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How does Bleach Work

Bleach is widely used for cleaning and whitening clothes. Go through this story for a brief overview about the working mechanism of bleach.
Sonia Nair
Nowadays, bleach is found as a common household item with numerous uses. It plays an active role as a disinfectant and also as a whitening agent. Certain types of bleach are used for lightening the skin, whitening teeth and lighten hair color. The basic function of a bleach is bleaching.
Chlorine bleach and oxygen bleach are the two common types of 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.

Working Mechanism

As a Disinfectant

Bleach is widely used as a disinfectant, as it can destroy pathogens, efficiently and quickly. This feature is more prominent in sodium hypochlorite. 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 proteins in bacteria, which try 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.

As a Whitening Agent

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; while reducing bleach converts the double-bonded chromophores to single-bonded.
In both cases, the chromophores become incapable of absorbing visible light and this results in lightening or whitening. The same principle is behind the bleaching action of sunlight. The high energy photons of sunlight affect the bonds of chromophores, which in turn, results in the gradual fading of color.
Even though the bleaching agents differ with the type of use, the working principles are almost similar. 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 for household purposes. The strong ones should be handled carefully, to avoid any harm.