The Kjeldahl analysis is used to determine the protein content of foods. The food analyzed is heated with sulfuric acid in the presence of a catalyst. The carbon in the protein is converted to CO₂(g), the hydrogen to water, and the nitrogen to (NH4)2SO4. The mixture is then treated with concentrated NaOH(aq) and heated to drive off NH3(g). The NH3(g) is neutralized by an excess standard acid, and the acid present after the neutralization is titrated with a standard base. From the titration data and the known mass of the sample, the percentage of N can be calculated. Based on the fact that the average percentage of nitrogen in most plant and animal protein is 16.0%. the percentage of protein is obtained by multiplying the percentage of N by the factor (100/16) = 6.25. Analysis Now that the acid has been standardized and you know it is 0.2496 M H₂SO4. you perform the actual experiment as follows: A 2.900-g sample of meat is subjected to Kjeldahl analysis. The liberated NH3(g) is absorbed by adding 50.00 mL of H₂SO, (aq), which is more than enough. This occurs through the reaction 2NH₂(g) + H₂SO.(aq)-(NH₂), SO. (aq) The excess acid requires 19.90 mL of 0.5510 M NaOH for its complete neutralization Part B What is the percentage of protein in the meat? Express your answer numerically in percentage. View Available Hint(s) 196] ΑΣΦΑ Submit Previous Answers ? % protein

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Part b

The Kjeldahl analysis is used to determine the
protein content of foods. The food analyzed is
heated with sulfuric acid in the presence of a
catalyst. The carbon in the protein is converted to
CO₂(g), the hydrogen to water, and the nitrogen
to (NH4)2SO4. The mixture is then treated with
concentrated NaOH(aq) and heated to drive off
NH3(g). The NH3(g) is neutralized by an excess
standard acid, and the acid present after the
neutralization is titrated with a standard base. From
the titration data and the known mass of the
sample, the percentage of N can be calculated.
Based on the fact that the average percentage of
nitrogen in most plant and animal protein is 16.0%.
the percentage of protein is obtained by multiplying
the percentage of N by the factor (100/16)-6.25.
Analysis
Now that the acid has been standardized and you know it is 0.2496 M H₂SO4. you perform the actual experiment as
follows:
A 2.900-g sample of meat is subjected to Kjeldahl analysis. The liberated NH3(g) is absorbed by adding 50.00 mL of
H₂SO, (aq), which is more than enough. This occurs through the reaction
2NH₂(g) + H₂SO.(aq)-(NH₂), SO. (aq)
The excess acid requires 19.90 mL of 0.5510 M NaOH for its complete neutralization
Part B
What is the percentage of protein in the meat?
Express your answer numerically in percentage.
View Available Hint(s)
196] ΑΣΦΑ
Submit
Previous Answers
?
% protein
Transcribed Image Text:The Kjeldahl analysis is used to determine the protein content of foods. The food analyzed is heated with sulfuric acid in the presence of a catalyst. The carbon in the protein is converted to CO₂(g), the hydrogen to water, and the nitrogen to (NH4)2SO4. The mixture is then treated with concentrated NaOH(aq) and heated to drive off NH3(g). The NH3(g) is neutralized by an excess standard acid, and the acid present after the neutralization is titrated with a standard base. From the titration data and the known mass of the sample, the percentage of N can be calculated. Based on the fact that the average percentage of nitrogen in most plant and animal protein is 16.0%. the percentage of protein is obtained by multiplying the percentage of N by the factor (100/16)-6.25. Analysis Now that the acid has been standardized and you know it is 0.2496 M H₂SO4. you perform the actual experiment as follows: A 2.900-g sample of meat is subjected to Kjeldahl analysis. The liberated NH3(g) is absorbed by adding 50.00 mL of H₂SO, (aq), which is more than enough. This occurs through the reaction 2NH₂(g) + H₂SO.(aq)-(NH₂), SO. (aq) The excess acid requires 19.90 mL of 0.5510 M NaOH for its complete neutralization Part B What is the percentage of protein in the meat? Express your answer numerically in percentage. View Available Hint(s) 196] ΑΣΦΑ Submit Previous Answers ? % protein
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