4. The %Mn in steel can also be determined spectrophotometrically by oxidizing the manganese to the intensely colored permanganate, MnO4. Standard solutions of permanganate gave the following absorbances (in a 1 cm cell): ABSORBANCE CONC. OF MnO4 (g/mL) 1.05 x 10-5 0.210 0.315 0.429 0.599 0.801 1.61 x 10-5 0.5886 0.3498 0.4555 2.21 x 10-5 2.98 x 10-5 4.04 x 10-5 The following samples of steel were thoroughly reacted to convert the manganese into permanganate and then diluted to 500.00 mL. WT. OF STEEL (g) gud atstattet. (00mL ho val pipil ABSORBANCE 0.611 0.359 0.482 Again, using Excel, plot the calibration data and calculate the %Mn in the steel. Print and attach the calibration curve and present your calculations. hodinkon

4. The %Mn in steel can also be determined spectrophotometrically by oxidizing the manganese to the intensely colored permanganate, MnO4. Standard solutions of permanganate gave the following absorbances (in a 1 cm cell): ABSORBANCE CONC. OF MnO4 (g/mL) 1.05 x 10-5 0.210 0.315 0.429 0.599 0.801 1.61 x 10-5 0.5886 0.3498 0.4555 2.21 x 10-5 2.98 x 10-5 4.04 x 10-5 The following samples of steel were thoroughly reacted to convert the manganese into permanganate and then diluted to 500.00 mL. WT. OF STEEL (g) gud atstattet. (00mL ho val pipil ABSORBANCE 0.611 0.359 0.482 Again, using Excel, plot the calibration data and calculate the %Mn in the steel. Print and attach the calibration curve and present your calculations. hodinkon

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter19: Complex Ions

Section: Chapter Questions

Problem 46QAP

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4. The %Mn in steel can also be determined spectrophotometrically by oxidizing the manganese to the intensely colored permanganate, MnO4-. Standard solutions of permanganate gave the following absorbances (in a 1 cm cell): ABSORBANCE CONC. OF MnO4 (g/mL) 0.210 1.05 x 10-5 0.315 1.61 x 10-5 0.429 2.21 x 10-5 0.599 2.98 x 10-5 0.801 4.04 x 10-5 The following samples of steel were thoroughly reacted to convert the manganese into permanganate and then diluted to 500.00 mL. WT. OF STEEL (g) ABSORBANCE 0.5886 0.611 0.3498 0.359 0.4555 0.482 Again using Excel, plot the calibration data and calculate the %Mn in the steel.
A sample of steel was dissolved and the manganese present was converted to MnO4– (aq). Water was then added to give a final solution volume of 100.00 mL. A sample of this solution was examined and was found to have an absorbance at 525 nm of 0.600 (pathlength = exactly 1 cm). What is the concentration of MnO4– in the solution? (The molar absorptivity is 3.62 × 103 L/(mol cm).)
Gold can be determined in solutions containing high concentrations of diverse ions by ICP. Aliquots of 50.0 mL of the sample solution were transferred to each of four 100.0 mL volumetric flasks. A solution was prepared containing 10.0 mg/L Au in 20% H2SO4, and quantities of this solutions were added to the sample solution to give 0, 2.5, 5 and 10 mg/L added Au in each of the flask. The solutions were made up to a total volume of 100.0 mL, mixed and analyzed by ICP. The resulting data are presented in the following table: Added Au (mg/L) Emission Intensity (Counts) 0.0 12568 2.5 19324 5.0 26622 10.0 40021 a) Attach an excel graph for the determination showing the X intercept. b) Calculate the concentration of gold in the sample, report with its uncertainty. c) The known concentration of gold in the sample is 8.51 mg/L. Test the hypothesis that your result is equal to this value at the 95% confidence level. l
The iron content of a large lump of ore is determined by taking a single small sample, dissolving it in acid, and titrating with ceric sulphate after reduction of Fe (III) to Fe (II). What are the possible source of random and systematic errors?
The absorbances of solutions containing K2CrO4 in 0.05 M KOH were measured in a 1.0-cm cell of 375 nm. The following results were obtained: Calculate the concentration of K2CrO4 (g/L) if the A is 0.550.
What are the maximum atomic and weight percentages of Cu that can be added to Au without exceeding a resistivity that is thrice that of pure gold? (Alloys are normally prepared by mixing the elements in weight. Resistivity of Au at 0°C is 20.5 nΩ m Nordheim coefficient for Cu in Au at 20°C is C = 450 nΩ m. Resistivity of Au at 20°C, using α0 = 1/242 K-1 )
A spectrophotometric method for the analysis of iron has a linear calibration curve for standards of 0.00, 5.00, 10.00, 15.00, and 20.00 ppm. An iron ore sample with an expected iron content of 40–60% w/w is to be analyzed by this method. An approximately 0.5-g sample is taken, dissolved in a minimum of concentrated HCl, and diluted to 1 L in a volumetric flask using distilled water. A 5.00-mL aliquot is removed with a pipet. To what volume (10, 25, 50, 100, 250, 500, or 1000 mL) should it be diluted to minimize the uncertainty in the analysis? Explain.
Which of the following salts does NOT cause permanent hardness? A FeCl, B CaCl, © Ca(HCO,), (НСО ,), D MgSO 4
A standard iron solution was prepared by dissolving 0.0140 g of pure iron in acid then transferring to a 50.00 mL volumetric flask with orthophenanthroline as a complexing agent. At a wavelength of 540 nm, the absorbance of the standard was 0.214 in a 1.00 cm cuvette. A 0.128 g sample of an iron ore was crushed and digested in 5 mL of concentrated acid. The digested sample was then transferred to a 10.00 mL volumetric flask and diluted to the mark with water. A 1.00 mL aliquot of the sample was transferred to a 25.00 mL volumetric flask, and diluted to the mark with water. A portion of the diluted sample was then transferred to a 1.00 cm cuvette and measured at a wavelength of 540 nm. The resulting absorbance was 0.216. Determine the % w/w of Fe in the iron ore.
Determination of metals in soil by AAS Soil Mass of Soil ppm (mg/L) Concentration of Cu in soil Absorbance 1 1.0101g 0.6545 2 1.0064g 0.6203 3 1.0018g 0.5287 Show the calculation on how to calculate the ppm and the concentration of copper in the sample (soil). (The final volume is 200mL)
2 MnO4- (aq) + 5 C2O42- (aq) + 16 H+ (aq) « 2Mn2+ (aq) + 10 CO2 (g) + 8 H2O(l) 0.4040 g of the unknown compound (K2Zy(C2O4)z . nH2O) was dissolved in 100.0 mL water to make a solution. It was then heated to 80oC and titrated with a KMnO4 solution as shown below: The molarity of KMnO4 = 0.0.02321 M Volume used = 29.25 mL A.) What is the % Oxalate by mass for the unknown solid titrated?
show solutions 1. 10.000 grams of Clay was analyze for Iron content. Its moisture content is 2.00%. The sample was digested with oxidizing acids to convert all Iron into Fe3+. An excess of NH4OH was added and yielded a gelatinous precipitate of Fe(OH)3. The sample was then ignited in a furnace and yielded 0.1212 grams of residue as Fe2O3. Calculate the percentage of Iron. 2. A 0.3000 gram sample contains only KCl and CaCl2. The sample was dissolved in water and yielded 0.5000 grams of AgCl upon addition of excess AgNO3 reagent. Calculate the percentage of KCl and MgCl2.