Problem 64 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is the strongest oxidizing agent? (a) \(\mathrm{F}_{2}\) (b) \(\mathrm{Cl}_{2}\) (c) \(\mathrm{Br}_{2}\) (d) \(\mathrm{I}_{2}\)

Step-by-Step Solution

Answer

The strongest oxidizing agent is \\(\\mathrm{F}_{2}\\).

Step 1: Understanding Oxidizing Agents

An oxidizing agent gains electrons and is reduced in the process. Stronger oxidizing agents have a higher tendency to gain electrons.

Step 2: Analyzing the Halogens

The halogens in the problem are \(\text{F}_{2}\), \(\text{Cl}_{2}\), \(\text{Br}_{2}\), and \(\text{I}_{2}\). In general, the strength of oxidizing agents follows the trend down the group: \(\text{F}_2 > \text{Cl}_2 > \text{Br}_2 > \text{I}_2\), with fluorine being the strongest.

Step 3: Conclusion Based on Electron Affinity

Fluorine \(\text{F}_2\) has the highest electron affinity among the halogens, making it the most powerful oxidizing agent because it effectively attracts electrons.

Key Concepts

Halogens

Halogens are a group of elements found in Group 17 of the periodic table. These elements include fluorine (\( \text{F}_2 \)), chlorine (\( \text{Cl}_2 \)), bromine (\( \text{Br}_2 \)), and iodine (\( \text{I}_2 \)). Halogens are well-known for being highly reactive, especially with metals to form salts. They exist as diatomic molecules, meaning they form molecules consisting of two atoms.
The reactivity of halogens decreases as you move down the periodic table. This is because elements higher up in the group, like fluorine, have greater electronegativity and can attract electrons more effectively.

• Fluorine is the most reactive of the halogens.
• Chlorine, bromine, and iodine follow in decreasing reactivity.

When discussing oxidizing power, fluorine (\( \text{F}_2 \)) is the strongest among these, due to its high tendency to attract electrons.

Electron Affinity

Electron affinity refers to the energy change that occurs when an electron is added to a neutral atom in the gaseous state, forming a negative ion. It is a measure of an atom's ability to attract and hold onto electrons, which plays a significant role in its capacity as an oxidizing agent.
Elements with high electron affinity have a strong attraction for electrons and are thus more effective oxidizing agents.

• Fluorine has the highest electron affinity, which means it is very effective at attracting electrons and forming an ion.
• As we move down the group, electron affinity generally decreases.

The high electron affinity of fluorine makes it the most powerful oxidizing agent among the halogens, demonstrating its ability to gain electrons efficiently.

Reduction Process

The reduction process involves the gain of electrons by an atom, ion, or molecule. In this context, oxidizing agents are substances that bring about reduction because they themselves gain electrons.
During a chemical reaction involving oxidizing and reducing agents, the oxidizing agent undergoes reduction.

• In the case of halogens, they gain electrons to form negative ions.
• Fluorine, for instance, gains an electron to form the fluoride ion, \( \text{F}^- \).

Understanding the reduction process is crucial for determining the strength of oxidizing agents. Stronger oxidizing agents, like fluorine, are more readily reduced, making them more efficient at oxidizing other substances.