A 0.850 g sample of wheat flour was subjected to a Kjeldahl analysis. The ammonia formed after digestion was distilled into 30.00 mL of 0.0650 M HCl. The excess HCl was back titrated with 6.50 mL of 0.0400 M NaOH. Calculate the %N and %protein (factor = 5.70) in the flour.

A 0.850 g sample of wheat flour was subjected to a Kjeldahl analysis. The ammonia formed after digestion was distilled into 30.00 mL of 0.0650 M HCl. The excess HCl was back titrated with 6.50 mL of 0.0400 M NaOH. Calculate the %N and %protein (factor = 5.70) in the flour.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter17: Complexation And Precipitation Reactions And Titrations

Section: Chapter Questions

Problem 17.35QAP

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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
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. What is the reaction for the digestion of the limestone sample A. 2 NaOH + CaCO₃ ⇌ Na₂CO₃ + Ca(OH)₂ B. 2 HCl + CaCO₃ ⇌ CaCl₂ + H₂O + CO₂ C. CaCO₃ ⇌ CaO + CO₂ D. NaOH + HCl ⇌ NaCl + H₂O
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. What is the reaction for the back titration for this analysis? a. NH₄⁺ + NaOH ⇌ NH₃ + H₂O + Na⁺ b. NaOH + HCl ⇌ NaCl + H₂O c. NH₃ + HCl ⇌ NH₄⁺ + Cl⁻ d. N₂ + 3 H₂ ⇌ 2 NH₃ How many moles of N is present in the cheese sample? a. 544 x 10⁻³ b. 706 x 10⁻³ c. 250 x 10⁻³ d. 794 x 10⁻³ Report the %N of the cheese sample. a. 851% b. 884% c. 033% d. 736%
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