Problem 3 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Among statements (A)-(D), the correct ones are: (A) Decomposition of hydrogen peroxide gives dioxygen. (B) Like hydrogen peroxide, compounds, such as \(\mathrm{KClO}_{3}, \mathrm{~Pb}\left(\mathrm{NO}_{3}\right)_{2}\) and \(\mathrm{NaNO}_{3}\) when heated liberate dioxygen. (C) 2-Ethylanthraquinone is useful for the industrial preparation of hydrogen peroxide. (D) Hydrogen peroxide is used for the manufacture of sodium perborate. (a) (A) (B), (C) and (D) (b) (A), (B) and (C) only (c) (A), (C) and (D) only (d) (A) and (C) only

Step-by-Step Solution

Answer

Option (a) is correct: (A), (B), (C), and (D).

Step 1: Analyze Statement A

Statement (A) claims that decomposition of hydrogen peroxide gives dioxygen. The decomposition reaction is as follows: \[ 2H_2O_2 \rightarrow 2H_2O + O_2 \]. Here, dioxygen \((O_2)\) is indeed a product, hence statement (A) is correct.

Step 2: Analyze Statement B

Statement (B) suggests that compounds like \(KClO_3\), \(Pb(NO_3)_2\), and \(NaNO_3\) release dioxygen when heated. This is true because these compounds usually decompose by releasing \(O_2\): \(2KClO_3 \rightarrow 2KCl + 3O_2\), \(2Pb(NO_3)_2 \rightarrow 2PbO + 4NO_2 + O_2\), and \(2NaNO_3 \rightarrow 2NaNO_2 + O_2\). Therefore, statement (B) is correct.

Step 3: Analyze Statement C

Statement (C) states that 2-ethylanthraquinone is useful for industrial preparation of hydrogen peroxide. This is correct as the anthraquinone process involves using 2-ethylanthraquinone as a catalyst for producing \( H_2O_2 \). Thus, statement (C) is correct.

Step 4: Analyze Statement D

Statement (D) states that hydrogen peroxide is used for the manufacture of sodium perborate. This is true, as \( H_2O_2 \) is commonly utilized in the chemical synthesis of sodium perborate, a bleaching agent. Hence, statement (D) is correct.

Step 5: Determine Correct Answer

Since all statements (A), (B), (C), and (D) are correct, option (a) (A), (B), (C), and (D) is the right answer.

Key Concepts

Decomposition Reaction

In chemical terms, a decomposition reaction is a type of reaction where a single compound breaks down into two or more simpler substances. It's like taking apart a block tower—you start with one structure, and end up with many pieces. One of the most common examples is the decomposition of hydrogen peroxide (H₂O₂), where it splits into water (H₂O) and oxygen gas (O₂).
Here's how the reaction works:

• The chemical equation for this decomposition is: \[ 2H_2O_2 \rightarrow 2H_2O + O_2 \]
• This reaction may sound simple, but it's very important. The release of oxygen is crucial in both laboratory and industrial applications.
• It often requires the presence of a catalyst, such as manganese dioxide (MnO₂), to speed up the reaction.

This type of reaction is not only essential for understanding chemical processes but also has practical applications like creating oxygen in confined spaces like submarines or space stations.

Dioxygen Release

The term dioxygen refers to a molecule consisting of two oxygen atoms, represented by the chemical formula O₂. In the context of decomposition reactions, dioxygen release is a significant process. When hydrogen peroxide decomposes, one of the products is dioxygen.
Why is the release of dioxygen important?

• Oxygen is a vital gas for sustaining life, making this reaction significant in various biological and environmental systems.
• Dioxygen release is employed industrially for tasks like bleaching and waste treatment.

Interestingly, other compounds such as potassium chlorate (\(KClO_3\)), lead nitrate (\(Pb(NO_3)_2\)), and sodium nitrate (\(NaNO_3\)) can also release dioxygen upon heating. These reactions often require heat or a catalyst to proceed, releasing oxygen which can then be utilized for combustion or oxidation processes.

Industrial Use in Chemistry

In the industrial world, hydrogen peroxide isn't just a simple household bleach. It's a significant player in various large-scale chemical processes. For instance, the production of hydrogen peroxide involves an industrial method known as the anthraquinone process.
Here's how it works:

• The anthraquinone process uses 2-ethylanthraquinone as a catalyst to produce hydrogen peroxide.
• This method is favored because it allows for the continuous production of hydrogen peroxide on a large scale.
• Industrially produced hydrogen peroxide is used for bleaching textiles, paper, and even food. It also finds applications in environmental control and chemical synthesis.

The ability to produce hydrogen peroxide efficiently and safely on an industrial scale has made it an invaluable chemical in many areas beyond household cleaning products.

Chemical Synthesis

Chemical synthesis refers to the purposeful execution of chemical reactions to obtain a product, or several products. Among these synthesized chemicals, sodium perborate stands out due to its wide application as a bleaching agent.
Hydrogen peroxide plays a crucial role in this process:

• Sodium perborate is manufactured by reacting sodium metaborate with hydrogen peroxide.
• This compound is commonly found in laundry detergents and cleaning products.

The reaction is an excellent example of how hydrogen peroxide is utilized beyond simple decomposition, becoming an integral part of various chemical syntheses. Understanding its role in synthesis emphasizes the breadth of applications hydrogen peroxide has in both everyday and industrial chemistry.