Sodium+hypochlorite

Sodium hypochlorite

Sodium hypochlorite is a chemical compound with the formula NaOCl. Sodium hypochlorite solution, commonly known as bleach or Clorox, is frequently used as a disinfectant or a bleaching agent.



Sodium hypochlorite was first produced in 1789 by Claude Louis Berthollet in his laboratory on the quay Javel in Paris, France, by passing chlorine gas through a solution of sodium carbonate. The resulting liquid, known as "//Eau de Javel//" ("Javel water"), was a weak solution of sodium hypochlorite. However, this process was not very efficient, and alternative production methods were sought. One such method involved the extraction of chlorinated lime (known as bleaching powder) with sodium carbonate to yield low levels of available chlorine. This method was commonly used to produce hypochlorite solutions for use as a hospital antiseptic that was sold under the trade names "Eusol" and "Dakin's solution". Near the end of the nineteenth century, E. S. Smith patented a method of sodium hypochlorite production involving electrolysis of brine to produce sodium hydroxide and chlorine gas, which then mixed to form sodium hypochlorite. This is known as the chloralkali process. Both electric power and brine solution were in cheap supply at the time, and various enterprising marketers took advantage of the situation to satisfy the market's demand for sodium hypochlorite. Bottled solutions of sodium hypochlorite were sold under numerous trade names. Today, an improved version of this method, known as the Hooker process, is the only large scale industrial method of sodium hypochlorite production. In the process, sodium hypochlorite (NaClO) and sodium chloride (NaCl) are formed when chlorine is passed into cold and dilute sodium hydroxide solution. It is prepared industrially by electrolysis with minimal separation between the anode and the cathode. The solution must be kept below 40 °C (by cooling coils) to prevent the undesired formation of sodium chlorate. Cl 2 + 2 NaOH → NaCl + NaOCl + H 2 O Hence, chlorine is simultaneously reduced and oxidized; this process is known as disproportionation. The commercial solutions always contain significant amounts of sodium chloride (common salt) as the main by-product, as seen in the equation above.
 * Production **

Include bleaching, disinfection, water treatment, endodontics, oxidation, and nerve agent neutralization.
 * Common Uses**

Safety
Sodium hypochlorite is a strong oxidizer. Oxidation reactions are corrosive, solutions burn skin and cause eye damage, in particular, when used in concentrated forms. However, as recognized by the NFPA, only solutions containing more than 40% sodium hypochlorite by weight are considered hazardous oxidizers. Solutions less than 40% are classified as a moderate oxidizing hazard (NFPA 430, 2000). Chlorination of drinking water can oxidize organic contaminants, producing trihalomethanes (also called haloforms), which are carcinogenic. Household bleach and pool chlorinator solutions are typically stabilized by a significant concentration of lye (caustic soda, NaOH) as part of the manufacturing reaction. Skin contact will produce caustic irritation or burns due to defatting and saponification of skin oils and destruction of tissue. The slippery feel of bleach on skin is due to this process. Trichloramine, the gas that is in swimming pools can cause atopic asthma. Sodium thiosulfate (thio) is an effective chlorine neutralizer. Rinsing with a 5 mg/L solution, followed by washing with soap and water, quickly removes chlorine odor from the hands. Mixing bleach with some household cleaners can be hazardous. For example, mixing an acid cleaner with sodium hypochlorite bleach generates chlorine gas. Mixing with ammonia solutions (including urine) produces chloramines. Mixtures of other cleaning agents and or organic matter can result in a gaseous reaction that can cause acute lung injury.