Question

Given below are two statements :
Statement (I) : Kjeldahl method is applicable to estimate nitrogen in pyridine.
Statement (II) : The nitrogen present in pyridine can easily be converted into ammonium sulphate in Kjeldahl method.
In the light of the above statements, choose the correct answer from the options given below.

• A. Both Statement I and Statement II is false
• B. Statement I is false but Statement II is true
• C. Both Statement I and Statement II is true
• D. Statement I is true but Statement II is false

Answer 1

The Correct Option is A

The question asks whether the Kjeldahl method is applicable for estimating nitrogen in pyridine and whether the nitrogen in pyridine can be easily converted to ammonium sulphate via this method.

1. Kjeldahl Method: This method is commonly used for determining the nitrogen content in chemical substances, primarily those organic compounds containing nitrogen in the form of ammonia or amines. The process involves digestion, neutralization, and titration to convert nitrogen into ammonium sulfate which is then measured.
2. Pyridine: Pyridine is a heterocyclic aromatic organic compound with the chemical formula \(C_5H_5N\). It has nitrogen in the form of a pyridine ring, which is not amenable to ready conversion into ammonia under the usual conditions of the Kjeldahl method.
3. Statement Evaluation:
   • Statement I: "Kjeldahl method is applicable to estimate nitrogen in pyridine."

This is false. The nitrogen in pyridine is part of a stable aromatic ring, which does not get converted into ammonia easily in the Kjeldahl digestion process. Hence, the Kjeldahl method is not appropriate for determining nitrogen in pyridine.

• Statement II: "The nitrogen present in pyridine can easily be converted into ammonium sulphate in Kjeldahl method."

This is also false. As mentioned earlier, the nitrogen in pyridine is not readily convertible to ammonium sulphate because of its stable aromatic nature.

Conclusion: Both Statement I and Statement II are false. The correct answer is: Both Statement I and Statement II is false.

Answer 2

The given question involves understanding the suitability of the Kjeldahl method for estimating nitrogen content in different compounds, particularly pyridine.

• Statement (I): Kjeldahl method is applicable to estimate nitrogen in pyridine.
• Statement (II): The nitrogen present in pyridine can easily be converted into ammonium sulphate in Kjeldahl method.

To determine the correctness of these statements, let's delve into the principles of the Kjeldahl method:

The Kjeldahl method is a widely used procedure for estimating the nitrogen content in organic compounds. It is particularly effective for compounds containing nitrogen in the form of amines, amides, imides, and heterocyclic compounds with readily convertible nitrogen atoms. However, it may not be suitable for certain nitrogen-containing compounds.

Analysis of the Statements:

1. Analysis of Statement (I): The Kjeldahl method does not typically apply to aromatic heterocyclic compounds such as pyridine. Pyridine contains nitrogen in a heterocyclic ring, where the nitrogen is tightly bound and not easily converted into ammonium ion. Therefore, estimating nitrogen in pyridine using this method is not feasible.
2. Analysis of Statement (II): The nitrogen in pyridine is not easily convertible into ammonium sulphate in the Kjeldahl method due to its stable aromatic structure and the nature of the nitrogen atom's participation in aromaticity. Therefore, this statement is also false.

Conclusion:

Both statements are false because the Kjeldahl method is not suitable for estimating nitrogen in pyridine due to the reasons outlined above.

Thus, the correct answer is: Both Statement I and Statement II is false.