Question

For which of the following compounds Kjeldahl method can be used to determine the percentage of Nitrogen ?

• A. Nitrobenzene
• B. Pyridine
• C. Alanine
• D. Diazomethane

Answer 1

The Correct Option is C

The Kjeldahl method is a classic method used to determine the nitrogen content in organic compounds. It is particularly suitable for compounds in which nitrogen is present in the form of amino or amide groups. Let's analyze each of the given options to see which is suitable for the Kjeldahl method.

1. Nitrobenzene: In nitrobenzene, nitrogen is present in the form of a nitro group (\text{-NO}_2). The Kjeldahl method is not suitable for nitro compounds as the nitrogen in the nitro group is not converted into ammonia through the usual digestion process.
2. Pyridine: Pyridine is a heterocyclic aromatic compound with nitrogen as a part of the ring. The nitrogen in pyridine is not easily converted into ammonium sulfate in the Kjeldahl process, making the method unsuitable for compounds like pyridine.
3. Alanine: Alanine is an amino acid with an amine group (\text{-NH}_2). The Kjeldahl method works well with amino acids as the nitrogen in the amino group can be converted into ammonia, which is then measured. Therefore, alanine is an appropriate compound for nitrogen determination using this method.
4. Diazomethane: Diazomethane contains nitrogen in a diazo group (\text{-N}_2), making it unsuitable for the Kjeldahl method as the nitrogen from such groups is not easily converted into ammonium form.

Thus, among the given options, Alanine is the compound suitable for determining the percentage of nitrogen using the Kjeldahl method.