A 0.4020 g sample was dissolved, and Ca2+ and Ba2+ ions present were precipitated as Ba.C2O4.H2O and CaC2O4H2O. The Oxalates were then heated in a thermogravimetric apparatus leaving a residue that weighed 0.3175 g in the range of 320°C to 440°C and 0.2165 g in the range of 580°C to 620°C. Calculate percentage Ca and percentage Ba in the sample.

A 0.4020 g sample was dissolved, and Ca2+ and Ba2+ ions present were precipitated as Ba.C2O4.H2O and CaC2O4H2O. The Oxalates were then heated in a thermogravimetric apparatus leaving a residue that weighed 0.3175 g in the range of 320°C to 440°C and 0.2165 g in the range of 580°C to 620°C. Calculate percentage Ca and percentage Ba in the sample.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter31: Introduction To Analytical Separations

Section: Chapter Questions

Problem 31.18QAP

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A 0.6025 g sample was dissolved and the Ca2+ and Ba2+ ions present were precipitated as BaC2O4.H2O and CaC2O4.H2O. The oxalates were then heated in a thermogravimetric apparatus leaving a residue that weighed 0.5713 g in the range 320oC to 400oC and 0.4674 g in the range 580oC to 620oC. Calculate the percentage Ba in the sample.
A 500.0mg of butter was warmed and shaken vigorously with water. The undissolved material was removed by filtering and the aqueous portion was made 1.0M in HNO3 and 0.025M in Fe(NO3)3. This acidified solution was treated with 10.00ml of 0.1755M AgNO3 to precipitate the chloride ion and, after the addition of a small amount of nitrobenzene, 14.22ml of 0.1006M KSCN was required to back titrated the excess Ag+. Calculate the % NaCl in the butter.
A 2.054 g of macrogol monostearate (average molecular weight 706. 5) was added to a 200 ml flask and 25 ml of an ethanolic solution of potassium hydroxide (molecular weight 56.1, ca 0.5 M) was added. The sample was heated under a reflux condenser for 1 hour. The excess of alkali was then titrated with 0.5016 M hydrochloric acid using phenolphthalein solution as an indicator. The operation was repeated without the macrogol monostearate. Results Volume of HCI required to titrate the excess alkali = 18.35 ml Volume of HCI required to titrate the blank = 24.03 ml Calculate the saponification value for the macrogol stearate. Answer: Blank mg/g
A chemist received different mixtures for analysis with the statement that they contained NaOH, NaHCO3, Na2CO3, or compatible mixtures of these substances, together with inert material. From the data given, identify the respective materials, and calculate the percentage of each component. 1.000g samples and 0.2500N HCl were used in all cases. (A) For Sample W: With PP, 24.32ml was used. A duplicate sample required 48.64ml with MO. (B). For Sample X: The addition of PP caused no color change. With MO, 38.47ml of the acid was required. (C). For Sample Y: To cause a color change in the cold with PP, 15.29ml of the acid was necessary, and an additional 33.19ml was required for complete neutralization. (D) For Sample Z: The sample was titrated with acid until the pink of PP disappeared; this process required 39.96ml. On adding an excess of the acid, boiling, and titrating back with alkali, it was found that the alkali was exactly equivalent to the excess acid added.
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A sample of anhydrous Na2CO3 (FM = 105.989) is suspected to be contaminated with eitherNaHCO3 (FM = 84.007) or NaOH (FM = 39.997) To verify the suspicion, a 0.7483 g sample was dissolved to prepare a 50.00 mL solution, and a 10.00 mL aliquot was taken to prepare a 100 mL solution, where 25.00 mL was analyzed using single flask method. If the sample requires 27.50 mL of standard 0.0125 N HCl to reach the phenolphthalein endpoint and another 28.40 mL to reach the bromcresol green endpoint, calculate the percentagecomposition (in %w/w) of all the basic components in the sample.
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