After removing the membranes from an eggshell, the shell is dried and its mass recorded as 5.613 g. The eggshell is transferred to a 250-mL beaker and dissolved in 25 mL of 6M HCl. After filtering, the solution containing the dissolved eggshell is diluted to 250 mL in a volumetric flask. A 10.00-mL aliquot is placed in a 125-mL Erlenmeyer flask and buffered to a pH of 10. Titrating with 0.04988 M EDTA requires 44.11 mL to reach the end point. Determine the amount of calcium in the eggshells as % w/w CaCO3.

After removing the membranes from an eggshell, the shell is dried and its mass recorded as 5.613 g. The eggshell is transferred to a 250-mL beaker and dissolved in 25 mL of 6M HCl. After filtering, the solution containing the dissolved eggshell is diluted to 250 mL in a volumetric flask. A 10.00-mL aliquot is placed in a 125-mL Erlenmeyer flask and buffered to a pH of 10. Titrating with 0.04988 M EDTA requires 44.11 mL to reach the end point. Determine the amount of calcium in the eggshells as % w/w CaCO3.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter16: Applications Of Neutralization Titrations

Section: Chapter Questions

Problem 16.20QAP

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After removing the membranes from an eggshell, the shell is dried and its mass recorded as 5.613 g. The eggshell is transferred to a 250-mL beaker and dissolved in 25 mL of 6 M HCl. After filtering, the solution containing the dissolved eggshell is diluted to 250 mL in a volumetric flask. A 10.00-mL aliquot is placed in a 125-mL Erlenmeyer flask and buffered to a pH of 10. Titrating with 0.04988 M EDTA requires 44.11 mL to reach the end point. Determine the amount of calcium in the eggshell as %w/w CaCO3.
A 0.4071-g sample of pure CaCO3 was transferred to a 500-mL volumetric flask, dissolved using a minimum of 6 M HCl, and diluted to volume. After transferring a 50.00-mL portion of this solution to a 250-mL Erlenmeyer flask, the pH was adjusted by adding 5 mL of a pH 10 buffer. After adding an indicator, the solution was titrated with the EDTA, requiring 42.63 mL to reach the end point. What is the concentration of EDTA? Choices: 0.0191 M, 0.0955 M, 0.00955 M, 0.477 M
Chitinase is a protein that breaks down chitin, a primary component of the cell wall in fungi, scales in fish and exoskeletons of arthropods. The activity of chitinase extracted from a plant was shown to be optimum at pH 5. You were tasked to prepare 300 mL of 150 mM buffer solution for further analysis of the extracted chitinase. REAGENTS Ka 2.5M Acetic acid Solid NaOAc•3H2O [136.08g/mol] 1.76 x 10-5 2.5M NH3 Solid NH4Cl [53.49g/mol] 5.6 x 10-10 2.5M Lactic acid Solid sodium lactate [112.06g/mol] 4.0 x 10-5 5 M HCl 5M NaOH What are the moles of the (1) acid and (2) base components, given the following reagents? What is the mass/volume of the components needed to prepare the buffer solution?
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
What is the difference between alkalinity and buffering capacity?
please explain the process and answer Mouthwash acts to clean and disinfect mouths. Two important considerations when designing a mouthwash solution are the pH, which should ideally not be too acidic (where saliva has a normal pH range of 6.2–7.6 and below pH 5.5 erosion may occur), and the resistance of the solution to changes in pH. One example of a buffering system used in mouthwash is based on the compound H3PO4 which has PKa values of 2.1, 7.2 and 12.3. i. Hand-draw the structure of the main phosphorus species at pH 7.0, as well as a balanced equilibrium equation showing the structures of the two main phosphoric acid species at pH 7.0.
The protein content of wheat flour can be determined reasonably accurately by multiplying the percentage of nitrogen present by 5.7. A 2.06-g sample of flour was taken through a Kjeldahl procedure and the ammonia produced was distilled into a boric acid solution. If this solution required 34.70 mL of 0.174 N HCl for titration to the methyl red end point, what is the a) % Nitrogen and b) % protein in the flour? (Use 1:1 stoich ratio between N and HCl)
In a titration, 10.543 mL of a 1.112 M weak acid solution are placed in a 125 mL Erlenmeyer flask. A 1.249 M solution of NaOH (aq) is placed in the buret and filled to the 0.00 mL mark. NaOH solution is added to the flask and the buret reading is now 18.119. What is the pH of the solution? Enter your answer with at least 4 sig figs. The pKa of the weak acid is 4.954. (please type answer not write by hend)
A piece of Gold weighing 12,359 Kg is suspected of being contaminated with Iron. To perform an instrumental analysis and To confirm whether or not it contains Fe, a portion of the sample (0.954 g) is taken from the piece and dissolved with 25 mL of aqua regia. Heats up For its complete dissolution, it is cooled and made up to 100 mL. A 10 mL aliquot is taken from this solution and made up to 50 mL. From This last solution is given the appropriate treatment to visualize Fe+2, for which the 1,10-phenanthroline reagent is added. (it forms a complex that is red in color) and is taken to a visible spectrophotometer and with a 12 mm cell a absorbance of 0.45. Previously, a calibration curve of Fe+2 was obtained under the same instrumental conditions obtaining the following data: (view table) Calculate the purity of the gold piece, assuming impurities only due to Fe.
To determine the concentration of glucose in the packaged juice industry, 50 mL of sample is analyzed. Analysis of it (and other reducing sugars) was carried out there using triiodide back titration. An excess volume of 75.00 mL of 0.338 M triiodide standard solution in alkaline medium was added to the glucose solution. The resulting solution was acidified and the excess triiodide was titrated with 18.37 mL of standard 0.526 M thiosulfate solution. Calculate is the concentration in ppm in the sample. In alkaline medium: Glucose (C6H12O6) / Gluconate (C6H11O7-), Triiodide (I3- ) / Iodide (I-) In acid medium: Thiosulfate (S2O32-) / Tetrathionate (S4O62-), Triiodide (I3- ) / Iodide (I-)
You have a solution that contains acetic acid, (CH3COOH or HAc). The concentration of acetic acid in the aqueous solution is 0.35 mol / dm3. Ka = 1.7378 x 10 ^ -5 M a. Calculate the pH of the solution. 15 cm 3 of the acetic acid solution was titrated with sodium hydroxide solution, NaOH (aq), at a concentration of 0.5 mol / dm3 b. Describe how you would proceed to perform a titration of an acid of unknown concentration. What information can be obtained from a titration, describe the different phases. c. How much NaOH will be added when the equivalence point occurs?
A mixture containing only KCl and NaBr is analyzed by the Mohr Method. A 0.3172-g sample is dissolved in 50 mL water and titrated to the Ag2CrO4 endpoint, requiring 36.85 mL of 0.1120 M AgNO3. A blank titration requires 0.71 mL of titrant to reach the same endpoint. Report the % (w/w) KCl and NaBr in the sample. [Answer should be 82.41 % (w /w)]