A 0.9092 g sample of wheat flour was analysed by the Kjeldahl procedure. The ammonia formed was distilled into 50.00 mL of 0.02532 M H2SO4. A 7.46 mL back titration of 0.04917 M NaOH was required. (Note the stoichiometry of your acid and base) Calculate the %N (FM=14.007) in the sample, %Protein in the sample (factor = 5.70)

A 0.9092 g sample of wheat flour was analysed by the Kjeldahl procedure. The ammonia formed was distilled into 50.00 mL of 0.02532 M H2SO4. A 7.46 mL back titration of 0.04917 M NaOH was required. (Note the stoichiometry of your acid and base) Calculate the %N (FM=14.007) in the sample, %Protein in the sample (factor = 5.70)

Chemistry & Chemical Reactivity

10th Edition

ISBN:9781337399074

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter4: Stoichiometry: Quantitative Information About Chemical Reactions

Section4.9: Spectrophotometry

Problem 3.1ACP

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A 0.9092 g sample of wheat flour was analyzed by the Kjeldahl procedure. The ammonia formed was distilled into 50.00 mL of 0.02532 M H2SO4. A 7.46 mL back-titration of 0.04917 M NaOH was required. (Note the stoichiometry of your acid and base) Calculate the a. %N (FM=14.007) in the sample, b. %Protein in the sample (factor = 5.70)
The Kjeldahl method was used to determine the nitrogen content of a protein. A 275 µL aliquot of a 47.0 mg/mL protein solution was digested in boiling sulfuric acid. The solution was made basic and the liberated NH, was collected in 5.00 mL of 0.0512 M HCl. A volume of 7.00 mL of 0.0174 M NaOH was required to react with the excess HCl. Calculate the weight percent of nitrogen in the protein. weight percent: wt% N
A 0.9092g sample of wheat flour was analyzed by Kjeldahl method. The ammonia formed was distilled into 50.00 mL of 0.05063 M HCl; a 7.46 mL back titration with 0.04917 M NaOH was required. Calculate the % protein in the flour. Input the value only. Express in 2 SF.
An unknown sample containing mixed alkali (NAOH, NaHCO3, or NazCO3) was analyzed using the double flask method. A 250 mg sample was dissolved in 250 mL CO, free water. A 20.0 mL aliquot of this sample required 11.3 mL of 0.009125 M HCI solution to reach the phenolphthalein end point. Another 29.0 mL aliquot of the sample was titrated to the bromocresol green endpoint using 311 mL of the standard acid. What is/are the component/s of the sample? O Cannot be determined O NAHCO3 only O NAOH and Na,CO3 O NazCO3 only O NAHCO, and Na2CO3
An unknown sample containing mixed alkali (NAOH, NaHCO3, or NazCO3) was analyzed using the double flask method. A 250 mg sample was dissolved in 250 mL CO, free water. A 20.0 mL aliquot of this sample required 11.3 mL of 0.009125 M HCI solution to reach the phenolphthalein end point. Another 29.0 mL aliquot of the sample was titrated to the bromocresol green endpoint using 31.1 mL of the standard acid. What is/are the component/s of the sample? O NazCO3 only NaHCO3 only O NAHCO3 and Na>CO3 NaOH and NazCO3 O Cannot be determined
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 end point. Report the purity of Na2CO3 sample.
A 1.43 x 10-4 L solution of 45.7 mg/mL protein was analyzed using the Kjeldahl procedure. After digestion of the protein, the liberated NH3 was collected in 9.80 mL of 0235 M HCl. The unreacted acid required 10.75 mL of a standard solution of 0.0149 M NaOH for complete titration. Calculate the weight percent of nitrogen in the protein. (Molar mass N = 14.00674 g/mol)
Example You determine the acetic acid content in vinegar by titrating with a standard (known concentration) solution of NaOH to a phenolphthalein endpoint. 5.023± 0.003 g sample of vinegar is weighed. The NaOH must be standardized by KHP and 3 such titrations gave molarities of 0.1167, 0.1163 and 0.1164 M. A volume of 36.78 ± 0.03mL NaOH is used to titrate the sample. What is the percent acetic acid in the vinegar and what is the overall uncertainty?Answer: 5.12% ± 0.01%
10-27. A 10.231-g sample of window cleaner containing ammonia was diluted with 39.466 g of water. Then 4.373 g of solution were titrated with 14.22 mL of 0.106 3 M HCl to reach a bromocresol green end point. (a) What fraction of the 10.231-g sample of window cleaner is contained in the 4.373 g that were analyzed? (b) How many grams of NH3 (FM 17.031) were in the 4.373-g sample? (c) Find the weight percent of NH3 in the cleaner.
A 0.5131-g sample that contains KBr (MM: 119.0023) is dissolved in 50 mL of distilled water. Titrating with 0.04614 M AgNO3 requires 25.13 mL to reach the Mohr end point. A blank titration requires 0.65 mL to reach the same end point. Report the %w/w KBr in the sample.
An unknown sample containing mixed alkali (NAOH, NaHCO3, or NazCO3) was analyzed using the double flask method. A 250 mg sample was dissolved in 250 mL CO2 free water. A 20.0 mL aliquot of this sample required 11.3 mL of 0.009125 M HCI solution to reach the phenolphthalein end point. Another 29.0 mL aliquot of the sample was titrated to the bromocresol green endpoint using 31.1 mL of the standard acid. How many millimoles of the components are there in the original solid sample? O 0.28 mmol Na,CO3 O 1.29 mmol NaOH, 0.97 mmol Na2CO3 O 0.103 mmol NaOH, 0.078 mmol NazCO3 O 1.29 mmol Na2CO3, 0.97 mmol NaHCO3 O Cannot be determined
A mixture containing only KCl and NaBr is analyzed by the Mohr Method. A 0.3172-g sample is dissolved in 50 mL water and titrated to the Ag2CrO4 endpoint, requiring 36.85 mL of 0.1120 M AgNO3. A blank titration requires 0.71 mL of titrant to reach the same endpoint. Report the % (w/w) KCl and NaBr in the sample. [Answer should be 82.41 % (w /w)]