9) Cr³+ reacts slowly with EDTA (Y4-) so it is usually analyzed using back-titration. A 100.0 mL treated water sample containing only Cr³+ was diluted to 1 L and 25.0 mL 0.005 M Y4- was added to a 10 mL aliquot of the diluted sample. The excess Y4- required 23.0 mL 0.005 M CaCl2 to reach the EBT end-point. Find the ppm Cr³+ in the water sample. a.) 5.2 ppm b.) 52 ppm c.) 520 ppm d.) 5200 ppm

9) Cr³+ reacts slowly with EDTA (Y4-) so it is usually analyzed using back-titration. A 100.0 mL treated water sample containing only Cr³+ was diluted to 1 L and 25.0 mL 0.005 M Y4- was added to a 10 mL aliquot of the diluted sample. The excess Y4- required 23.0 mL 0.005 M CaCl2 to reach the EBT end-point. Find the ppm Cr³+ in the water sample. a.) 5.2 ppm b.) 52 ppm c.) 520 ppm d.) 5200 ppm

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter12: Spectrochemical Methods

Section: Chapter Questions

Problem 15P

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A 15.00 mL urine specimen containing Ca2+ and Mg2+ was diluted to 2.000 L. A 10.00 mL sample was taken and buffered to a pH of 10 and required 27.32 mL of 0.003960 M EDTA to react with 'all' the Ca²+ and Mg2+. A second 10.00 mL sample was taken and all the Ca²+ was precipitated as Ca(C204)(s). The Ca(C2O4) (s) precipitate was then taken and dissolved in 18.00 mL of water, buffered to a pH of 10, and required 12.21 mL of 0.003960 M EDTA solution to react with all the Ca2+. Calculate the concentration of Ca²+ and Mg2+ in the original urine specimen.
A solid containing tris was dissolved in water and brought to a total volume of 50.00 ml. A 10.00 ml aliquot of the solution was titrated with 0.09978 M HCl to a bromcresol green endpoint. The aliquot consumed 38.93 ml of titrant. Calculate the weight of tris in the original sample.
5. A 300.0 mg sample containing Na,CO3, NaHCO3 and NaOH and inert material either alone or in some combination was dissolved and titrated with 0.1000 M HCI the titration required 24.41 mL to reach the phenolphthalein endpoint. And an additional 8.67 mL to reach the methyl red endpoint. Determine the composition of the sample and calculate the percent of each titrated component.
A 25.00 ml of Ni2+ solution was diluted in HCl and treated with 25.00 ml of 0.05283 MNa2EDTA. The solution was neutralized with NaOH followed by addition of acetate buffer untilthe pH 5.5. The solution turns yellow after addition of few drops of xylenol orange indicator.Back titration using standard 0.022 MZn2+ at pH 5.5 requires 17.61 ml until end point, onwhich the solution will turn red. Calculate for the molarity of the unknown.
2. Titration of Ca²+ and Mg²+ in a 50mL sample of hard water required 23.65mL of 0.01205M EDTA. A second 50mL aliquot was made strongly basic with NaOH to precipitate Mg2+ as Mg(OH)2. The supernatant liquid was titrated with 14.53mL of the EDTA solution. Calculate a. concentration in ppm of CaCO3 in the sample. b. concentration in ppm of MgCO3 in the sample.
5. A 300.0 mg sample containing Na,CO3, NaHCO, and NaOH and inert material either alone or in some combination was dissolved and titrated with 0.1000 M HCI the titration required 24.41 ml to reach the phenolphthalein endpoint. And an additional 8.67 mL to reach the methyl red endpoint. Determine the composition of the sample and calculate the percent of each titrated component.
A 567.9 mg sample containing Na2CO3, NaHCO3 , NaOH and inert material was dissolved and titrated with 0.1002 M HCl. The titration required 24.30 mL to reach the phenolphthalein endpoint and an additional 38.67 mL to reach the methyl red endpoint. Determine the composition of the sample and the % of each titrated component.
The Merck Index indicates that 10 mg of guanidine,CH5N3, may be administered for each kilogram of bodymass in the treatment of myasthenia gravis. The nitrogenin a 4-tablet sample that had a total mass of 7.50 g wasconverted to ammonia by a Kjeldahl digestion, followedby distillation into 100.0 mL of 0.1750 M HCl. Theanalysis was completed by titrating the excess acid with11.37 mL of 0.1080 M NaOH. How many of thesetablets represent a proper dose for a patient who weighs(a) 100 lb, (b) 150 lb, and (c) 275 lb?
A 25.00 ml of Ni2* solution was diluted in HCI and treated with 25.00 ml of 0.05283 M NazEDTA. The solution was neutralized with NaOH followed by addition of acetate buffer until the pH 5.5. The solution turns yellow after addition of few drops of xylenol orange indicator. Back titration using standard 0.022 MZn2* at pH 5.5 requires 17.61 ml until end point, on which the solution will turn red. Calculate for the molarity of the unknown. Ans. 0.03664 M
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A 20 ml aliquot of malonic acid solution was treated with 10.0 ml of 0.25M Ce4+ leading to the reaction CH2(COOH)2 + 6Ce4+ + 2H2O ® HCOOH + 2CO2 + 6Ce3+ + 6H+ After standing for 10 minutes at 60oC, the solution was cooled and the x’ss Ce4+ was titrated with 0.1M Fe2+, requiring 14.4 ml to reach the ferroin end point. Calculate the M of the malonic in the sample.
A 50.00 ml aliquot of a solution containing Ca2+ and Mg2+ was buffered at pH 10 and titrated with 0.0418 M EDTA. The endpoint volume was 44.36 ml. A second aliquot of the same mixture was made strongly basic by the addition of NaOH – this causes the Mg2+ to precipitate as Mg(OH)2. The solution was then titrated with the 0.0418 M EDTA and the endpoint volume was found to be 30.02 ml. Calculate the molar concentration of Mg.