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
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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