Consider the following method for the analysis of cocaine (MW 303.35) powder. "Dissolve about 600 mg of cocaine, preciously dried and accurately weighed, in 50 mL of glacial acetic acid, add I drop of crystal violet TS, and titrate with 0.1 M perchloric acid VS to a green endpoint. Perform a blank determination, and make the necessary correction" Calculate the percentage purity of the cocaine sample from the data below. Show your reasoning clearly and record your final answer to four significant figures. • Cocaine powder weighed - 606.3 mg • Concentration of HCIO3 = 0.09978 M H₂C- Lo Volume HCIO; required for the assay mixture = 19.97 mL Volume HCIO; required for blank determination = 0.059 ml

Consider the following method for the analysis of cocaine (MW 303.35) powder. "Dissolve about 600 mg of cocaine, preciously dried and accurately weighed, in 50 mL of glacial acetic acid, add I drop of crystal violet TS, and titrate with 0.1 M perchloric acid VS to a green endpoint. Perform a blank determination, and make the necessary correction" Calculate the percentage purity of the cocaine sample from the data below. Show your reasoning clearly and record your final answer to four significant figures. • Cocaine powder weighed - 606.3 mg • Concentration of HCIO3 = 0.09978 M H₂C- Lo Volume HCIO; required for the assay mixture = 19.97 mL Volume HCIO; required for blank determination = 0.059 ml

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter31: Introduction To Analytical Separations

Section: Chapter Questions

Problem 31.19QAP

See similar textbooks

Similar questions

1. The surface of silica gel has a structure shown in the diagram below : OH OH OH -0- Si- 0 Si Si – 0- main body of silica structure Suppose you used a plate coated with silica gel, with propanone, CH;COCH;, as the solvent for thin layer chromatography. Suppose also that the mixture you were trying to identify contained A compound, P, which could form strong hydrogen bonds. A compound, Q, which formed hydrogen bonds, but not as strongly as P. A compound, R, which was polar, relying on dispersion forces and dipole-dipole interactions for its intermolecular attractions. Describe and explain what the chromatogram would probably look like.
A 0.1475-M solution of Ba(OH)2 was used to titrate the acetic acid (60.05 g/mol) in a dilute aqueous solution. The following results were obtained. (See attached image)(a) Calculate the mean w/v percentage of acetic acid in the sample.(b) Calculate the standard deviation for the results. (Take note if n-1 should be used)(c) Calculate the 90% confidence interval for the mean.(d) (d) At the 90% confidence level, could any of the results be discarded?
In a Complexometric Titration Experiment, the preparation of the EDTA solution is as follows: In a 250 mL beaker, weigh 0.10 g MgCl2*6H2O and 1.0 g NaOH. Add approximately 200 mL distilled water and stir to dissolve. Add about 2.0 g of EDTA and transfer the solution quantitatively to a 1-L volumetric flask. Dilute to the mark with distilled water. What is the purpose of adding MgCl2*6H2O? Please show COMPLETE solution.
250.0 ml of the mineral water sample was precipitated with potassium sodium tetraphenyl bromate: K+ + B(C6H5)4-  KB(C6H5)(s). The precipitate was filtered, washed and dissolved in an organic solvent. An excess of HgY2- was added to the solution: 4 HgY2- + B(C6H5)4- +4H2O  H3BO3 + 4C6H5Hg+ + 4HY3- + OH-. The liberated EDTA was titrated with 0.05581 M Mg 2+ solution, which consumed 29.64 mL. Calculate the potassium concentration [mg/l] in the sample.
2.) A 0.2185g sample of NaCl was assayed using Volhard Method with 50mL 0f 0.0998N AgNO3 and 11.9mL of 0.1350N NH4SCN. Calculate the % NaCl in the sample.
0.5 g mixture of (0.1 N KCI and 4 points KBr) is required to 58.03 mL of 0.1 N AGNO3 to precipitate both bromide and chloride as AgCl and AgBr. Calculate the weight percentage for each of the AgCl and AgBr in a mixture if you know that the molecular weight of KCI = 74.5 and of KBr = 119 * %3D
Complexometric titrations are generally conducted to determine divalent cations. The most important applications are the titration of calcium and magnesium with EDTA. (a) A supplement tablet containing about 300.00 mg of calcium ion was dissolved, filtered, and diluted to 100.00 ml volume. Several 2.00 ml samples of the total solution were titrated with 0.0100 M EDTA solution. The mean corrected titration volume was 13.65 mL. Calculate the calcium content of the supplement tablet in mg units. (b) A sample of Epsom Salt of mass 0.7567 g was dissolved uniformly in distilled water in a 250.00 mL volumetric flask. Portions of the magnesium ion solution of volume 10.00 mL were titrated using a 0.01000 M solution of EDTA. The mean corrected titration volume was 12.25 ml. Calculate the percentage by mass (% w / w) of the magnesium in the Epsom Salt sample. (c) A 100.00 mL sample of tap water was titrated with 0.0100 M EDTA solution. The mean corrected titration volume was 14.80 mL. Determine…
Describe a concise step by step lab procedure for preparing a standard aqueous solution containing 3.019 millimolar (mm) of Pb from solid lead nitrate Pb(NO3)2 analytical grade reagent with a high purity of 99.989 %. Show and state the relevant calculations and/or assumptions in each step of the procedure.
2. In one gravimetric analysis, the aluminum in a 1.2g sample of impure NHAI(SO4)2 was precipitate as hydrous ALO3.XH2O. The precipitate was filtered and ignited at 1000 °C to give anhydrous Al2O3 which weighed 0.1798g. Calculate the % Al inthe sample. 3. A sample of 0.4500g impure potassium chloride was dissolved in water treated with excess silver nitrate solution. 0.8402 g of silver chloride was precipitated. What is the percentage of potassium chloride in the sample?
A chemist received different mixtures for analysis with the statement that they contained NAOH, NaHCO3, Na,CO3 or compatible mixtures of these substances together with inert material. From the data given, identify the respective materials. Sample 4. The sample was titrated with acid until the pink of phenolphthalein disappeared; this process required 39.96 mL. On adding an excess of the acid, boiling and titrating back with NAOH, it was found that the base was equivalent to the excess acid. O A NazCO3, NaHCO3 OB. NaHCO3 O C. Na2CO3 O D. None of these O E. NaOH
A 0.1093-g sample of impure Na2CO3 was analyzed by the Volhard method. After adding 50.00 mL of 0.06911 M AgNO3, the sample was back-titrated with 0.05781 M KSCN, requiring 27.36 mL to reach the endpoint. Report the purity of the Na2CO3 sample. [Ans. 90.9 % (w /w )]
A piece of Gold weighing 12,359 Kg is suspected of being contaminated with Iron. To perform an instrumental analysis and To confirm whether or not it contains Fe, a portion of the sample (0.954 g) is taken from the piece and dissolved with 25 mL of aqua regia. Heats up For its complete dissolution, it is cooled and made up to 100 mL. A 10 mL aliquot is taken from this solution and made up to 50 mL. From This last solution is given the appropriate treatment to visualize Fe+2, for which the 1,10-phenanthroline reagent is added. (it forms a complex that is red in color) and is taken to a visible spectrophotometer and with a 12 mm cell a absorbance of 0.45. Previously, a calibration curve of Fe+2 was obtained under the same instrumental conditions obtaining the following data: (view table) Calculate the purity of the gold piece, assuming impurities only due to Fe.