Why is it necessary to carry out the reduction of iron and then the titration, before goin on to the next sample? ProcedureWeigh four (4) 0.3 g sample of the dried unknown into four 400 or 600 mL beakers.Add 50 mL of 6 M HCI to each sample beaker and heat in the fume hood until the solutions boil for 30 seconds or until the sample dissolvesObtain approximately 20 mL of stannous chloride solution (SnCl2) from the reagent hoodAdd SnCl2 to the hot unknown solution drop-wise with a disposable plastic pipet until the solution changes from yellow to light greenAdd three drops of SnCl2 solution in excessRemove the sample from the fume hood and cool the solution to room temperature (a room temperature tap water bath is OK but no ice)After cooling, rapidly add 10 mL of the saturated HgClh solution (obtained from the reagent hood). Allow the sample solution to stand for 3 minutes – a precipitate should formTo the sample solution add 60 mL of 3 M H2SO4, 15 mL of 85% H3PO4 and 100 mL of D.I. water. Allow the solution cool briefly (two minutes), then add 8 drops of diphenylamine sulfonate indicator.Titrate immediately with the dichromate solution to violet-blue endpoint. Repeat with other samples

The objective of this question is to determination of iron in a sample through a redox titration.The…

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Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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Why is it necessary to carry out the reduction of iron and then the titration, before goin on to the next sample?

Procedure

Weigh four (4) 0.3 g sample of the dried unknown into four 400 or 600 mL beakers.
Add 50 mL of 6 M HCI to each sample beaker and heat in the fume hood until the solutions boil for 30 seconds or until the sample dissolves
Obtain approximately 20 mL of stannous chloride solution (SnCl₂) from the reagent hood
Add SnCl₂ to the hot unknown solution drop-wise with a disposable plastic pipet until the solution changes from yellow to light green
Add three drops of SnCl₂ solution in excess
Remove the sample from the fume hood and cool the solution to room temperature (a room temperature tap water bath is OK but no ice)
After cooling, rapidly add 10 mL of the saturated HgClh solution (obtained from the reagent hood). Allow the sample solution to stand for 3 minutes – a precipitate should form
To the sample solution add 60 mL of 3 M H₂SO₄, 15 mL of 85% H3PO4 and 100 mL of D.I. water. Allow the solution cool briefly (two minutes), then add 8 drops of diphenylamine sulfonate indicator.
Titrate immediately with the dichromate solution to violet-blue endpoint.
Repeat with other samples

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