PROCEDURE Acidity 100 mL aliquots of the sample with a few drops of HCI, and boil gently for a few minutes to eliminate CO2. Cool, add 3 to 4 drops of methyl red, and neutralise with 0.1 M NaOH. Introduce 2 mL of pH-10 buffer, 3 to 4 drops of Eriochrome Black T, and titrate with the prepared standard NazHzY to a colour change from red to pure, blue (Note). Report the results in terms of milligrams of CaCO, per litre water. NOTE The colour change is sluggish if Mg? is absent. In this event, add 1 to 2mL of 0.1 Mg Y2- before starting the titration (see Section 36D-4 for the preparation of this solution). Data. Mass of NazH2Y.2H20 0,9989 g Titration Initial volume (ml) final volume (ml) Volume used (ml) ? 1 0,75 25.25 2 1.25 26,75 1,75 26,87 4 2,55 27.05 1.90 21.90

PROCEDURE Acidity 100 mL aliquots of the sample with a few drops of HCI, and boil gently for a few minutes to eliminate CO2. Cool, add 3 to 4 drops of methyl red, and neutralise with 0.1 M NaOH. Introduce 2 mL of pH-10 buffer, 3 to 4 drops of Eriochrome Black T, and titrate with the prepared standard NazHzY to a colour change from red to pure, blue (Note). Report the results in terms of milligrams of CaCO, per litre water. NOTE The colour change is sluggish if Mg? is absent. In this event, add 1 to 2mL of 0.1 Mg Y2- before starting the titration (see Section 36D-4 for the preparation of this solution). Data. Mass of NazH2Y.2H20 0,9989 g Titration Initial volume (ml) final volume (ml) Volume used (ml) ? 1 0,75 25.25 2 1.25 26,75 1,75 26,87 4 2,55 27.05 1.90 21.90

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter22: Bulk Electrolysis: Electrogravimetry And Coulometry

Section: Chapter Questions

Problem 22.33QAP

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[Standardization] 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 made and was determined to be 0.4 mL. [Analysis] A 30 mL unknown water sample was treated with 37.6 mL of EDTA. A blank correction was made and was determined to be 0.4 mL. What is the concentration of CaCO3 of the unknown water sample in ppm? (MW CaCO3 = 100.0869 g/mol)?
[Standardization] 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)? 5.050 x 10-3 M 0.1284 M 0.1262 M 5.135 x 10-3 M
Back titration. Impure K2S2O8 (FM 270.32, 0.507 3 g) was analyzed by treatment with excess standard Na2C2O4 in H2SO4. After reaction with 50.00 mL of 0.050 06 M Na2C2O4, the excess oxalate required 16.52 mL of 0.020 13 M KMnO4. Find the weight percent of K2S2O8 in the impure reagent.
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The buret was filled with 0.100 M HCl solution. Then was transferred in a 25.0 mL of saturated calcium hydroxide solution (2g of calcium hydroxide per 100 ml of water) in two separate E-flasks. Then 2 drops of phenolphthalein was added to each flask Titration data for the determination of solubility and Ksp of calcium hydroxide: Trial 2: Final Buret reading (ml)-26.10; Initial Buret reading (ml)- 19.80; Temperature (Celcius)- 25 Voume of HCl used: Trial 2- 6.30mL 1. Compute for the moles of H+ used and the moles of OH- present. moles of H+ used = (concentration of HCl) × (volume of HCl used)moles of OH- = moles of H+ used 2. Construct an ICE table for the reaction.3. Calculate the molar solubility (in mol/L) of OH- and Ca2+.4. Determine the solubility of Ca(OH)2 in g/L. (MM of Ca(OH)2 = 74.096 g/mol). 5. Calculate the Ksp of Ca(OH)26. Compute for the percent error of the experimental value for Ksp of Ca(OH)2 with the literature…
The buret was filled with 0.100 M HCl solution. Then was transferred in a 25.0 mL of saturated calcium hydroxide solution (2g of calcium hydroxide per 100 ml of water) in two separate E-flasks. Then 2 drops of phenolphthalein was added to each flask Titration data for the determination of solubility and Ksp of calcium hydroxide: Trial 1: Final Buret reading (ml)-19.80; Initial Buret reading (ml)- 13.00; Temperature (Celcius)- 25 Trial 2: Final Buret reading (ml)-26.10; Initial Buret reading (ml)- 19.80; Temperature (Celcius)- 25 Voume of HCl used: Trial 1- 6.80ml; Trial 2- 6.30mL 1. Compute for the moles of H+ used and the moles of OH- present. moles of H+ used = (concentration of HCl) × (volume of HCl used)moles of OH- = moles of H+ used 2. Construct an ICE table for the reaction.3. Calculate the molar solubility (in mol/L) of OH- and Ca2+.4. Determine the solubility of Ca(OH)2 in g/L. (MM of Ca(OH)2 = 74.096 g/mol). 5.…
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 made and was determined to be 0.4 mL. [Analysis] A 30 mL unknown water sample was treated with 37.6 mL of EDTA. A blank correction was made and was determined to be 0.4 mL. What is the concentration of Ca2+ (40.0780 g/mol) in ppm?
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)?
Determine the relationship between the observed/apparent value (EX) VERSUS that of the true value (ET) for the quantity being sought by writing either <, >, or = on the space provided Determination of water hardness using complexometric titration. During sample analysis (ppm CaCO3), the volume for blank correction was not subtracted to the volume of titrant. EX Blank 1 ET
20 aspirin tablets labeled 80mg were dissolved in 100mL of 90% ethanol. A 10mL aliquot was taken and was used for assay. The analyte followed usual process and was treated with 50mL of 0.1000N NaH and was titrated with 35mL 0.1050N H2O4 until the solution achieved completion. Calculate the % content of the total aspirin capsules and the actual label claim
Construct a titration curve (pCl^- vs. Vtitrant) for the titration of 25.0 mL of 0.100 M Cl^– solution with 0.100 M AgNO3. MS Excel® can be used. Titrant volumes: 0.00 mL, 10.00 mL, 15.00 mL, 20.00 mL, 25.00 mL, and 30.00 mL.AgCl: Ksp = 1.82 x 10^-10
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…