How to Find out the Percentage of Nitrogen in an Organic Compound – Part 2

The Kjeldahl method (or digestion) is a quantitative analytical method for a sample's organic nitrogen plus ammonia/ammonium (NH3/NH4+).


Other forms of inorganic nitrogen, for instance, nitrate, are not included in this measurement without modification. It has been an important method for indirectly quantifying protein content of a sample using an empirical relation between Kjeldahl nitrogen and protein; however, adulteration by substances, viz., Melamine fails this method for the quantification of proteins. An advanced method, say, mass spectrometry may be used for a precise and accurate measurement of a protein.

Question:

A sample of 0.50 g of an organic compound was treated according to Kjeldahl method. The ammonia evolved was absorbed in 50 mL of 0.50 M H2SO4. The residual acid required 60 mL of 0.50 M solution of NaOH for neutralization. Find the percentage composition of nitrogen in the compound.

Solution: 



Click/tap to enlarge the image

Keen on Kjeldahl method❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com❗

References:

(1)    Ncert. Chemistry : Textbook for Class XI - Part.II; National Council Of Educational Research And Training: New Delhi.

(2)    Wikipedia Contributors. Kjeldahl method. Wikipedia. https://en.wikipedia.org/wiki/Kjeldahl_method.

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