A 0.425 g sample of steel is dissolved in acid, and the manganese oxidized to permanganate. The solution is made up to 100 mL in a volumetric flask and the absorbance at 520 nm in a 2.0 cm cell is 0.80. The molar absorptivity of permanganate at 520 nm is 2235. Calculate the percentage of Mn in the steel.

A 0.425 g sample of steel is dissolved in acid, and the manganese oxidized to permanganate. The solution is made up to 100 mL in a volumetric flask and the absorbance at 520 nm in a 2.0 cm cell is 0.80. The molar absorptivity of permanganate at 520 nm is 2235. Calculate the percentage of Mn in the steel.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter26: Molecular Absorption Spectrometry

Section: Chapter Questions

Problem 26.15QAP

See similar textbooks

Similar questions

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.
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 is linkage isomerisation and why can it be important?
Manganese silicide has the empirical formula MnSi andmelts at 1280 °C. It is insoluble in water but does dissolvein aqueous HF. (a) What type of compound do you expectMnSi to be: metallic, molecular, covalent-network, orionic? (b) Write a likely balanced chemical equation for thereaction of MnSi with concentrated aqueous HF.
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.
To measure the nickel content in steel, the alloy is dissolved in 12 M HCl and neutralized in the presence of citrate ion, which maintains iron in solution. The slightly basic solution is warmed, and dimethylglyoxime (DMG) is added to precipitate the red DMG-nickel complex quantitatively. The product is filtered, washed with cold water, and dried at 110°C. a) If 1.1634 g of steel gives 0.1795 g of precipitate, what percentage of Ni is in the steel?
1. A 0.9882 gram sample of iron ore is dissolved, the iron reduced to Fe2+, and the solution was titrated with 36.40 mL of 0.02065 M KMnO4 in acid solution. (a) Write the titration reaction. (b) Calculate the %FeO (M.M. = 71.85) in the sample. 2. A sample of primary standard grade K2Cr2O7 (MM = 294.20) weighing 0.2153 g is dissolved, the solution acidified and excess KI added. The liberated I2 requires 44.86 mL of the Na2S2O3 for titration. (a) Write the titration reaction. (b) Calculate the molarity of the titrant solution. Box the final answer.
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) What is the percentage of MnO2 in a pyrolusite ore if a sample weighing 0.4000 g is treated with a 0.6000 g of pure H2C2O4.2H20 and dilute H2SO4 and after reduction has taken place (MnO2 + H2C2O4 + 2H+ Mn2+ + 2CO2 + 2H2O), the excess oxalic acid requires 26.26 mL of 0.1000 N KMNO4 for titration? (b) If pure As2O3 were used instead of oxalic acid, how many grams would be required in order for the other numerical data to remain the same?
A 0.4852g sample of an iron ore was dissolved in acid to the 3+ state, then precipitated as Fe2O3 x H2O. The pp was filtered, washed and calcined to Fe2O3, which gave a weight of 0.2481g. Calculate the Fe % in the sample.
1) Balance the following in acidic solution: (a) Н2О + Sn2+ Н,0 + Sn++ (b) PBO2 + Hg –→ H* + P²+ (c) Al + Cry0; – A+ + Cr+
An alloy containing Ni, Fe and Cr was analyzed by a complexation titration using EDTA as titrant. A 0.7176 g sample of the alloy was dissolved in HNO3 and diluted to 250 mL in a flask. A 50.00 mL aliquot of the sample, treated with pyrophosphate to mask Fe and Cr, required 26.14 mL of 0.05831 M EDTA to reach the murexide endpoint. A second 50.00 mL aliquot was treated with hexamethylenetetramine to mask Cr and titration with 0.05831 M EDTA required 35.43 mL to reach the murexide endpoint. Finally, a third 50.00 mL aliquot was treated with 50.00 mL of 0.05831 M EDTA and titrated back to the murexide endpoint with 6.21 mL of 0.06316 M Cu(II). the weight percentages of Ni, Fe and Cr in the alloy.