Which statement about an auxiliary complexing agent is TRUE? O It forms a complex with the metal ion. O It forms a complex with the indicator. O It protects some components in the mixture from reacting with EDTA. OIt increases the conditional formation constant. O It displaces the metal ion from the metal-EDTA complex. A 25.00-mL solution of NaOH was used to titrate 0.786 4 g potassium hydrogen phthalate (KHP, FM 204.2) according to the following reaction. What is the concentration of the NaOH solution? .COOK .COOK NaOH H2O COOH COONA O 0.154 2 M O6.423 M 0.003 855 M O1.542 x 10-2 M O1.542 x 10-4 M

Which statement about an auxiliary complexing agent is TRUE? O It forms a complex with the metal ion. O It forms a complex with the indicator. O It protects some components in the mixture from reacting with EDTA. OIt increases the conditional formation constant. O It displaces the metal ion from the metal-EDTA complex. A 25.00-mL solution of NaOH was used to titrate 0.786 4 g potassium hydrogen phthalate (KHP, FM 204.2) according to the following reaction. What is the concentration of the NaOH solution? .COOK .COOK NaOH H2O COOH COONA O 0.154 2 M O6.423 M 0.003 855 M O1.542 x 10-2 M O1.542 x 10-4 M

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter9: Complexometric And Precipitation Titrations

Section: Chapter Questions

Problem 8P

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In complexation volumetry, classify the statements below as true or false.Justify the one(s) that you judge to be “false”.a) When preparing an EDTA solution, to be used as a titrant of Ca2+ ions, it is necessary to add a small amount of Mg2+ in the solution.b) A metallochromic (Ind) indicator is a substance that forms colored complexes with metallic ions. The colors of these complexes are always the same as the colors of the free forms of these indicators.c) In order for the titration of a metal (Me) with EDTA to be carried out, it is necessary that the Me-EDTA complex has a stability constant greater than that of the Me-Ind complex.d) In determining the partial hardness of a hard water sample with EDTA solution, murexide is used as an indicator at pH 10.
The brine solution has a significant amount of chloride, and it is determined by the Volhard method. A 10.0-aliquot of the solution is treated with 15.25 mL of standard 0.1163 M AgNO3 solution. The excess silver is titrated with standard 0.101 M KSCN solution, requiring 3.28 mL to reach the red Fe(SCN)2+ end point. Calculate the concentration of chloride in the brine solution in mg/L and g/L.
The titration of Zn+2 and EDTA is carried out in the same manner as the Mg+2-EDTA titration. In this case, the ammonia in the EDTA buffer serves an additional purpose, what is it?
Which of the following causes the sharpest change in the equivalence point of a complexometric titration? A. Increasing the concentration of the EDTA solution B. Decreased concentration of the analyte C. Increasing the concentration of the EDTA solution D. Increasing the stability of the [metal-EDTA] complex
Chromel is an alloy composed of nickel, iron and chromium.A 0.6472 g sample was dissolved and diluted to 250 mL. When a50 mL aliquot of 0.05182 M EDTA was mixed with an equal volumeof the diluted sample and all the three ions were chelated, a 5.11 mLback titration with 0.06241 M copper (II) was required.The chromium in a second 50 mL aliquot was masked through theaddition of hexamethylenetetramine, titration of the Fe and Nirequired 36.28 mL of 0.05182 M EDTA.Iron and chromium were masked with pyrophosphate in a third50 mL aliquot and the nickel was titrated with 25.91 mL of theEDTA solution.Calculate the percentage of nickel, chromium and iron in thealloy.
You are given a table of [CN-] standard solutions of different concentration. A 25 mL aliquot of each standard solution was added with Fe(NO3)3 to form a colored complex[Fe(CN)6]3-(aq). Each standard solution was then diluted to a total volume of50.0 mL. [CN–] prior to dilution, M [CN-] final M 0 0 0.04 0.1 0.16 0.24 0.32 0.4 What are the new concentrations for the standard solutions? Please show solutions.
Volhard titration. A 30.00-mL solution of unknown I2 was treated with 50.00 mL of 0.365 0 M AgNO3. The precipitated AgI was filtered off, and the filtrate (plus Fe31) was titrated with 0.287 0 M KSCN. When 37.60 mL had been added, the solution turned red. How many milligrams of I2 were present in the original solution?
Use the data below to determine the % by mass of Fe to TWO decimal places, if a 0.02 M KMnO4 solution was used for the titration. gH * + MnO 4 + 5Fe 2+ -> SFe 3+ + Mn 2+ + 4H 20 (MM Fe = 56 a/moll mass of iron compound (g) 0.604 initial buret reading (mL) 0.94 Tinal buret reading (mL 16.21
Which of the following causes the sharpest change in the equivalence point of a complexometric titration? a) Increasing the concentration of the EDTA solution b) Decreased concentration of the analyte c) increase the stability of the [metal-EDTA] complex
A 50.00 ml aliquot of a solution containing Ca2+ and Mg2+ was buffered at pH 10 and titrated with 0.0474 M EDTA. The endpoint volume was 40.99 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 0.0474 M EDTA and the endpoint volume was found to be 30.04 ml.
Chromel is an alloy composed of nickel, iron and chromium. A 0.6553-g sample was dissolved and diluted to 250.0 mL. When a 50.00-mL aliquot of 0.05173 M EDTA was mixed with an equal volume of the diluted sample, all three ions were chelated, and a 5.34-mL back titration with 0.06139 M copper (II) was required.The chromium in a second 50.0-mL aliquot was masked through the addition of hexamethylenetetramine; titration of the Fe and Ni required 36.98 mL of 0.05173M EDTA. Iron and chromium were masked with pyrophosphate in a third 50.00-mL aliquot, and the nickel was titrated with 24.53 mL of the EDTA solution. Calculate the percentage of Cr in the alloy. Express your answer in 2 decimal places.
Chloride in a brine solution is determined using Volhard method. A 10.00 mL aliquot of the solution is treated with 25.00 mL standard 0.1182 M AgNO3 solution. The excess silver is titrated with standard 0.1010 M KSCN solution, requiring 12.38 mL to reach the red Fe(SCN)2+ end point. Identify the (a) indicator (b) end point color (c) molarity of the Cl- in sample.