A sample of steel weighing 2.00 g is analyzed for Cr (AW 52.0). The Cr is oxidized into chromate with alkaline permanganate and the excess permanganate is destroyed. A certain volume of 0.120 M FeSO, is added to the acid solution and the excess is titrated with 0.0220 M KMNO4, requiring 31.0 mL. If the sample contained 0.50 % Cr, what volume (in mL) of FeSO, was added?

A sample of steel weighing 2.00 g is analyzed for Cr (AW 52.0). The Cr is oxidized into chromate with alkaline permanganate and the excess permanganate is destroyed. A certain volume of 0.120 M FeSO, is added to the acid solution and the excess is titrated with 0.0220 M KMNO4, requiring 31.0 mL. If the sample contained 0.50 % Cr, what volume (in mL) of FeSO, was added?

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter13: Titrations In Analytical Chemistry

Section: Chapter Questions

Problem 13.27QAP

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A sample of steel weighing 2.00 g is analyzed for Cr (AW 52.0). The Cr is oxidized into chromate with alkaline permanganate and the excess permanganate is destroyed. A certain volume of 0.120 M FeSO4 is added to the acid solution and the excess is titrated with 0.0220 M KMnO4, requiring 31.0 mL. If the sample contained 0.50 % Cr, what volume (in mL) of FeSO4 was added?
(a) What is the percentage of MnO2 in a pyrolusite ore if a sample weighing 0.4000g is treated with 0.6000g of pure H2C2O4•2H2O and dilute H2SO4 and after reduction has taken place (MnO2 + H2C2O4 + 2H+→ Mn2++ 2CO2 + 2H2O), the excess oxalic acid requires 26.26ml of 0.1000N 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?
The Sn in a 0.4352 g mineral specimen was reduced to the +2 state and titrated with 29.77 mL of 0.01735 M K2Cr2O7. Identify: (a) method of redox titrimetry used (Dichrometry, Cerimetry, iodimetry, iodometry or, permanganometry) (b) appropriate indicator and its type (c) color at the end point (d) weight percent Sn (118.71 g/mol) in the sample
what wt. of limestone containing 9.57% Mg must be taken for analysis in order to precipitate of 0.551g Mg2P2O7? how many grams of Na2SO4 are required to ppte Ag2SO4 from 2.000t of AgNO3? a sample of magnetite (impure Fe3O4) weighing 0.5000g is fused with oxidizing flux and the ferric compound formed is eventually precipitated as ferric hydroxide and ignited to ferric oxide which weighs 0.4980calculate %Fe & %Fe2O3
To analyze the amount of iron (Fe; Mw = 55.85 g/mol) contained in an ore sample, the sample was digested with acid and diluted to 50 mL with water. This solution was then treated with 25.00 mL of 0.2922 M EDTA. The excess EDTA was back titrated with 6.47 mL of 0.0843 M Zn2+ to reach the equivalence point. How many grams of Fe contained in the ore sample?
Determine the percentage of iron in a sample of limonite from the following data:weight of sample = 0.5000g volume of KMNO4 added 50.0mL ; 1.00mL Kmno4 = 0.0005507 g fevolume of FeSO4 used for back titration 8.00mL ; 1.00mL FeSO4= 0.008950 g FeOMW: Fe= 55.85 FeO= 71.84
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 0.9352g sample of ore containing Fe³+, Al³+ and Sr²+ was dissolved and made up to 500.00 mL. The analysis of metals was performed using complexation volumetry. Initially, an aliquot of 50.00 mL had its pH adjusted to 1.0 and titrated with a standard 0.03145 mol/L EDTA solution, requiring 6.95 mL to reach the end point. Subsequently, another 25.00 mL aliquot was buffered at pH=5 and titrated with the same EDTA solution, requiring 6.24 mL to reach the end point. Finally, a third aliquot of 25.00 mL was titrated at pH=11, requiring 11.10 mL of the same EDTA solution to complete the titration. Given the molar masses: Fe=55.845 g/mol; Al-26.982 g/mol and Sr-87.620 g/mol. a) Determine the percentage of each of the metals in the sample. b) Explain why the change in pH allows the determination of the three ions in this sample.
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.
A sample of feldspar weighing 1.500g is decomposed, and eventually there is obtained a mixture of KCl and NaCl weighing 0.1801 g. These chlorides are dissolved in H2O, a 50-mL pipetful of 0.08333 N AGNO3 is added, and the precipitate is filtered off. The filtrate requires 16.47 mL of 0.1000N KCNS, with ferric alum as indicator. Calculate the percentage of K2O in the silicate.
When I was a boy, I watched Uncle Wilbur measure the iron content of runoff from his banana ranch. He acidified a 25.0-mL sample with HNO3 and treated it with excess KSCN to form a red complex. (KSCN itself is colorless.) He then diluted the solution to 100.0 mL and put it in a variablepathlength cell. For comparison, he treated a 10.0-mL reference sample of 6.80 3 1024 M Fe31 with HNO3 and KSCN and diluted it to 50.0 mL. The reference was placed in a cell with a 1.00-cm pathlength. Runoff had the same absorbance as the reference when the pathlength of the runoff cell was 2.48 cm. What was the concentration of iron in Uncle Wilbur’s runoff ?
For Redox Analysis of Iron... ~0.02 M of potassium dichromate is prepared as titrant for dried unknown. ~.3 g of sample, 50ml of 6M HCl, 20mL SnCl2, 10 mL of saturated HgCl2 solution, 60 mL of 3M H2SO4, 15mL of concentrated H3PO4, 100mL DI water. HCl (+ heat in fumehood until samples dissolves), SnCl2 (added with pipet until solution changes from yellow to colorless/light green with 3 drops in excess), HgCl2 (after cooling), H2SO4, H3PO4, DI Water, is added to the sample solution with 8 drops of diphenylamine sulfonate indicator then titrated with the potassium dichromate to a violet blue endpoint. 4. Why is it necessary to carry out the reduction of iron and then the titration, before going on to the next sample 5. If you look carefully, there are pieces of tin metal on the bottom of the SnCl2 reagent solution. Why is it there?