Problem 20 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The oxide that gives hydrogen peroxide on treatment with a dilute acid is (a) \(\mathrm{PbO}_{2}\) (b) \(\mathrm{Na}_{2} \mathrm{O}_{2}\) (c) \(\mathrm{MnO}_{2}\) (d) \(\mathrm{TiO}_{2}\)

Step-by-Step Solution

Answer

(b) \(\mathrm{Na}_{2}\mathrm{O}_{2}\)

Step 1: Understanding the Problem

The problem asks which of the given metal oxides will produce hydrogen peroxide when treated with a dilute acid. To solve this, we need to know the chemical reactions and properties of the oxides listed.

Step 2: Analyzing the Options

The given options are: (a) \(\mathrm{PbO}_{2}\), (b) \(\mathrm{Na}_{2} \mathrm{O}_{2}\), (c) \(\mathrm{MnO}_{2}\), and (d) \(\mathrm{TiO}_{2}\). Sodium peroxide, \(\mathrm{Na}_{2} \mathrm{O}_{2}\), is known for reacting with water and acids to release hydrogen peroxide.

Step 3: Chemical Reaction Explanation

When \(\mathrm{Na}_{2} \mathrm{O}_{2}\) reacts with a dilute acid like \(\mathrm{HCl}\), it forms hydrogen peroxide. The reaction is as follows: \[\mathrm{Na}_{2} \mathrm{O}_{2} + 2\mathrm{HCl} \rightarrow 2\mathrm{NaCl} + \mathrm{H}_2\mathrm{O}_2\]. This indicates \(\mathrm{Na}_{2} \mathrm{O}_{2}\) is the correct oxide.

Step 4: Exclusion of Other Options

\(\mathrm{PbO}_{2}\), \(\mathrm{MnO}_{2}\), and \(\mathrm{TiO}_{2}\) do not produce hydrogen peroxide when reacted with dilute acids. These compounds do not have the oxidation states and properties compatible with the production of \(\mathrm{H}_2\mathrm{O}_2\).

Key Concepts

Hydrogen Peroxide Formation

Hydrogen peroxide (\( \mathrm{H}_2\mathrm{O}_2 \)) is a versatile chemical with various applications, ranging from bleaching agents to disinfectants.
It is known for containing an oxygen-oxygen single bond, which is a bit unstable, allowing it to decompose into water and oxygen.
Hydrogen peroxide can be formed through chemical reactions involving specific metal oxides and acids.

• One common method is through the reaction of sodium peroxide (\( \mathrm{Na}_2 \mathrm{O}_2 \)) with dilute acids.
• In this reaction, the acidic environment facilitates the breaking of bonds in the metal oxide, leading to the formation of \( \mathrm{H}_2\mathrm{O}_2 \).

Recognizing the specific metal oxides that can generate hydrogen peroxide upon treatment with acids is essential in various chemical processes.

Metal Oxides Reactions

Metal oxides are compounds composed of metal elements and oxygen.
The way they react depends largely on the metal's reactivity and the oxide's structure.

• For instance, the oxide \( \mathrm{Na}_2 \mathrm{O}_2 \) can react with acids to produce hydrogen peroxide. This specific reaction occurs because the sodium ions interact with the acidic environment, allowing them to release \( \mathrm{H}_2\mathrm{O}_2 \).
• Other oxides, like \( \mathrm{PbO}_2 \) or \( \mathrm{MnO}_2 \), do not interact similarly and won't produce hydrogen peroxide when mixed with dilute acids. These compounds often have bonds and structures that are less conducive to such reactions.

Understanding how different metal oxides react is pivotal, especially in industrial processes where byproducts like hydrogen peroxide play significant roles.

Sodium Peroxide

Sodium peroxide \( \mathrm{Na}_2\mathrm{O}_2 \) is a reactive metal oxide, known particularly for its ability to release hydrogen peroxide in chemical reactions.
It is characterized by a combination of sodium ions and peroxide ions.
When sodium peroxide is introduced to moisture or diluted acids, it readily decomposes, releasing hydrogen peroxide.

• For example, in the presence of water or dilute hydrochloric acid \( \mathrm{HCl} \), it forms \( \mathrm{NaCl} \) and \( \mathrm{H}_2\mathrm{O}_2 \).
• This reaction is crucial in instances where a stable source of \( \mathrm{H}_2\mathrm{O}_2 \) is required, given the sensitivity of the peroxide group to decomposition.

The ability of sodium peroxide to generate hydrogen peroxide efficiently makes it invaluable in various scientific and industrial applications, such as in bleaching and sterilization processes.