Semi-xylenol orange is a yellow compound at pH 5.9 but turns red when it reacts with Pb²⁺. A 2.025-mL sample of semixylenol orange at pH 5.9 was titrated with 7.515 × 10^-4 M Pb(NO₃)₂, with the following results:

Make a graph of absorbance versus microliters of Pb²⁺ added. Be sure to correct the absorbances for dilution. Corrected absorbance is what would be observed if the volume were not changed from its initial value of 2.025 mL. Assuming that the reaction of semixylenol orange with Pb²⁺ has a 1:1 stoichiometry, find the molarity of semi-xylenol orange in the original solution.

Transcribed Image Text:

Absorbance Absorbance Total pL Pb2+ added Total μL Pb2+ added at 490-nm at 490-nm wavelength wavelength 0.0 0.227 42.0 0.425 6.0 0.256 48.0 0.445 12.0 0.286 54.0 0.448 18.0 0.316 60.0 0.449 24.0 0.345 70.0 0.450 30.0 0.370 80.0 0.447 36.0 0.399