9) Cr³+ reacts slowly with EDTA (Y4-) so it is usually analyzed using back-titration. A 100.0 mL treated water sample containing only Cr³+ was diluted to 1 L and 25.0 mL 0.005 M Y4- was added to a 10 mL aliquot of the diluted sample. The excess Y4- required 23.0 mL 0.005 M CaCl2 to reach the EBT end-point. Find the ppm Cr³+ in the water sample. a.) 5.2 ppm b.) 52 ppm c.) 520 ppm d.) 5200 ppm

9) Cr³+ reacts slowly with EDTA (Y4-) so it is usually analyzed using back-titration. A 100.0 mL treated water sample containing only Cr³+ was diluted to 1 L and 25.0 mL 0.005 M Y4- was added to a 10 mL aliquot of the diluted sample. The excess Y4- required 23.0 mL 0.005 M CaCl2 to reach the EBT end-point. Find the ppm Cr³+ in the water sample. a.) 5.2 ppm b.) 52 ppm c.) 520 ppm d.) 5200 ppm

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter14: Applications Of Ultraviolet-visible Molecular Absorption Spectrometry

Section: Chapter Questions

Problem 14.6QAP: The accompanying data (1.00-cm cells) were obtained for the spectrophotometric titration 10.00 mL of...

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A 500.0mg of butter was warmed and shaken vigorously with water. The undissolved material was removed by filtering and the aqueous portion was made 1.0M in HNO3 and 0.025M in Fe(NO3)3. This acidified solution was treated with 10.00ml of 0.1755M AgNO3 to precipitate the chloride ion and, after the addition of a small amount of nitrobenzene, 14.22ml of 0.1006M KSCN was required to back titrated the excess Ag+. Calculate the % NaCl in the butter.
A 50.00 ml aliquot of a solution containing Ca2+ and Mg2+ was buffered at pH 10 and titrated with 0.0421 M EDTA. The endpoint volume was 44.10 ml. A second aliquot of the same mixture was made strongly basic by the addition of NaOH – this causes the Mg2+ to precipitate as Mg(OH)2. The solution was then titrated with the 0.0421 M EDTA and the endpoint volume was found to be 35.11 ml.
A 50.00 ml aliquot of a solution containing Ca2+ and Mg2+ was buffered at pH 10 and titrated with 0.0418 M EDTA. The endpoint volume was 44.36 ml. A second aliquot of the same mixture was made strongly basic by the addition of NaOH – this causes the Mg2+ to precipitate as Mg(OH)2. The solution was then titrated with the 0.0418 M EDTA and the endpoint volume was found to be 30.02 ml. Calculate the molar concentration of Mg.
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A 0.3045 g of CaCO3 primary standard was dissolved using concentrated HCl, evaporated to incipient dryness and quantitatively transferred to a 250 mL volumetric flask, and diluted to mark. A 10 mL of aliquot was then transferred to an Erlenmeyer flask, together with 5mL buffer and 5 drops of EBT indicator, and was used to standardize the EDTA titrant. The solution turned blue after the addition of 24.10 mL of EDTA. A blank correction was performed and was determined to be 0.4 mL. What is the concentration of EDTA obtained (MW CaCO3 = 100.0869 g/mol)?
A 10.0 mL sample containing Fe³⁺ and Cu²⁺ was diluted to 100.0 mL solution. A 20.0 ml aliquot required 25.0 ml of 0.0500 M EDTA for complete titration. A separate 20.0 ml aliquot of the diluted sample was treated with NH₄F to protect the Fe³⁺. Then the Cu²⁺ was treated with thiourea. Upon addition of 25.0 mL of 0.0500 M EDTA, the Fe³⁺ was liberated from its fluoride complex and formed an EDTA complex. The excess EDTA required 21.5 mL of 0.0180 M Pb²⁺ to reach an end point, using xylenol orange. (a) Identify the masking agent. (b) Identify the auxiliary complexing agent. (c) Calculate the molar concentration of the Fe³⁺ in the original sample. (d) Calculate the molar concentration of the Cu²⁺ in the original sample
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