Calamine, which is used for relief of skin irritations, is a mixture of zinc and iron oxides. A 1.022-g sample of dried calamine was dissolved in acid and diluted to 250.0 mL. A 50.00 mL aliquot was suitably buffered and titrated with 2.40 mL of 0.002727 M ZnY-2 (Zn-EDTA) solution to allow the following reaction: Fe+3 + ZnY-2 → FeY- + Zn+2. Molecular mass: Fe2O3 = 165.74 a. The weight of sample in the aliquot portion is _________g ? b. the percentage composition of Fe2O3 in the sample is ______ % ?

Calamine, which is used for relief of skin irritations, is a mixture of zinc and iron oxides. A 1.022-g sample of dried calamine was dissolved in acid and diluted to 250.0 mL. A 50.00 mL aliquot was suitably buffered and titrated with 2.40 mL of 0.002727 M ZnY-2 (Zn-EDTA) solution to allow the following reaction: Fe+3 + ZnY-2 → FeY- + Zn+2. Molecular mass: Fe2O3 = 165.74 a. The weight of sample in the aliquot portion is ___g ? b. the percentage composition of Fe2O3 in the sample is % ?

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter17: Complexation And Precipitation Reactions And Titrations

Section: Chapter Questions

Problem 17.33QAP

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Titration of 25.0 mL of a 0.0500 M Zn2+ solution with 0.0550 M EDTA in a solution buffered at pH 8. Assume that the temperature is 25 oC and that the formation constant for Zn2+ is 3.13 x 1016 at this temperature. What is the pZn of the solution after 30 mL of titrant have been added?
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Titration of 25.0 mL of a 0.0500 M Zn2+ solution with 0.0550 M EDTA in a solution buffered at pH 8. Assume that the temperature is 25 oC and that the formation constant for Zn2+ is 3.13 x 1016 at this temperature. What is the pZn at the equivalence point of the titration?
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