Question

How does ${{H}_{2}}{{O}_{2}}$ behave as a bleaching agent?

Answer 1

Hint: Bleaching process is the same as oxidation. Hydrogen Peroxide (${{H}_{2}}{{O}_{2}}$) is a colorless liquid, resembling water in many properties. It has physical properties very similar to that of water.

Complete step by step solution:

${{H}_{2}}{{O}_{2}}$ or hydrogen peroxide acts as a strong oxidizing agent in both acidic and basic mediums. The single bond present between the two oxygen atoms is weak, Therefore, it readily separates into either H and $H{{O}_{2}}$ or two OHs, resulting in formation of free radicals meaning they are very reactive. Thus, ${{H}_{2}}{{O}_{2}}$ is a very powerful oxidizing agent.The dissociation can be written as
${{H}_{2}}{{O}_{2}}~\left( aq \right)\to {{H}^{+}}+{{O}_{2}}{{H}^{-}}$

Due to this reason ${{H}_{2}}{{O}_{2}}$ can be used as a bleaching agent. The high oxidizing ability of ${{H}_{2}}{{O}_{2}}$ enables it to react directly with large molecules having double bonds, and form organic peroxides. These double bonds are often the reason that causes the molecules to absorb light, and give the molecule its color. Now upon removal of them destroys the pigments and so removes the color. Hence, giving it a white appearance. ${{H}_{2}}{{O}_{2}}$ is commonly used as a bleach wood pulp to make white paper, and to remove the melanin in hair, giving the blonde effect to hair.

Note: ${{H}_{2}}{{O}_{2}}$ is a very strong oxidizing agent, therefore, generally a concentration of only 3% in water is sold. This makes it much safer to handle, but still it slowly starts reacting with the water and decomposing. And in direct sunlight, decomposition occurs even faster. Therefore, it should be stored in cool places, in dark brown glass bottles.