sodium hypochlorite sodium hypochlorite sodium hypochlorite names iupac name sodium hypochlorite other names antiforminbleachchloride of sodain dilution:carrel-dakin solutionmodified dakin's solutionsurgical chlorinated soda solution identifiers cas number 7681-52-9 (anhydrous) y10022-70-5 (pentahydrate) y 3d model (jsmol) interactive image chebi chebi:32146 y chemspider 22756 y drugbank dbsalt001517 echa infocard 100.028.790 ec number 231-668-3 kegg d01711 y pubchem cid 23665760 rtecs number nh3486300 unii dy38vhm5od y un number 1791 comptox dashboard (epa) dtxsid8021276 inchi inchi=1s/clo.na/c1-2;/q-1;+1 ykey: sukjfigyrhowbl-uhfffaoysa-n yinchi=1/clo.na/c1-2;/q-1;+1key: sukjfigyrhowbl-uhfffaoyad smiles .cl properties chemical formula naocl molar mass 74.442 g/mol appearance greenish-yellow solid (pentahydrate) odor chlorine-like and sweetish density 1.11 g/cm3 melting point 18 °c (64 °f; 291 k) pentahydrate boiling point 101 °c (214 °f; 374 k) (decomposes) solubility in water 29.3 g/100ml (0 °c) acidity (pka) 7.5185 basicity (pkb) 6.4815 thermochemistry std enthalpy offormation (δfh⦵298) -347.1 kj/mol pharmacology atc code d08ax07 (who) hazards occupational safety and health (ohs/osh): main hazards oxidizer, corrosive ghs labelling: pictograms signal word danger hazard statements h302, h314, h410 precautionary statements p260, p264, p273, p280, p301+p330+p331, p303+p361+p353, p304+p340, p305+p351+p338, p310, p321, p363, p391, p405, p501 nfpa 704 (fire diamond) 2 0 1ox safety data sheet (sds) icsc 1119 (solution, >10% active chlorine)icsc 0482 (solution, <10% active chlorine) related compounds other anions sodium chloridesodium chloritesodium chloratesodium perchlorate other cations lithium hypochloritecalcium hypochloritepotassium hypochlorite related compounds hypochlorous acid except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references sodium hypochlorite, commonly known in a dilute solution as (chlorine) bleach, is an inorganic chemical compound with the formula naocl (or naclo), comprising a sodium cation (na+) and a hypochlorite anion (ocl−or clo−). it may also be viewed as the sodium salt of hypochlorous acid. the anhydrous compound is unstable and may decompose explosively. it can be crystallized as a pentahydrate naocl·5h2o, a pale greenish-yellow solid which is not explosive and is stable if kept refrigerated. sodium hypochlorite is most often encountered as a pale greenish-yellow dilute solution referred to as liquid bleach, which is a household chemical widely used (since the 18th century) as a disinfectant or a bleaching agent. in solution, the compound is unstable and easily decomposes, liberating chlorine, which is the active principle of such products. sodium hypochlorite is the oldest and still most important chlorine-based bleach. its corrosive properties, common availability, and reaction products make it a significant safety risk. in particular, mixing liquid bleach with other cleaning products, such as acids found in limescale-removing products, will produce chlorine gas, which was used as a chemical weapon in world war i. a common urban legend states that mixing bleach with ammonia also releases chlorine, but in reality the two chemicals react differently, producing chloramines and/or nitrogen trichloride. with excess ammonia and sodium hydroxide, hydrazine may be generated. chemistry stability of the solid anhydrous sodium hypochlorite can be prepared but, like many hypochlorites, it is highly unstable and decomposes explosively on heating or friction. the decomposition is accelerated by carbon dioxide at atmospheric levels. it is a white solid with the orthorhombic crystal structure. sodium hypochlorite can also be obtained as a crystalline pentahydrate naocl·5h2o, which is not explosive and is much more stable than the anhydrous compound. the formula is sometimes given as 2naocl·10h2o.. the cl–o bond length in the pentahydrate is 1.686 å. the transparent, light greenish-yellow, orthorhombic crystals contain 44% naocl by weight and melt at 25–27 °c. the compound decomposes rapidly at room temperature, so it must be kept under refrigeration. at lower temperatures, however, it is quite stable: reportedly only 1% decomposition after 360 days at 7 °c. a 1966 us patent claims that stable solid sodium hypochlorite dihydrate naocl·2h2o can be obtained by carefully excluding chloride ions (cl−), which are present in the output of common manufacturing processes and are said to catalyze the decomposition of hypochlorite into chlorate (clo−3) and chloride. in one test, the dihydrate was claimed to show only 6% decomposition after 13.5 months storage at −25 °c. the patent also claims that the dihydrate can be reduced to the anhydrous form by vacuum drying at about 50 °c, yielding a solid that showed no decomposition after 64 hours at −25 °c. equilibria and stability of solutions at typical ambient temperatures, sodium hypochlorite is more stable in dilute solutions that contain solvated na+ and ocl− ions. the density of the solution is 1.093 g/ml at 5% concentration, and 1.21 g/ml at 14%, 20 °c. stoichiometric solutions are fairly alkaline, with ph 11 or higher since hypochlorous acid is a weak acid: ocl− + h2o ⇌ hocl + oh− the following species and equilibria are present in naocl/nacl solutions: hocl (aq) ⇌ h+ + ocl− hocl (aq) + cl− + h+ ⇌ cl2 (aq) + h2o cl2 (aq) + cl− ⇌ cl−3 cl2 (aq) ⇌ cl2 (g) the second equilibrium equation above will be shifted to the right if the chlorine cl2 is allowed to escape as gas. the ratios of cl2, hocl, and ocl− in solution are also ph dependent. at ph below 2, the majority of the chlorine in the solution is in the form of dissolved elemental cl2. at ph greater than 7.4, the majority is in the form of hypochlorite clo−. the equilibrium can be shifted by adding acids (such as hydrochloric acid) or bases (such as sodium hydroxide) to the solution: clo− (aq) + 2 hcl (aq) → cl2 (g) + h2o (aq) + cl− (aq) cl2 (g) + 2 oh− → clo− (aq) + cl− (aq) + h2o (aq) at a ph of about 4, such as obtained by the addition of strong acids like hydrochloric acid, the amount of undissociated (nonionized) hocl is highest. the reaction can be written as: clo− + h+ ⇌ hclo sodium hypochlorite solutions combined with acid evolve chlorine gas, particularly strongly at ph < 2, by the reactions: hocl (aq) + cl− + h+ ⇌ cl2 (aq) + h2o cl2 (aq) ⇌ cl2 (g) at ph > 8, the chlorine is practically all in the form of hypochlorite anions (ocl−). the solutions are fairly stable at ph 11–12. even so, one report claims that a conventional 13.6% naocl reagent solution lost 17% of its strength after being stored for 360 days at 7 °c. for this reason, in some applications one may use more stable chlorine-releasing compounds, such as calcium hypochlorite ca(clo)2 or trichloroisocyanuric acid (cnclo)3. anhydrous sodium hypochlorite is soluble in methanol, and solutions are stable. decomposition to chlorate or oxygen in solution, under certain conditions, the hypochlorite anion may also disproportionate (autoxidize) to chloride and chlorate: 3 clo− + h+ → hclo3 + 2 cl− in particular, this reaction occurs in sodium hypochlorite solutions at high temperatures, forming sodium chlorate and sodium chloride: 3 naocl (aq) → 2 nacl (aq) + naclo3 (aq) this reaction is exploited in the industrial production of sodium chlorate. an alternative decomposition of hypochlorite produces oxygen instead: 2 ocl− → 2 cl− + o2 in hot sodium hypochlorite solutions, this reaction competes with chlorate formation, yielding sodium chloride and oxygen gas: 2 naocl (aq) → 2 nacl (aq) + o2 (g) these two decomposition reactions of naclo solutions are maximized at ph around 6. the chlorate-producing reaction predominates at ph above 6, while the oxygen one becomes significant below that. for example, at 80 °c, with naocl and nacl concentrations of 80 mm, and ph 6–6.5, the chlorate is produced with ∼95% efficiency. the oxygen pathway predominates at ph 10. this decomposition is affected by light and metal ion catalysts such as copper, nickel, cobalt, and iridium. catalysts like sodium dichromate na2cr2o7 and sodium molybdate na2moo4 may be added industrially to reduce the oxygen pathway, but a report claims that only the latter is effective. titration titration of hypochlorite solutions is often done by adding a measured sample to an excess amount of acidified solution of potassium iodide (ki) and then titrating the liberated iodine (i2) with a standard solution of sodium thiosulfate or phenylarsine oxide, using starch as indicator, until the blue color disappears. according to one us patent, the stability of sodium hypochlorite content of solids or solutions can be determined by monitoring the infrared absorption due to the o–cl bond. the characteristic wavelength is given as 140.25 μm for water solutions, 140.05 μm for the solid dihydrate naocl·2h2o, and 139.08 μm for the anhydrous mixed salt na2(ocl)(oh). oxidation of organic compounds oxidation of starch by sodium hypochlorite, that adds carbonyl and carboxyl groups, is relevant to the production of modified starch products. in the presence of a phase-transfer catalyst, alcohols are oxidized to the corresponding carbonyl compound (aldehyde or ketone). sodium hypochlorite can also oxidize organic sulfides to sulfoxides or sulfones, disulfides or thiols to sulfonyl halides, imines to oxaziridines. it can also de-aromatize phenols. oxidation of metals and complexes heterogeneous reactions of sodium hypochlorite and metals such as zinc proceed slowly to give the metal oxide or hydroxide: naocl + zn → zno + nacl homogeneous reactions with metal coordination complexes proceed somewhat faster. this has been exploited in the jacobsen epoxidation. other reactions if not properly stored in airtight containers, sodium hypochlorite reacts with carbon dioxide to form sodium carbonate: 2 naocl + co2 + h2o → na2co3 + 2 hocl sodium hypochlorite reacts with most nitrogen compounds to form volatile monochloramine, dichloramines, and nitrogen trichloride: nh3 + naocl → nh2cl + naoh nh2cl + naocl → nhcl2 + naoh nhcl2 + naocl → ncl3 + naoh neutralization sodium thiosulfate is an effective chlorine neutralizer. rinsing with a 5 mg/l solution, followed by washing with soap and water, will remove chlorine odor from the hands. production chlorination of soda potassium hypochlorite was first produced in 1789 by claude louis berthollet in his laboratory on the quai de javel in paris, france, by passing chlorine gas through a solution of potash lye. the resulting liquid, known as "eau de javel" ("javel water"), was a weak solution of potassium hypochlorite. antoine labarraque replaced potash lye by the cheaper soda lye, thus obtaining sodium hypochlorite (eau de labarraque). cl2 (g) + 2 naoh (aq) → nacl (aq) + naclo (aq) + h2o (aq) hence, chlorine is simultaneously reduced and oxidized; this process is known as disproportionation. the process is also used to prepare the pentahydrate naocl·5h2o for industrial and laboratory use. in a typical process, chlorine gas is added to a 45–48% naoh solution. some of the sodium chloride precipitates and is removed by filtration, and the pentahydrate is then obtained by cooling the filtrate to 12 °c . from calcium hypochlorite another method involved the reaction of sodium carbonate ("washing soda") with chlorinated lime ("bleaching powder"), a mixture of calcium hypochlorite ca(ocl)2, calcium chloride cacl2, and calcium hydroxide ca(oh)2: na2co3 (aq) + ca(ocl)2 (aq) → caco3 (s) + 2 naocl (aq) na2co3 (aq) + cacl2 (aq) → caco3 (s) + 2 nacl (aq) na2co3 (aq) + ca(oh)2 (s) → caco3 (s) + 2 naoh (aq) this method was commonly used to produce hypochlorite solutions for use as a hospital antiseptic that was sold after world war i under the names "eusol", an abbreviation for edinburgh university solution of (chlorinated) lime – a reference to the university's pathology department, where it was developed. electrolysis of brine near the end of the nineteenth century, e. s. smith patented the chloralkali process: a method of producing sodium hypochlorite involving the electrolysis of brine to produce sodium hydroxide and chlorine gas, which then mixed to form sodium hypochlorite. the key reactions are: 2 cl− → cl2 + 2 e− (at the anode) 2 h2o + 2 e− → h2 + 2 ho− (at the cathode) 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 (named after hooker chemicals, acquired by occidental petroleum), 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 dilute sodium hydroxide solution. the chlorine is prepared industrially by electrolysis with minimal separation between the anode and the cathode.