Which is CORRECT? a. EDTA has 2 oxygen sites and 2 nitrogen sites that are electron rich. b. At pH = 10, fraction of fully deprotonated form of EDTA approaches to 1. c. EDTA titrations that are carried out beyond pH 10 typically involves the use of auxiliary reagents. d. As long as EDTA titrations are carried out beyond pH 10, we are sure that all of the analyte will react completely with EDTA.

Which is CORRECT? a. EDTA has 2 oxygen sites and 2 nitrogen sites that are electron rich. b. At pH = 10, fraction of fully deprotonated form of EDTA approaches to 1. c. EDTA titrations that are carried out beyond pH 10 typically involves the use of auxiliary reagents. d. As long as EDTA titrations are carried out beyond pH 10, we are sure that all of the analyte will react completely with EDTA.

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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b. EDTA cannot be used as a primary standard always. When can EDTA be used as a primarystandard ? Give reason why EDTA is used in complexometric titrations.
Using the reagents, prepare 100mL solution with a concentration of 25.0 mM Tris buffer at a final pH of 7.70. •Solid Tris, FW = 121.1• Solid Tris-C1, the conjugate acid of Tris. It has a pKa of 8.30 (at 25° C) and a FW of 157.6. •deionized water
a. What is the structure and full name for EDTA? b. The titration of Zn^+2 and EDTA is carried out in the same manner as the Mg^+2 * EDTA titration (in fact, Zn metal may be used to standardize your EDTA solution). In this case, the ammonia from the pH 10 buffer serves an additional purpose. What is it? c. Although EDTA has, in its fully protonated form, 4 hydrogen atoms that can be lost, it is listed as a hexadentate ligand. Explain why this is the case.
A deepwell water sample of 100 mL was titrated with 0.010 M EDTA at pH 12 and consumed 31 mL. Calculate the Calcium content of the water sample in mg/L. Ans in 3 sig figures. no need to write the unit.
1. Why is it necessary to use a buret for measuring standard AgNO3 solution in volhard method? 2. What is the effect of discolored AgNO3 on the concentration of KSCN? 3. Why is necessary to use boiled 6N HNO3 in volhard? 4. why is the titration done with vigorous swirling?
A 30-mL portion of a solution containing Ca2+ and Mg2+ was titrated with 28.19 mL of 0.213 M EDTA at pH 10. Another 30-mL aliquot of the same Ca-Mg mixture was treated with NaOH to make the solution strongly alkaline and precipitate Mg(OH)2. This solution was then titrated with the same EDTA solution. What would be the required EDTA volume (in mL) to reach the endpoint of the second aliquot if it was found that there was 0.061 M of Mg2+ in the sample?
Write the involved chemical reactions for this: An EDTA solution was prepared by dissolving approximately 4 g of the disodium salt in approximately 1Lof water. An average of 42.35 mL of this solution was required to titrate 50.00-mL aliquots of a standard that contained 0.7682 g of MgCO3 per liter. Titration of a 25.00-mL sample of mineral water at pH 10 required 18.81 mL of the EDTA solution. A 50.00-mL aliquot of the mineral water was rendered strongly alkaline to precipitate the magnesium at Mg(OH)2. Titration with a calcium-specific indicator required 31.54 mL of the EDTA solution. Calculate (a) the molar concentration of the EDTA solution, (b) the concentration of CaCO3 in the mineral water in ppm, (c) the concentration of MgCO3 in the mineral water in ppm.
A 50.0-mL sample containing Ni2+ was treated with 25.0 mL of 0.0500 M EDTA to complex all the Ni2+ and leave excess EDTA in solution. The excess EDTA was then back-titrated, requiring 5.00 mL of 0.0500 M Zn2+. What was the molar concentration of Ni2+ in the original solution?
Cd²+ forms a stable complex with EDTA. Consider the titration of 30.00 ml of 0.0525 M Cd with 0.125 M EDTA at pH 9, using Eriochrome black T as the indicator. Constants you may need: log K, (Cd-EDTA) 16.5. a, @ph 9= 0.052 The pCd at equivalence point (12.6 mL) is [a]
A 25.00 mL sample containing Fe3+ was treated with 10.00 mL of 0.03676 M EDTA to complex all the Fe3+ and leave excess EDTA in solution. The excess EDTA was then back-titrated, requiring 2.37 mL of 0.04615 M Mg2+. What was the concentration of Fe3+ in the original solution in ppm Fe3+?
Elaborate the reason why EDTA is used in many complexometric titrations. How will you be able to improve its selectivity when it comes to analyzing specific metals?