Problem 17 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The conjugate base of hydrazoic acid is: (a) \(\mathrm{N}^{-3}\) (b) \(\mathrm{N}_{3}^{-}\) (c) \(\mathrm{N}_{2}^{-}\) (d) \(\mathrm{HN}_{3}^{-}\)

Step-by-Step Solution

Answer

(b) \(\mathrm{N}_{3}^{-}\)

Step 1: Understand the Concept of Conjugate Bases

A conjugate base is formed when an acid donates a proton (\(\mathrm{H}^{+}\)). In this case, we are looking for the conjugate base of hydrazoic acid, which is \(\mathrm{HN}_{3}\).

Step 2: Write the Acid-Base Reaction

The acid-base reaction for hydrazoic acid can be expressed as: \(\mathrm{HN}_{3} \rightarrow \mathrm{N}_{3}^{-} + \mathrm{H}^{+}\). Here, hydrazoic acid \(\mathrm{HN}_{3}\) donates a proton to form its conjugate base \(\mathrm{N}_{3}^{-}\).

Step 3: Identify the Correct Option

Compare the conjugate base \(\mathrm{N}_{3}^{-}\) with the given options:(a) \(\mathrm{N}^{-3}\)(b) \(\mathrm{N}_{3}^{-}\)(c) \(\mathrm{N}_{2}^{-}\)(d) \(\mathrm{HN}_{3}^{-}\)The correct match is option (b) \(\mathrm{N}_{3}^{-}\).

Key Concepts

Hydrazoic Acid

Hydrazoic acid, chemically represented as \(\mathrm{HN}_{3}\), is a simple and intriguing inorganic acid. It's a weak acid known for its explosive nature, especially in pure form. Hydrazoic acid consists of one hydrogen atom linked to a linear chain of three nitrogen atoms. This molecular structure makes it unique.

• Originates from azide ions \(\mathrm{N}_{3}^{-}\), which help stabilize it.
• Its linear nitrogen chains create the potential for releasing energy violently.

To understand its behavior in acid-base reactions, recognizing its structural composition and inherent instability is crucial. Hydrazoic acid often appears in discussions about chemical safety due to the explosiveness of its salts, and it serves a niche role in specialized organic transformations.

Acid-Base Reaction

Acid-base reactions are fundamental to chemistry. They involve the transfer of protons from acids to bases. In the context of hydrazoic acid, the acid-base reaction can be simplified. When hydrazoic acid \(\mathrm{HN}_{3}\) donates a proton, the azide ion \(\mathrm{N}_{3}^{-}\) is formed. This transformation can be summarized as:\[\mathrm{HN}_{3} \rightarrow \mathrm{N}_{3}^{-} + \mathrm{H}^{+}\]Important points to consider about acid-base reactions include:

• Proton Transfer: Acids traditionally donate protons (\(\mathrm{H}^{+}\)), converting into conjugate bases.
• Reverse Reactions: The formed conjugate base \(\mathrm{N}_{3}^{-}\) can potentially act as a base in subsequent reactions.
• Conservation: Overall charge and the number of atoms are conserved in such reactions, reflecting the balance of nature.

This reaction is a clear example of the simplicity yet significance of such proton exchange processes, laying the groundwork for understanding more complex chemical systems.

Proton Donation

Proton donation is a core aspect of understanding how acids behave. In any acid-base reaction, you can identify an acid by observing which species donates a proton. When hydrazoic acid \(\mathrm{HN}_{3}\) donates a proton, an azide ion \(\mathrm{N}_{3}^{-}\) results, representing its conjugate base.

• This process highlights the ability of an acid to release hydrogen ions.
• The proton donation effectively lowers the concentration of hydrogen ions in the original acid.
• It impacts the pH and reactivity of the solution, dictating further reactions.

In essence, this simple act of proton donation defines the very nature of acids. It's this transfer that distinguishes acids from bases, where each resulting species plays a new role based on its residual charge and chemical potential. Understanding proton dynamics is critical for grasping broader concepts in chemistry, such as buffer solutions and the pH scale.