AIIMS 2006 Chemistry Acidity of Amines Assertion Reason Question

To address the given question, let's analyze both the assertion and the reason carefully.

Assertion:

Anilinium chloride is more acidic than ammonium chloride.

Analysis: Anilinium chloride ($C_6H_5NH_3Cl$) is the salt formed from aniline and hydrochloric acid. On the other hand, ammonium chloride ($NH_4Cl$) is formed from ammonia and hydrochloric acid.

The acidity of a compound can be evaluated based on the stability of its conjugate acid. When anilinium chloride donates a proton (H$^+$), it forms the anilinium ion ($C_6H_5NH_3^+$). This ion is stabilized by resonance, as the positive charge can be delocalized over the aromatic ring. The resonance structures can be depicted as follows:

$$\text{Resonance structure 1:} \quad C_6H_5N^+H_2$$

$$\text{Resonance structure 2:} \quad C_6H_4^+=N^+H_2$$

This delocalization of charge increases the stability of the anilinium ion compared to the ammonium ion ($NH_4^+$), which does not have any resonance stabilization.

Conclusion on Assertion:

Since the anilinium ion is more stable due to resonance, anilinium chloride is indeed more acidic than ammonium chloride. Thus, the assertion is true.

Reason:

Anilinium ion is resonance-stabilised.

Analysis: The reason provided is accurate. The anilinium ion benefits from resonance stabilization because the positive charge can be shared across multiple resonance structures. This makes the anilinium ion more stable compared to the ammonium ion, which lacks such resonance stabilization.

Conclusion on Reason:

The reason is true and correctly explains why anilinium chloride is more acidic than ammonium chloride.

Final Evaluation:

Both the assertion and the reason are true and the reason is the correct explanation of the assertion. Therefore, the correct option should be: A) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

However, the correct answer provided in the question is C) Assertion is true but Reason is false. This indicates a misunderstanding in the question itself because the reason is actually true.

Incorrect Options:

• Option B: Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. This option cannot be correct since the reason is indeed a correct explanation.
• Option D: Both Assertion and Reason are false. This is incorrect because both are true.

Summary:

The correct answer should logically be A based on the provided information. However, if the question states C as the correct answer, it implies an error in the question or answer choices.

In conclusion, anilinium chloride is more acidic than ammonium chloride due to the resonance stabilization of the anilinium ion, making both the assertion and reason true.