Question

Which of the following statements regarding hydrogen peroxide is false? (a) It is a strong oxidising agent. (b) It is decomposed by \(\mathrm{MnO}_{2}\). (c) It behaves as a reducing agent. (d) It is more stable in basic solution.

Short answer

Statement (d) is false, as hydrogen peroxide is more stable in acidic solutions, not basic ones.

Step-by-step solution

Understanding the Properties of Hydrogen Peroxide

To solve this question, review the properties of hydrogen peroxide (H2O2). We know that hydrogen peroxide behaves as both an oxidizing and a reducing agent in various reactions. It can be decomposed by catalysts such as manganese dioxide (MnO2). Its stability is also affected by pH levels.

Evaluating Each Statement

Assess each provided statement to determine if it aligns with the known properties of hydrogen peroxide: (a) True, hydrogen peroxide is used as a strong oxidizing agent due to its ability to accept electrons. (b) True, hydrogen peroxide can be decomposed by catalysts such as manganese dioxide (MnO2). (c) True, it can also act as a reducing agent in some reactions. (d) This statement requires verifying the stability of hydrogen peroxide in different pH solutions.

Identifying the False Statement

Examine the stability of hydrogen peroxide in acidic and basic solutions. Hydrogen peroxide is more stable in acidic solutions, not basic ones. Therefore, statement (d) is false because it incorrectly claims hydrogen peroxide is more stable in basic solutions.

Key concepts

Oxidising Agent

Hydrogen peroxide (H₂O₂) is widely recognized as a potent oxidizing agent, a chemical that can accept electrons from other substances during a reaction. It has a variety of applications, from disinfecting wounds to treating wastewater.

Oxidizing agents are essential in chemical reactions because they spur the transfer of electrons, facilitating a process called oxidation. H₂O₂ demonstrates this by decomposing to form water and oxygen, releasing energy and oxidizing the other reactants. Its ability to act as an oxidizing agent underpins many of its industrial uses, such as bleaching in paper and textile manufacturing.

Catalytic Decomposition

The decomposition of hydrogen peroxide can be sped up by the presence of a catalyst, such as manganese dioxide (MnO₂). Catalysts lower the activation energy required for a reaction, increasing the rate at which hydrogen peroxide breaks down into water (H₂O) and oxygen (O₂).

This process is catalytic decomposition, a reaction where a catalyst provides an alternative pathway for the reaction without being consumed itself. It has practical significance in biological systems where enzymes act as natural catalysts for the breakdown of H₂O₂, a byproduct of metabolism that could otherwise be harmful.

Reducing Agent

Contrastingly, hydrogen peroxide can also play the opposite role as a reducing agent in some chemical reactions - where it donates electrons to other substances. Whenever H₂O₂ acts in this capacity, it is reduced, typically forming oxygen or water as a result.

Its role as a reducing agent is equally as significant in chemical processes, particularly in reactions where metals are extracted from ores or pollutants are removed from industrial discharges. As a reducing agent, H₂O₂ helps gain metals in pure form by reducing metal oxides.

pH Level Stability

The stability of hydrogen peroxide is markedly influenced by the solution’s pH level. While it is relatively more stable in acidic conditions, its stability decreases in basic or alkaline solutions.

In acidic environments, H₂O₂ tends to be more stable because the excess protons (H⁺) in solution can help stabilize the peroxide ion (O₂^2-), which slows down its decomposition. On the other hand, in alkaline conditions, the lack of available protons promotes the decomposition process, making it less stable. Therefore, to maintain its potency, H₂O₂ is often stored in slightly acidic solutions.