask. Add about 50 mL of D.I. water and 2 mL of concentratedsulfuric acid (fume hood), and then dilute to the mark with D.I. water and shakethoroughly. Record the concentration of this stock solution in your notebook as gramsof FASper mL of solution (g/mL).Rinse a, clean, and dry 100 mL beaker three times with the stock solution preparedabove, and then transfer the remaining stock solution out of the volumetric flask into therinsed beaker. Next rinse the pipette tip three times with 5 mL's of the stock solutionbefore pipetting the following aliquots.Prepare a series of calibration standards that have increasing concentrations of FAS bypipetting increasing volumes of the stock solution (1.0, 2.0, 3.0, 4.0, and 5.0 mL aliquots,respectively) into five clean 100 mL volumetric flasks. Next add 1 mL of thehydroxylamine hydrochloride solution, 10 mL of 1,10-orthophenanthroline, and 8 mL ofthe sodium acetate solution to each flask. Dilute to the mark with D.I. water, shakethoroughly, and allow these solutions to stand (capped) for 10 minutes.Prepare the Vernier spectrophotometer by allowing it to warm up and then running asolvent blank of D. I. water. For each FAS solution, measure the percent transmission(%T) at 508 nm. Keep the wavelength constant for each measurement. You canconvert %T to absorbance using A=2- log (%T).%3D

To explain the reason of buffering the solution with sodium acetate in the spectrophotometric determination of iron in FAS (ferrous ammonium sulfate or Mohr's salt)Sodium acetate along with sulphuric acid already present helps in maintaining the pH of the buffer around 4.5-5. In this acidic environment, oxidation of iron (Fe2+) species is inhibited which can otherwise occur in a neutral solution. When hydroxylamine is added, it acts as a reducing agent and converts all Fe3+ species to Fe2+ forming a complex. This complex formation is pH dependent and hence the buffer helps in preserving the species.