question: How does bleach whitten things like mold or clothes?
comment: Washing bleach contains Hypocloric acid, which acts as a very strong oxidizer. It works by oxidizing dye agents in the stains so that they become colorless. It preferentially attacks dyes since strongly colored organic chemicals often have conjugated double carbon bonds.
passages: Textile bleaching is one of the stages in the manufacture of textiles. All raw textile materials, when they are in natural form, are known as 'greige' material. This greige material will have its natural color, odor and impurities that are not suitable for clothing materials. Not only the natural impurities will remain on the greige material but also the add-ons that were made during its cultivation, growth and manufacture in the form of pesticides, fungicides, worm killers, sizes, lubricants, etc. The removal of these natural coloring matters and add-ons during the previous state of manufacturing is called scouring and bleaching.
   Section::::Bleaching chemical pulps.:Chelant wash.
   Bleaches generally react with many other organic substances besides the intended colored pigments, so they can weaken or damage natural materials like fibers, cloth, and leather, and intentionally applied dyes such as the indigo of denim. For the same reason, ingestion of the products, breathing of the fumes, or contact with skin or eyes can cause health damage.
  
  Section::::History.
   Section::::Bleaching chemical pulps.:Ozone.
   Section::::Other media.
   Section::::Media.
  
  Section::::Media.:Manga.
   Section::::Scouring.
  
  Scouring is the first process carried out with or without chemicals, at room temperature or at suitable higher temperatures with the addition of suitable wetting agents, alkali and so on. Scouring removes all the waxes, pectins and makes the textile material hydrophilic or water absorbent. See also scouring wool.
  
  Section::::Bleaching.
  
  The next process of decolorization of greige material into a suitable material for next processing is called bleaching. Bleaching of textiles can be classified into oxidative bleaching and reductive bleaching.
  
  Section::::Bleaching.:Oxidative bleaching.
   US Government regulations (21 CFR Part 178) allow food processing equipment and food contact surfaces to be sanitized with solutions containing bleach, provided that the solution is allowed to drain adequately before contact with food, and that the solutions do not exceed 200 parts per million (ppm) available chlorine (for example, one tablespoon of typical household bleach containing 5.25% sodium hypochlorite, per gallon of water).
   Section::::Plot.
   It is used as such in some industrial dyeing processes to eliminate excess dye, residual oxide, and unintended pigments and for bleaching wood pulp.
  
  Reaction of sodium dithionite with formaldehyde produces Rongalite, 
  
  which is used in bleaching wood pulp, cotton, wool, leather and clay.
  
  Section::::Environmental impact.
   Liquid bleach
  
  Liquid bleach, often called just bleach, is a common chemical household product that consists of a dilute solution of sodium hypochlorite () and other secondary ingredients. It is a chlorine releasing bleaching agent widely used as a to whiten clothes and remove stains, as a disinfectant to kill germs, and for several other uses.
  
  While the term has had that meaning for a long time, it may now be applied more generically to any bleaching agent for laundry in liquid form, irrespective of its composition; such as some peroxide-based bleaches.
  
  Section::::History.
   In some cases, the textiles are weakened not by outside causes such as light or pests, but by chemical reactions taking place within the fabric itself, such as the oxidation of iron-based mordants over time, which can cause darkening and discolouration in the surrounding fibres.
   Bleaching is a process for whitening fabrics which has been practiced for thousands of years. Sometimes it was simply a matter of leaving the fabric in the sun, to be faded by the bright light. In the 18th century several scientists developed varieties of chlorine bleach, including sodium hypochlorite and calcium hypochlorite (bleaching powder). Bleaching agents that do not contain chlorine most often are based on peroxides, such as hydrogen peroxide, sodium percarbonate and sodium perborate. While most bleaches are oxidizing agents, a fewer number are reducing agents such as sodium dithionite.
   Section::::Plot.
   Section::::Components.:Bleaches.
  
  The main targets of bleaches are oxidisible organic stains; which are usually of vegetable origin (e.g. chlorophyll, anthocyanin dyes, tannins, humic acids, and
   Section::::Media.:Video games.
   Delignification of chemical pulps is frequently composed of four or more discrete steps, with each step designated by a letter in the Table:
   Section::::Disinfection.
  
  Sodium hypochlorite solution, 3–6%, (common household bleach) is typically diluted for safe use when disinfecting surfaces and when used to treat drinking water.
  
  A weak solution of 2% household bleach in warm water is typical for sanitizing smooth surfaces prior to brewing of beer or wine.
   Section::::Controversy.
   Chlorine-based bleaches are found in many household "bleach" products, as well as in specialized products for hospitals, public health, water chlorination, and industrial processes. 
  
  The grade of chlorine-based bleaches is often expressed as percent active chlorine. One gram of a 100% active chlorine bleach has the same bleaching power as one gram of elemental chlorine. 
  
  The most common chlorine-based bleaches are:
   Caustic soda is added to increase the pH in the pulping process of fibers. The higher pH of the paper-fiber solution causes the fibers to smoothen and swell, which is important for the grinding process of the fibers.
  
  Section::::Bleaching.
  
  In the production of white paper, the wood pulp is bleached to remove any color from the trace amounts of lignin that was not extracted in the chemical pulping process. There are three predominant methods of bleaching:
  
  BULLET::::1. Elemental chlorine bleaching uses chlorine and hypochlorite.
   Section::::In other media.:Film.
   Potassium hypochlorite () was synthesized by French scientist Berthollet in 17??, by reacting chlorine gas () with a solution of potassium hydroxide (potash, ). He also discovered its cloth bleaching properties, and set out to commercialize it under the name of "Eau de Javel" ("water of Javel") after the borough of Paris where it was manufactured. It was the first product intended specifically for that application, and it shortened the process of bleaching newly made cloth from months to hours.
   The presence of other organic matter in the place of application can make these disinfectants less effective, by consuming some of the released chlorine.
  
  Section::::Uses.:Whitening agents.
  
  Chlorine-based bleaches have been used since the late 18th century to whiten cotton and linen clothes, removing either the natural fiber color or stains of sweat or other organic residues. They are still used in households for laundry and to remove organic stains (such as mildew) on surfaces.
   Section::::Themes.
  