How does bleach remove stains?« Back to Questions List

Bleach is a chemical that can act as disinfectant and remove or lighten color. There are many types of bleaching agents depending on their application they are put to. Apart from whitening clothes, bleaches are used widely in medical and food industry too.


Chlorine bleach is widely used as disinfectant in hospitals to disinfect surgical tools, floor surfaces and labs. Food industry also uses it as a disinfectant to kill harmful bacteria. Chlorine bleach contains sodium hypochlorite (NaOCl). This chemical is added to water to make it safe for drinking by killing the typhoid-causing, cholera-causing bacteria.

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Oxygen bleach also acts to remove stains especially organic ones like coffee, tea, dirt, juices, blood, ketchup etc. This kind of bleach contains hydrogen peroxide and sodium percarbonate or sodium perboate. So how do these bleaches take the color out of the clothes? They work by oxidation or reduction reactions.

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Stains generally have strong double bonds. The molecules containing color are called chromophores. An oxidizing bleach acts by breaking the chemical bonds of these chromophores. Reducing bleaches changes the double bonds of the stains into single bond. The breaking of the bonds during oxidation or reduction reaction causes the color change, making them colorless.

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These chemical bleaches may prove harmful if not used properly. It should always be diluted before use. While bleaching surfaces, we must make sure there is enough ventilation because chlorine produces fumes. These fumes should not be inhaled as they may irritate the nasal passage, cause coughs and sore throats.