Problem 44 - A Complete Resource Book in Chemistry for JEE Main

Question

The \(\mathrm{Na}^{+}\)present in \(\mathrm{NaCl}\) is (a) acidic radical (b) basic radical (c) neutral radical (d) none of these

Step-by-Step Solution

Answer

The \( \mathrm{Na}^{+} \) in \( \mathrm{NaCl} \) is a basic radical.

Step 1: Understanding the Problem

We need to classify the nature of the \( \mathrm{Na}^{+} \) ion present in \( \mathrm{NaCl} \) as either acidic, basic, neutral, or none.

Step 2: Define Radical Types

A radical can be acidic if it typically dissociates to provide \( \mathrm{H}^{+} \) ions in water, basic if it typically dissociates to provide \( \mathrm{OH}^{-} \) ions, and neutral if it does not affect the \( \text{pH} \) of a solution.

Step 3: Analyze \( \mathrm{NaCl} \) Dissociation

Sodium chloride dissociates in water to form \( \mathrm{Na}^{+} \) and \( \mathrm{Cl}^{-} \) ions. Neither of these ions releases \( \mathrm{H}^{+} \) or \( \mathrm{OH}^{-} \), meaning they do not directly alter the \( \text{pH} \) of the solution.

Step 4: Identify \( \mathrm{Na}^{+} \) Characteristic

The \( \mathrm{Na}^{+} \) ion does not contribute \( \mathrm{H}^{+} \) or \( \mathrm{OH}^{-} \) ions; hence it is neither acidic nor basic. It pairs with \( \mathrm{Cl}^{-} \) to form neutral compounds like \( \mathrm{NaCl} \).

Step 5: Determine the Right Answer

Since \( \mathrm{Na}^{+} \) does not affect \( \text{pH} \) and forms a neutral compound with chloride, it is a basic radical according to convention, because it is a positive ion formed from a metal.

Key Concepts

Acidic Radicals

Acidic radicals are typically related to the components that lead to the formation of an acid when combined with hydrogen ions. They tend to dissociate in water and produce hydrogen ions (\( \mathrm{H}^+ \)), leading to a decrease in the pH of a solution.

Some common examples of acidic radicals include:

• Sulphate (\( \mathrm{SO}_4^{2-} \))
• Nitrate (\( \mathrm{NO}_3^- \))
• Chloride (\( \mathrm{Cl}^- \))

When these ions form compounds and dissolve in water, they usually help release hydrogen ions, making the solution acidic.

Overall, acidic radicals are non-metal ions or negative ions that help form acids and typically decrease the pH of a solution when dissociated.

Basic Radicals

Basic radicals originate from bases and are usually associated with the release of hydroxide ions (\( \mathrm{OH}^- \)) in water, leading to an increase in pH. These radicals are typically derived from metal elements and are positive ions.

Examples include:

• Sodium (\( \mathrm{Na}^+ \))
• Potassium (\( \mathrm{K}^+ \))
• Calcium (\( \mathrm{Ca}^{2+} \))

Such ions do not release hydroxide ions directly, but when they combine with hydroxide ions in a compound, they show basic behavior.

In the case of sodium (\( \mathrm{Na}^+ \)) in sodium chloride (\( \mathrm{NaCl} \)), the \( \mathrm{Na}^+ \) ion does not alter the pH of the solution significantly on its own. However, by convention, it is still considered a basic radical because it originates from a metal that can form bases.

Neutral Radicals

Neutral radicals are neither acidic nor basic and tend to have little to no effect on the pH of a solution when dissolved in water. These radicals do not dissociate to release either hydrogen (\( \mathrm{H}^+ \)) or hydroxide (\( \mathrm{OH}^- \)) ions.

Examples of neutral radicals might include certain complex ions or radicals in specific contexts, but typically:

• Inert gases
• Certain organic molecules

These entities neither contribute to acidity nor to basicity in a solution.

It is important to identify the role of each radical in a chemical reaction to understand its properties fully. Although some radicals might seem neutral in a specific context, their behavior needs to be assessed based on their interactions with other compounds.