A sample of alfalfa meal weighing 2.0 g is analyzed by Kjeldahl method for the percentage of nitrogen. The liberated NH3 is caught in a solution of H3BO3, and 8.23 ml of HCl are required in the subsequent titration. A sample of pure (NH4)2SO4 (132.12) weighing 0.61 g is treated with excess NaOH and the liberated NH3 (17.04) is also caught in H3BO3. The resulting solution requires 20 ml of the acid for titration. Calculate the percentage of protein in the sample using 6.25 as the factor.

A sample of alfalfa meal weighing 2.0 g is analyzed by Kjeldahl method for the percentage of nitrogen. The liberated NH3 is caught in a solution of H3BO3, and 8.23 ml of HCl are required in the subsequent titration. A sample of pure (NH4)2SO4 (132.12) weighing 0.61 g is treated with excess NaOH and the liberated NH3 (17.04) is also caught in H3BO3. The resulting solution requires 20 ml of the acid for titration. Calculate the percentage of protein in the sample using 6.25 as the factor.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter16: Applications Of Neutralization Titrations

Section: Chapter Questions

Problem 16.40QAP

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The protein content of wheat flour can be determined reasonably accurately by multiplying the percentage of nitrogen present by 5.7. A 2.06-g sample of flour was taken through a Kjeldahl procedure and the ammonia produced was distilled into a boric acid solution. If this solution required 34.70 mL of 0.174 N HCl for titration to the methyl red end point, what is the a) % Nitrogen and b) % protein in the flour? (Use 1:1 stoich ratio between N and HCl)
The amount of protein in a sample of cheese is determined by a Kjeldahl analysis for nitrogen. After digesting a 0.9814-g sample of cheese, the nitrogen is oxidized to NH4+, converted to NH3 with NaOH, and distilled into a collection flask containing 50.00 mL of 0.1047 M HCl. The excess HCl is then back titrated with 0.1183 M NaOH, requiring 22.84 mL to reach the bromothymol blue end point. Report the %w/w protein in the cheese given that there is 6.38 g of protein for every gram of nitrogen in most dairy products.
For breakfast, the nihilistic Rick Sanchez ate 100 g of cereal mixed with 20 g of milk. A 1.500 g sample of the same cereal was analyzed using the Kjeldahl method, and the liberated NH3 was distilled into 50 mL of a 0.0227 M HCl solution, and back-titrated with 2.85 mL of 0.0112 M NaOH solution. A 1.100 g sample of milk was also analyzed, and the liberated NH3 was distilled into 55 mL of a 0.0234 M HCl solution, and back-titrated with a 3.10 mL of 0.0121 M NaOH. Use the values: MM N=14.07 g/mol. meat= 6.25 dairy= 6.38 cereal= 5.70 What is the % protein in the cereal sample? What is the % protein in the milk sample?
For breakfast, the nihilistic Rick Sanchez ate 100 g of cereal mixed with 20 g of milk. A 1.500 g sample of the same cereal was analyzed using the Kjeldahl method, and the liberated NH3 was distilled into 50 mL of a 0.0227 M HCl solution, and back-titrated with 2.85 mL of 0.0112 M NaOH solution. A 1.100 g sample of milk was also analyzed, and the liberated NH3 was distilled into 55 mL of a 0.0234 M HCl solution, and back-titrated with a 3.10 mL of 0.0121 M NaOH. Use the values: MM N=14.07 g/mol. meat= 6.25 dairy= 6.38 cereal= 5.70 1. What is the % protein in the cereal sample? a. 5.90% protein b. 10.21% protein c. 11.80% protein d. 20.42% protein 2. What is the % protein in the milk sample? a. 5.90% protein b. 10.21% protein c. 11.80% protein d. 20.42% protein 3. How many grams of protein did Rick consume over-all? a. 3.749 g b. 7.942 g c. 5.901 g d. 10.21 g
A 1.250 g sample of cheese was subjected to a Kjeldahl analysis to determine the amount of protein. The sample was digested, the nitrogen is oxidized to NH₄⁺, and was then converted to NH₃ with NaOH, and distilled into a collection flask containing 50.00 mL of 0.1050 M HCl. The excess HCl is back titrated with 0.1175 M NaOH, this required 21.65 mL to reach the bromothymol blue end point. A. How many moles of N is present in the cheese sample? B. Report the %N of the cheese sample. C. Report the %protein of the cheese sample, assuming that there are 6.4 grams of protein for every gram of nitrogen
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