A 0.700-g sample is analyzed spectrophotometrically for manganese by dissolving it in acid and transferring to a 250-ml flask and diluting to volume. Three aliquots are analyzed by transferring 50-mL portions with a pipet to 500-mL Erlenmeyer flasks and reacting with an oxidizing agent, potassium peroxydisulfate, to convert the manganese to permanganate. After reaction, these are quantitatively transferred to 250-mL volumetric flasks, diluted to volume, and measured spectrophotometrically. By comparison with standards, the average concentration in the final solution is determined to be 1.25 x 10-5 M. What is the percent manganese in the sample? 3.92% 0.12% 5.10% 0.03%

A 0.700-g sample is analyzed spectrophotometrically for manganese by dissolving it in acid and transferring to a 250-ml flask and diluting to volume. Three aliquots are analyzed by transferring 50-mL portions with a pipet to 500-mL Erlenmeyer flasks and reacting with an oxidizing agent, potassium peroxydisulfate, to convert the manganese to permanganate. After reaction, these are quantitatively transferred to 250-mL volumetric flasks, diluted to volume, and measured spectrophotometrically. By comparison with standards, the average concentration in the final solution is determined to be 1.25 x 10-5 M. What is the percent manganese in the sample? 3.92% 0.12% 5.10% 0.03%

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

Chapter17: Electrochemistry

Section: Chapter Questions

Problem 80AP

See similar textbooks

Similar questions

A 0.500g sample is analyzed spectrophotometrically for manganese by dissolving it in acid and transferring to a 250 mL flask and diluting to volume. Three aliquots ae analyzed by transferring 50 mL portions with a pipet to 500 mL Erlenmeyer flask and reacting with an oxidizing agent, potassium peroxydisulfate, to convert the manganese to permanganate. After reaction, these are quantitatively transferred to 250 mL volumetric flasks, diluted to volume and measured spectrophotometrically. By comparison with standards, the average concentration of the final solution is determined to be 1.25 x 10^-5M. What is the percent manganese in the sample?
A student determined fluoride in a toothpaste sample using ion chromatography. A toothpaste sample of mass 0.100 g was dissolved in type I water and then quantitatively filtered through a Whatman #1 filter paper into a clean 100 ml volumetric flask. The flask was then made up to volume with type I water and mixed thoroughly.A portion of the solution was filtered through a 0.45 um filter into a sample vial for analysis. Analysis of the sample gave a fluoride concentration of 1.60 mg/l Calculate the % w/w fluoride in the original toothpaste sample. (Give your answer to 3 decimal places please)
Five white, 500-mg uncoated ascorbic acid (AA) tablets with an average weight of 0.6100-g were pulverized in a mortar. A sample of the powdered ascorbic acid weighing 0.4610-g was placed in an iodine flask and was dissolved in 50-mL H2SO4 then 5-g of KBr was added to the resulting solution. The solution was titrated with 46.73-mL of 0.0152 M STD. KBrO3 to reach a faint yellow endpoint then 3-g KI and 5-mL Starch TS. The blue color solution is then titrated with 2.78-mL of 0.1047 M STD. Na2S2O3 to reach the disappearance of the blue iodostarch complex. MW: KBrO3 = 167.0 ; KIO3 = 214.0 ; Na2S2O3 = 158.11 ; C6H8O6 = 176.12 Compute the milligrams of pure AA per tablet from the assay. None of the choices 349.7 mg 264.3 mg 462.7 mg
A 2.0 g of MgCO3 was dissolved and diluted to exactly 500-mL volumetric flask. If 50-mL aliquot was used in the analysis, what is the weight of MgCO3 present in the aliquot sample
You are preparing a 100.0 mL standard solution needed for titration analysis. The NaOH (40 g/mol) pellets are measured to be 0.5341 g in a balance with acceptable uncertainty of +0.001 g. Mass of the pellets is recorded after taring the container. The pellets are put in a beaker and added with 50 ml distilled water measured by a graduated cylinder. The solution is then quantitatively transferred to a 100-mL volumetric flask with uncertainty of ±0.08 mL and diluted to a 100-mL mark. What is the concentration (M) of the solution and estimate its uncertainty by propagation? Assumption: There is no uncertainty in molar mass. Express your answer as C+/- u M.
In the Analytical Chemistry laboratory, one of the B.Sc student Ms. Fatma wanted to analyze the presence of Iron(II) ion in the water samples collected from Sohar Industrial Area in the Sultanate of Oman and analyzed by Spectrophotometric method. (1) 250.00 mL of this water sample (Solution A) known to contain unknown amount of FeSO4. She has diluted Solution A by a dilution factor 10 to make 250.00 mL solution, which she labeled Solution B. Using Spectrophotometer, she has measured the absorbance value (0.642) for Solution B at 508 nm using 1.00 cm cell (cuvet). The molar absorptivity value for Fe2* ion at 508 nm is ɛ508 = 30.8 M-1cm1. (i) What volume of the solution A did she require to make the 250.00 mL of Solution В? (ii) in (i)? What instrument should she use to transfer the volume of the Solution A calculated (ii) Concentration of FeSO4 in Solution B. (iv) Concentration of FeSO4 in Solution A. Mass of FeSO4 in Solution A (Show your calculation) (v)
ASSAY Calibration solutions Calibration solutions of naproxen in the range 5 – 25 μg/mL were prepared. Sample preparation 20 tablets weighing 12.3819 g were crushed to a fine powder. A portion of the powder (145.4 mg) was shaken with approximately 150 mL of acetic acid (0.05 M) for 5 min and then made up to volume in a 250 mL volumetric flask (stock solution). Approximately 50 mL of the stock solution was filtered and a 25 mL aliquot was diluted to 100 mL in a volumetric flask. 10 mL of the resulting solution was further diluted to 100 mL with acetic acid (0.05 M). Analysis The standards and sample solutions were analyzed by HPLC under the following conditions: Column: octadecylsilyl (ODS), 4.6 mmx150 mm, mobile phase: acetonitrile : 0.05 M acetic acid (85:15), flow rate: 1 ml/min, UV detection at 243 nm. Results: A calibration curve of concentration versus peak area was constructed for the standard solutions and gave the straight-line equation: y = 3555.6x + 85, r = 0.9999 The area…
In a similar experiment, the mass of 3 PB tablets was measujed to be 3.1177 g. The tablets were crushed, and 2.9862 g of the powder was transferred to a beaker and reacted with HCI. After filtration, the filtrate was transferred to a 50-mL volumetric flask and diluted with water. 10.00 mL of this stock solution was combined with 0.2 M NagPO4. The resulting precipitate weighed 0.2694 g after drying. What is the mass of BSS per tablet in mg? Round your answer to 1 decimal place.
A researcher reconstituted a vial of 750 mg Cefuroxime Sodium Powder for Injection with 6mL of sterile water for injection. The reconstituted solution was dark amber-colored solution. The package insert states that solution colors range from clear to yellow depending on concentration, diluent, and storage conditions. The researcher was then hesitant to give the patient the solution due to its unusual dark color. Five portions were taken from a batch of cefuroxime sodium. Prior to testing in the instrument, each part was subjected to one of the following conditions: Conditions Specifications Temperature Portion 1: 8°C ± 2°C Portion 2: 30°C ± 2°C Portion 3: 40°C ± 2°C Light Portion 4: Kept in the dark Portion 5: Exposed to direct sunlight 1. Of the several solutions prepared, which absorbance value results should be compared with each other to answer the questions of the pharmacist? Explain your answer.
A 20.0 mL sample of commercial bleach was diluted with water to a 250.0 mL volumetric flask. A 50.0 mL aliquot of the diluted sample was treated with excess KI and starch. The liberated iodine was titrated with 0.399 M Na2S2O3, requiring 13.9 mL to reach the end point. (a) Identify the type of redox titration method used. (b) Identify the indicator and endpoint color. (c) Calculate the % w/v NaOCl in the sample.
A student weighed approximately 1.5 g of an unknown solid acid and carefully placed the sample in a clean, but not necessarily dry, 250.0 mL volumetric flask. The student added deionized water to the flask, swirled the solution until the solid acid dissolved, then added sufficient deionized water to fill the flask to the fill line. A volumetric pipet was used to transfer 25.00 mL of the resulting solution to an Erlenmeyer flask, and 2 – 3 drops of phenolphthalein were added.The student filled the sodium hydroxide buret and titrated the acid solution with standardized 0.1000 M NaOH to the first permanent faint pink color, then repeated the titration a second time.Your instructor will provide the mass of unknown solid acid, as well as the initial and final buret readings for the two titrations. From this data and the information above, you will be able to calculate the molar mass of the unknown acid.The unknown solid acid is diprotic; that is, there are two moles of ionizable H+ ions per…
A student weighed approximately 1.5 g of an unknown solid acid and carefully placed the sample in a clean, but not necessarily dry, 250.0 mL volumetric flask. The student added deionized water to the flask, swirled the solution until the solid acid dissolved, then added sufficient deionized water to fill the flask to the fill line. A volumetric pipet was used to transfer 25.00 mL of the resulting solution to an Erlenmeyer flask, and 2 – 3 drops of phenolphthalein were added.The student filled the sodium hydroxide buret and titrated the acid solution with standardized 0.1000 M NaOH to the first permanent faint pink color, then repeated the titration a second time.Your instructor will provide the mass of unknown solid acid, as well as the initial and final buret readings for the two titrations. From this data and the information above, you will be able to calculate the molar mass of the unknown acid.The unknown solid acid is diprotic; that is, there are two moles of ionizable H+ ions per…