COMPLEX PREPARED (preparation #3 ) cuciz H20 Starting metal salt (MX H,0) copper (IT)chloride dinydrate Metal (Cu or Co) cu Halide (Cl or Br) CL Amine (en, bu, pz, or dien) bu (1] Vield of the Complex Mass of crystalline product (Exp. Yield) 29.682 (2a) Determination of Copper Calculate the mols of NaS;O, to reach the end point, and then calculate the moles of Cu from the stoichiometry. Finally, calculate the % Cu in the sample. Show your calculations on the next page. Trial 2 Trial 1 O.103g 20.5mL 0.19 Mass of product,g Vol. of Na;S;O, to reach the end point, ml. Molarity of NazS;0, (from bottle) O.0100M Mols of Na;S:O, 0.0002.05 0.000210 0.00020S O:000 210 Mols of Cu Mass of Cu, g 0.0130 0.0 133 % Cu in product Ave % Cu Calculations: 0.100M = mol 0.0 20SL 63.55 = 1 0.0002 DS %3D

COMPLEX PREPARED (preparation #3 ) cuciz H20 Starting metal salt (MX H,0) copper (IT)chloride dinydrate Metal (Cu or Co) cu Halide (Cl or Br) CL Amine (en, bu, pz, or dien) bu (1] Vield of the Complex Mass of crystalline product (Exp. Yield) 29.682 (2a) Determination of Copper Calculate the mols of NaS;O, to reach the end point, and then calculate the moles of Cu from the stoichiometry. Finally, calculate the % Cu in the sample. Show your calculations on the next page. Trial 2 Trial 1 O.103g 20.5mL 0.19 Mass of product,g Vol. of Na;S;O, to reach the end point, ml. Molarity of NazS;0, (from bottle) O.0100M Mols of Na;S:O, 0.0002.05 0.000210 0.00020S O:000 210 Mols of Cu Mass of Cu, g 0.0130 0.0 133 % Cu in product Ave % Cu Calculations: 0.100M = mol 0.0 20SL 63.55 = 1 0.0002 DS %3D

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter26: Molecular Absorption Spectrometry

Section: Chapter Questions

Problem 26.15QAP

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The red color of soil is often due to the presence of iron. Metal ions are extracted from soil by stirring the soil in acid and then filtering the solution. One method for the analysis of Fe2+ is to form the highly colored Fe2+–thioglycolic acid complex. The complex absorbs strongly at 535 nm. Calibration standards of 1.00, 2.00, 3.00, 4.00, and 5.00 ppm are prepared by transferring appropriate amounts of a 10.0 ppm working solution of Fe2+ into separate 50-mL volumetric flasks, each of which contains 5 mL of thioglycolic acid, 2 mL of 20% w/v ammonium citrate, and 5 mL of 0.22 M NH3. After diluting to volume and mixing, the absorbances of the standards are measured. a)What is the effect on the reported concentration of iron in the sample if there is a trace impurity of Fe2+in the ammonium citrate?
The red color of soil is often due to the presence of iron. Metal ions are extracted from soil by stirring the soil in acid and then filtering the solution. One method for the analysis of Fe2+ is to form the highly colored Fe2+–thioglycolic acid complex. The complex absorbs strongly at 535 nm. Calibration standards of 1.00, 2.00, 3.00, 4.00, and 5.00 ppm are prepared by transferring appropriate amounts of a 10.0 ppm working solution of Fe2+ into separate 50-mL volumetric flasks, each of which contains 5 mL of thioglycolic acid, 2 mL of 20% w/v ammonium citrate, and 5 mL of 0.22 M NH3. After diluting to volume and mixing, the absorbances of the standards are measured. a)Use the data table below to prepare a calibration curve (absorbance versus concentration in ppm). Fit the data to straight line and find the equation for the straight line and the R2 value. (Hint: Think about what to do with the absorbance of the blank.)
(a) A compound with formula RuCl3 . 5 H2O is dissolved inwater, forming a solution that is approximately the samecolor as the solid. Immediately after forming the solution,the addition of excess AgNO3(aq) forms 2 mol of solid AgClper mole of complex. Write the formula for the compound,showing which ligands are likely to be present in the coordinationsphere. (b) After a solution of RuCl3 . 5 H2O hasstood for about a year, addition of AgNO3(aq) precipitates 3mol of AgCl per mole of complex. What has happened inthe ensuing time?
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 ?
You have been sent to India to investigate the occurence of goiter disease attributed to iodine deficency. As part of of your investigation, you must make field measurements of traces of Iodide(I-) in groundwater. The procedure is to oxidize I- to I2 and convert the I2 into an intensely colored complex with the dye brilliant green in the organic solvent toluene. a) A 3.15x10^-6 M solution of the colored complex exhibited an absorbance of 0.267 at 635nm in a 1.00cm cuvet. A blank solution made from distilled water in place of groundwater had an absorbance of 0.019. Find the molar absroptivity of the colored complex. b)The absorbance of an unknown solution prepared from ground water was 0.175. Find the concentration of the unknown.
Scott test is one of the methods used for screening for Cocaine in Forensic Chemistry. The multi step method consists of a) reacting the sample drug with cobaltous thiocyanate b) dissolving of the formed precipitate by adding HCl and c) extraction of coordination compound with Chloroform d) measurement of absorbance of extracted coordination compound at 627 nm All the reactions in this multistep method are not fully understood. However, it was determined that there are 2 moles of cocaine in coordination compound measured in last step. If coordination compound is represented as “Scott” coordination compound, which of the following is correct “stoichiometric” factor to get mass of cocaine from mass of measured complex ? a.g (Scott coordination cpd) * MM (Scott coordination cpd) MM (cocaine) b.g (Scott coordination cpd) * 2 *MM (Scott coordination cpd) MM…
A protein binds a ligand with a KD value of 0.25 M. If you are at a ligand concentration of 0.63 M, what is the fraction bound? Please report your answer to two significant figures. There should be no units in your answer
A solution of sodium thiosulfate, Na2S2O3 was standardized by dissolving 0.188 g of KIO3 (MM = 214.00) in water, adding a large excess of KI, and acidifying with HCl. The liberated iodine required 18.25 mL of the thiosulfate solution to decolorize the blue starch/iodine complex. Calculate the molarity of Na2S2O3 solution. Stoichiometry of the reaction is: 1 mol IO3- = 3 mol I2 = 6 mol S2O32-
A 25.00 mL aliquot of a solution containing Cu2+ and Fe3+ was titrated with 17.08 mL of 0.05095 M EDTA. A second 25.00 mL aliquot of the Cu/Fe mixture was treated with NaF to form a stable iron-fluoride complex. This mixture was then titrated with EDTA and the endpoint volume was found to be 5.47 mL. Calculate the amounts of Cu2+ and Fe3+ in mg/L. Molar mass (g/mol): Fe = 55.85 and Cu = 63.55
A sample contains Pb2+, Mg2+ and Zn2+. 0.4085 g of the sample is weighed and dissolved. Once dissolved it is with cyanide to form a complex and mask the zinc (Zn2++ 4 CN-→ Zn (CN)4 2-). The Pb2+ and Mg2+ in the solution are titrated with 42.22 mL of EDTA 0.02604 M. Then the Pb complex is treated with another organic ligand that masks Pb and releases EDTA, which is titrated with 19.35 mL of a Mg2+ 0.007657 M solution. For finalize formaldehyde is added to unmask the Zn2+(Zn (CN)4 2- + 4 HCHO + 4 H2O → Zn2+ + 4 HOCH2CN + 4 OH-). The liberated zinc is titrated with EDTA 0.02064 M consuming 28.63 mL. (Data: Pat Pb, 207.22; Pat Mg, 24.31; Pat Zn, 65.4). Find the percentage of the three metals in the sample.
complex formation equilibria with Ag+ for EDTA, CN-, NH3, I-
Sketch structure of Mo(DMe) Cl2 (NMe,)2 , thhen apply ean to this complex showing ligand analysis and oxidation state analysis