"Published in Newark, California, USA"
A 5.8734 gram sample of beef was analyzed for N content and the liberated ammonia was collected in a 50.00 mL of 0.4691 M HCl and a 12.55 mL back titration with 0.0256 M NaOH was required. Calculate the percentage protein in the beef sample.
Solution:
The given word problem is about volumetric analysis in which the titration of a sample and a solution is involved. By Kjeldahl method, we can analyze the amount of protein present in any organic samples.
If liberated ammonia is titrated with HCl solution, then the chemical reaction is
and the solution is back titrated with NaOH solution is
The amount of liberated ammonia in a sample is
By gravimetric analysis, the amount of nitrogen present in a sample is
Therefore, the percent of nitrogen or protein in a sample of beef is
