The standardization of same titrant during the determination of BOD5 of water sample was done separately for Day 1 and Day 5. Upon standardization, it turned out that the concentration of the titrant in Day 1 is higher than the concentration of the same batch of titrant in Day 5. How would you explain this discrepancy? A There were bubbles at the tip of the burette during titration. (B) Too much starch indicator was added in the conical flask. Sulfuric acid was added first before potassium iodide. D) The water used to prepare the Na₂S₂O3 solution was not boiled resulting to proliferation of bacteria.

The standardization of same titrant during the determination of BOD5 of water sample was done separately for Day 1 and Day 5. Upon standardization, it turned out that the concentration of the titrant in Day 1 is higher than the concentration of the same batch of titrant in Day 5. How would you explain this discrepancy? A There were bubbles at the tip of the burette during titration. (B) Too much starch indicator was added in the conical flask. Sulfuric acid was added first before potassium iodide. D) The water used to prepare the Na₂S₂O3 solution was not boiled resulting to proliferation of bacteria.

Principles of Modern Chemistry

8th Edition

ISBN:9781305079113

Author:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Publisher:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Chapter20: Molecular Spectroscopy And Photochemistry

Section: Chapter Questions

Problem 67CP

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The standardization of same titrant during the determination of BOD5 of water sample was done separately for Day 1 and Day 5. Upon standardization, it turned out that the concentration of the titrant in Day 1 is higher than the concentration of the same batch of titrant in Day 5. How would you explain this discrepancy? The water used to prepare the Na2S2O3 solution was not boiled resulting to proliferation of bacteria. Too much starch indicator was added in the conical flask. Sulfuric acid was added first before potassium iodide. There were bubbles at the tip of the burette during titration.
Why is the use of high-precision volumetric material essential for titration?
What is a 3 point calibration in titration?
All of the following criteria must be met for a titrimetric analysis to be feasible EXCEPT: Select one: a. Reaction between the standard and analyte must be known. b. There should be a substance for endpoint detection c. Reaction must proceed quantitatively to completion. d. Reaction between the reactants must be slow.
Why did the colour of the solution in the conical flask change at the end of the titration?
Is the standardization of titrant always the first step in all titrimetric analysis? Why or why not?
At any stage of the saponification experiment of ethyl acetate, when the 25mL sample taken from the mixture is taken into a flask containing 0.05M 15mL HCl and titrated with 0.05M NaOH, if the consumption is 10mL, calculate the remaining NaOH concentration without reacting over the reactions.
You have performed an iodimetric titration using a commercial vitamin C tablet. Based on the following information below, calculate the %(w/w) of vitamin C(MM=176.16 g/mol) in the tablet: Mass of tablet dissolved in 250.0 mL: 5.422 g Aliquot volume of sample titrated: 25.00 mL Concentration of KIO3: 0.023 M Final burrette volume: 41.31 mL Initial burrette volume: 8.89 mL Blank volume: 0.14 mL
An indicator was not used during potentiometric titration of a weak acid Is there a positive error, negative error, no effect, or error could not be determined In terms of the Computed pKa of the unknown weak acid?
In how much volume of diluted sulfuric acid should you dissolve a multivitamin tablet of approximately 1700 mg of Vitamin C to back analyze 10.00 mL of that solution, with 25.00 mL of 0.01 M KIO3 and 0.04 M thiosulfate to use approximately 8-10 mL of titrant ? You have 25, 50, 150, 250 and 500 mL flasks.
Three-point calibration was not performed on the pH meter prior to titration. Is there a positive error, negative error, no effect, or error could not be determined In terms of the Computed pKa of the unknown weak acid?
In order for all of the analyte to be consumed completely, an excess of a reagent has to be added. If 10.00 mL of a 0.1000 M HCl is needed in the back titration, what volume of a 0.5000 M NaOH should be added to a sample that contains 2.000 mmol of aspirin