Question

\(\mathrm{H}_{2} \mathrm{O}_{2}\) acts as a bleaching agent because of (a) reducing nature of \(\mathrm{H}_{2} \mathrm{O}_{2}\) (b) oxidising nature of \(\mathrm{H}_{2} \mathrm{O}_{2}\) (c) acidic nature of \(\mathrm{H}_{2} \mathrm{O}_{2}\) (d) basic nature of \(\mathrm{H}_{2} \mathrm{O}_{2}\).

Short answer

Hydrogen peroxide (H2O2) acts as a bleaching agent primarily due to its oxidizing nature.

Step-by-step solution

Understanding the Chemical Property involved in Bleaching

The action of bleaching by a substance involves the removal of color from a material. For a substance to act as a bleaching agent, it must alter the structure of the color-causing compounds. One way to do this is through oxidation, which involves the gain of oxygen or loss of electrons.

Identifying the Role of H2O2 in Bleaching

Hydrogen peroxide, or H2O2, is known to be a strong oxidizing agent. It has the ability to take electrons from other substances or transfer oxygen to them, which can break the chemical bonds of the color-causing molecules, leading to decolorization.

Choosing the Correct Option

Given the oxidizing nature of hydrogen peroxide, which allows it to bleach other substances, the correct answer is its oxidizing nature.

Key concepts

Hydrogen Peroxide

Hydrogen peroxide (\textbf{H}\(_2\)\textbf{O}\(_2\)) is a clear, colorless liquid that functions as a powerful bleaching agent owing to its oxidizing properties. It's composed of hydrogen and oxygen, resembling water in its chemical structure but with an additional oxygen atom. This extra atom makes hydrogen peroxide highly reactive.

When it comes into contact with other substances, the loose bond of the additional oxygen atom can easily be broken, allowing it to react rapidly. This reactivity is harnessed in various applications, from disinfecting wounds to whitening teeth. In household concentrations, it is relatively safe, but at industrial strengths, it can be hazardous due to the potential release of large amounts of energy upon decomposition.

Chemical Properties of Bleaching Agents

Bleaching agents are chemicals that reduce or eliminate color from materials, such as fabrics or hair. The chemical properties that allow bleaching agents to perform their function include their reactivity to different molecules, especially pigments. These agents typically carry out their action through either an oxidation or a reduction process.

Oxidizing bleaches, like hydrogen peroxide, work by breaking the chemical bonds in chromophores – the part of molecules responsible for color. This changes the molecule so that it either no longer reflects light in the visible spectrum or it reflects light differently, thereby changing its apparent color. On the other hand, reducing bleaches add electrons to chromophores, a process that can alter the molecule's structure and make it colorless as well.

Key Factors in Bleaching:

• Chemical reactivity
• Ability to break down chromophores
• Mode of action (oxidation or reduction)

Oxidation-Reduction Reactions

Oxidation-reduction reactions, also known as redox reactions, are chemical processes where electrons are transferred between substances. Oxidation involves the loss of electrons, whereas reduction involves gaining electrons.

These reactions are fundamental in chemistry because they account for many significant changes in matter, such as combustion, corrosion, and indeed bleaching. In the context of bleaching, when hydrogen peroxide acts as an oxidizing agent, it donates oxygen to another substance or accepts electrons from them. This alters the molecular structure of the chromophores causing decolorization. The versatility of redox reactions is remarkable – they are the basis for the functioning of batteries, the browning of an apple, and even our metabolism.

Indicators of Redox Reactions Include:

• Change in color
• Energy release in the form of heat or light
• Formation of new substances