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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: DUDE778 on February 25, 2008, 12:36:26 PM

Title: Kjeldahl Nitrogen Analysis
Post by: DUDE778 on February 25, 2008, 12:36:26 PM

A 0.282-g sample of feed is analyzed for nitrogen using the Kjeldahl method.
The ammonia generated is absorbed into 80.00 mL of 0.04000-M HCl.
The excess HCl is then titrated with 41.61 mL of 0.01081-M NaOH.
Given that the nitrogen content of the protein in the feed is 15.97% by mass, determine the percentage protein in the sample.

How would i do it?  Ive never heard of this.
 ???

Title: Re: Kjeldahl Nitrogen Analysis
Post by: Arkcon on February 25, 2008, 12:58:30 PM

First, you'll write balanced equations for the two titration reactions, with the intention of finding out how much ammonia was generated.  You'll later use the 15.97% conversion factor to determine protein.  The Kjeldahl method is a MacGuffin, you don't have to know how it works to (at least start) solving the problem.