Problem 50 - A Complete Resource Book in Chemistry for JEE Main

Question

The gas \(\mathrm{O}_{3}\) (ozone) cannot oxidize (a) \(\mathrm{KI}\) (b) \(\mathrm{FeSO}_{4}\) (c) \(\mathrm{KMnO}_{4}\) (d) \(\mathrm{K}_{2} \mathrm{MnO}_{4}\)

Step-by-Step Solution

Answer

Ozone cannot oxidize \( \mathrm{KMnO}_4 \).

Step 1: Understand the Oxidizing Power of Ozone

Ozone (\( \mathrm{O}_3 \)) is a powerful oxidizing agent, which means it can add oxygen to other substances. It oxidizes substances by converting them to a higher oxidation state, often forming oxides.

Step 2: Analyze Each Option for Feasibility of Oxidation

Review each compound to determine if ozone can oxidize it: (a) \( \mathrm{KI} \) can be oxidized to \( \mathrm{I}_2 \). (b) \( \mathrm{FeSO}_4 \) can be oxidized to \( \mathrm{Fe}_2(\mathrm{SO}_4)_3 \). (c) \( \mathrm{KMnO}_4 \) is a strong oxidizing agent itself and cannot be oxidized further by ozone. (d) \( \mathrm{K}_2 \mathrm{MnO}_4 \) can be oxidized to \( \mathrm{KMnO}_4 \).

Step 3: Identify the Non-Oxidizable Compound

Based on the analysis, \( \mathrm{KMnO}_4 \) is already in its highest oxidation state as it contains manganate(VII), which is very stable. Hence, it cannot be oxidized further by ozone.

Key Concepts

Ozone as Oxidizing Agent

Ozone (Cmathrm{O}_3 5) is a very effective oxidizing agent used in various chemical reactions. An oxidizing agent is a substance that has the ability to oxidize other substances. This means it causes another substance to lose electrons. Ozone is unique because it can transfer oxygen atoms to substances, leading to their oxidation.
Ozone's power comes from its unstable structure, which readily breaks down to give an oxygen molecule (Cmathrm{O}_2 5) and a nascent oxygen atom. The nascent oxygen is extremely reactive, enabling ozone to initiate oxidation reactions. In chemistry, ozone can convert Cmathrm{KI} 5 to Cmathrm{I}_2 5 and Cmathrm{FeSO}_4 5 to Cmathrm{Fe}_2(Cmathrm{SO}_4)_3 5, highlighting its high oxidative potential.
Overall, the utility of ozone spans multiple industries, from water purification to bleaching processes. Understanding ozone's oxidizing properties helps chemists leverage its potential effectively.

Chemical Oxidation States

Oxidation states are numerical assignments to elements in a compound that reflect their ability to gain or lose electrons. These states help chemists understand the flow of electrons in a reaction. When a substance is oxidized, its oxidation state increases, indicating it has lost electrons.

• For example, iodine in Cmathrm{KI} 5 has an oxidation state of -1. When oxidized by ozone, its state changes to 0 in Cmathrm{I}_2 5, suggesting electron loss.
• In Cmathrm{FeSO}_4 5, iron (Cmathrm{Fe} 5) has an oxidation state of +2. When oxidized to Cmathrm{Fe}_2(Cmathrm{SO}_4)_3 5, it becomes +3, again indicating electron loss.

Understanding oxidation states is vital for predicting the outcome of chemical reactions and determining which substances will be oxidized in the presence of an oxidizing agent like ozone.

KMnO4 Stability

Potassium permanganate, Cmathrm{KMnO}_4 5, is renowned for its stability, especially in high oxidation states. The manganate ion within Cmathrm{KMnO}_4 5 is in its highest oxidation state: +7.
This stability arises due to the robust structure of the permanganate ion, preventing further oxidation. It acts as a strong oxidizing agent itself and is commonly used in redox reactions.
As an oxidizing agent, Cmathrm{KMnO}_4 5 plays a role in a variety of chemical processes, including organic synthesis and water treatment due to its capability of transferring oxygen species to other compounds while remaining unaffected by oxidizing agents like ozone.
The stability of Cmathrm{KMnO}_4 5 is essential for its practical applications because it reliably maintains its oxidative potential without an external oxidizing influence.

Oxidizing Agents Comparison

Comparing oxidizing agents involves looking at their electron accepting abilities and where they can trigger oxidation in other substances. Different agents offer variable oxidizing strengths.

• Ozone (Cmathrm{O}_3 5) is a very potent oxidizer, which can act effectively in various conditions to increase the oxidation state of different compounds.
• Cmathrm{KMnO}_4 5 is another powerful oxidizing agent, widely used in analytical chemistry for titration based on its ability to maintain a high and stable oxidation state.

The effectiveness of these agents depends on the specific substances they are interacting with. While ozone can oxidize many simple compounds and change their oxidation states, Cmathrm{KMnO}_4 5 involves more complex reactions often requiring specific conditions. The choice of oxidizing agent relies on the desired outcome and available reaction conditions.