How does Bleach Work

Bleach has become an indispensable part of every household for its various uses. It plays an active role as a disinfectant and also as a whitening agent. Nowadays, the cosmetic uses of bleach have become so popular that people use various products to bleach the teeth, to lighten the skin color, to change the hair color. Whatever may be the use, the basic mechanism is bleaching.

Types of Bleach

Most common types include chlorine bleach and oxygen bleach. While the former is a solution of sodium hypochlorite, the latter contains hydrogen peroxide or a peroxide-releasing compound. Bleaching powder is nothing other than calcium hypochlorite. Some of the organic peroxides like benzoyl peroxide, are used to bleach flour, whereas some others are used as maturing agents in the food industry. Peracetic acid is used to bleach wood pulp in order to make newsprint. Most bleaches are oxidizing agents, but there are some which act as reducing agents. In spite of its various uses, there are many people who do not know how does bleach work.

Working Mechanism

• Bleach is widely used as a disinfectant, as it can destroy pathogens very efficiently and quickly. This feature is more prominent in sodium hypochlorite. Let us take a closer look at how does bleach kill bacteria. The action of bleach against microbes is as follows: The proteins in bacteria clump together, as they come in contact with bleach. This is done by the heat shock protein in bacteria, which tries to form lumps in order to protect other proteins in their body. This leads to the eventual death of the bacteria. The same principle is adopted by the human body, which produces hypochlorous acid to kill bacteria in case of any infection.
• Another common use of bleach is based on its whitening properties. Color is produced by molecules which contain chromophores and bleach works upon these molecules to achieve the whitening effect. Oxidizing bleach breaks down the molecules with chromophores and make them incapable of absorbing any visible light, while reducing bleach converts the double-bonded chromophore to single-bonded, thus making them incapable of absorbing visible light. The same principle is behind the bleaching action of sunlight. The high energy photons of light affects the bonds of chromophores, which in turn results in the gradual fading of color.

Even though the bleaching agents differ as per the context of usage, the working principles are same. Chlorinated water is one classic example of the usage of chlorine bleach. Chlorine is added to kill the germs and make the water safe for drinking. While some bleaches are very strong, others are mild, and are used as household bleach. The strong ones should be handled gently to avoid any harm.