Talk:Sodium hypochlorite

Hydrolysis or electrolysis?
"Near the end of the nineteenth century, E. S. Smith patented a method of hypochlorite production involving hydrolysis of brine to produce caustic soda and chlorine gas, which then mixed to form hypochlorite.[citation needed] Both electric power and brine solution were in cheap supply at this time, and various enterprising marketers took advantage of this situation to satisfy the market's demand for hypochlorite."

Maybe electrolysis? It looks like a misprint. --159.148.226.100 (talk) 20:08, 6 March 2011 (UTC)

As no one has commented this I will now edit, preserving "hydrolysis" as comment. "citation needed" tag was already present. --159.148.226.100 (talk) 07:25, 8 March 2011 (UTC)

I think Hydrolysis is the correct term.Longinus876 (talk) 11:56, 12 May 2015 (UTC)


 * "Electrolysis" is definitely the correct term (fixed). Sodium chloride cannot "hydrolize" that way without considerable energy input.  Heating or other chemical methods will not do it.  --Jorge Stolfi (talk) 19:56, 12 June 2018 (UTC)

Reaction with Alcohols
In undergrad labs we used NaOCl and reacted it with glacial acetic acid to form HOCl which maintains an equilibrium between HOCl and H2OCl+ (The H2O will not form a leaving group because the chloride ion does not have the electrons required to leave) which can oxidize alcohols to carbonyls without the use of a catalyst. I don't have a source for this other than a powerpoint presentation I can still access from my universities lab website though. Figure this would be important to add since it is not even mentioned on the hypochlorous acid page, but this page mentions the use of NaOCl to oxidize alcohols to carbonyls. I've only used it to form ketones but I imagine it works with aldehydes Kasooi (talk) 21:51, 30 July 2011 (UTC)

Chemical States
I am not a frequent contributor, so I won't make the changes myself, but I feel like the reactions section would greatly benefit from giving the chemical state of each reagent (ie: (g), (s), (l), (aq)...). This would clarify the reactions shown for better layperson understanding of what the products of some of these reactions are. — Preceding unsigned comment added by 76.115.177.0 (talk) 20:56, 25 March 2012 (UTC)

Hooker process
Hooker process should link to this page, if it doesn't get it's own stub. ~ender 2012-05-26 9:58:AM MST — Preceding unsigned comment added by 98.165.52.42 (talk)

General information for introductory paragraph
There appears to be significant omissions from the introduction. Basic characteristics like electrophilic, basic and so on are not even hinted at. As a chemical, surely these kind of attributes should be outlined in the introduction. It just jumps straight into production, before any brief synopsis of usage aswell. To me this seems poor. There are many wiki article which include information like this in the introductions like Hydrocholirc acid:
 * http://en.wikipedia.org/wiki/Hydrochloric_acid

or sodium chloride:
 * http://en.wikipedia.org/wiki/Sodium_chloride

Would someone who is more confident with the chemistry and usage of sodium hypochlorite please sort this? 90.193.233.41 (talk) 14:20, 29 August 2012 (UTC)

Boiling point and decomposition temp
The article currently gives a boiling point for NaOCl of 101°C. However the "Handbook of Preparative Inorganic Chemistry" 2nd Ed. by G. Brauer (page 309) would imply that for the pentahydrate, decomposition to NaCl and NaClO3 takes place anywhere above 0°C. Obviously household bleach is stable above this temperature, so dilution is clearly a factor, but a stability of 101°C seems very high. Most of the literature on stability is in relation to endodontics and doesn't discuss solutions above 5%. Does anyone have access to better references? Project Osprey (talk) 12:04, 11 September 2013 (UTC)
 * I hope this point is clear now. The anhydrous form is unstable and explosive. Unfortunately I could not access the papers where it is (presumably) described.  The pentahydrate melts at about 25°C to give a water solution; I don't think that it makes sense to specify its boiling point.  --Jorge Stolfi (talk) 07:01, 13 June 2018 (UTC)

Production: Electrolysis
I understand that the "same reactants" can yield different results: ethanol + sulfuric acid = {ethylene, diethyl ether} depending on temperature. But the entries for sodium hypochlorite sodium chlorate and sodium perchlorate all pretty much say that they're created the same way. Can someone knowledgeable on this topic put in the differentiating conditions? — Preceding unsigned comment added by 68.32.223.91 (talk) 02:13, 29 September 2014 (UTC) — Preceding unsigned comment added by 68.32.223.91 (talk)


 * The conditions are different. (Emphasis added)
 * From Sodium hypochlorite: (The Hooker process)
 * In the process, sodium hypochlorite (NaClO) and sodium chloride (NaCl) are formed when chlorine is passed into cold and dilute sodium hydroxide solution. The solution must be kept below 40 °C (by cooling coils) to prevent the undesired formation of sodium chlorate.
 * Cl2 + 2 NaOH → NaCl + NaClO + H2O
 * From Sodium chlorate:
 * Industrially, sodium chlorate is produced by the electrolysis of a hot sodium chloride solution:
 * NaCl + 3 H2O → NaClO3 + 3 H2
 * This reaction progresses in heat (at least 70 degrees Celsius), and controlled pH.
 * From Sodium perchlorate:
 * Sodium perchlorate is produced by anodic oxidation of sodium chlorate, not sodium chloride, at an inert electrode, such as platinum.
 * ClO3&minus;(aq) + H2O(l) → ClO4&minus;(aq) + H2(g)
 * I hope this helps. Tomásdearg92 (talk) 10:09, 30 September 2014 (UTC)

storage of household bleach
"Household bleach sold for use in laundering clothes is a 3–8% solution of sodium hypochlorite at the time of manufacture. Strength varies from one formulation to another and gradually decreases with long storage."

This is very practical, helpful information. It would be even better if it indicated how fast the concentration declines with time under typical household storage conditions (months-years) and what variables may influence this the most. Storage in glass vs. plastic? How tight the lid is? Temperature? And it would be good to have the physical-chemical details of what is happening over time - what chemicals are being produced, in what forms and what concentrations? (Some readers will have in hand a partial container of bleach which has sat neglected for years, wanting to understand what is likely to be inside now.)-71.174.183.177 (talk) 20:21, 13 February 2015 (UTC)
 * Please see what Wikipedia is not. Wikipedia is not intended to provide exhaustive information on the degredation of household chemicals, their storage, safety or disposal. Anything resembling a how-to guide or medical advice is strongly advised against. If you or any others have a theoretical question to ask, you can always ask it at the Reference Desk. Tomásdearg92 (talk) 16:40, 15 February 2015 (UTC)

Concentrations and significant figures
I'm going to explain my thinking here, in accordance with WP:BRD. I think the range 5500-6530 ppm suggests bounds that are not really as rigid as is implied.

Note the following from the CDC Disinfection Guideline: "The most prevalent chlorine products in the United States are aqueous solutions of 5.25%–6.15% sodium hypochlorite [...] a 1:10 dilution of household bleach provides about 5250–6150 ppm." User:PAR rightly pointed out that there are three significant figures in the given concentration range, but there is only one in "1 part to 9 parts water", and it's a stretch to say there are two in "1:10 dilution".

In addition, it is implicitly acknowledged that there are other concentrations of bleach, this range only considers the US and doesn't take into account PAR's 5% correction. The aim is not to create a solution which is exactly 0.525% hypochlorite (except in the case of the HPV paper where reproducibility matters), the aim is to make a solution that is approximately 0.5% (as in the instruction poster).

I'm reinserting a more approximate number, not because I'm thick-headed and don't want to discuss, but because I'm reorganising the sentences in this section and don't know how else to write it. Tomásdearg92 (talk) 22:58, 29 August 2017 (UTC)


 * I was concerned about people trying to calculate things, and coming up with numbers that don't match. I was going crazy trying to calculate things based on various formulas and unsupported statements, and having the numbers not match. This was due to various approximations (e.g. forget about the 5% correction, forget about density variations, estimate density of solution as the density of water, etc. etc.) I wrote the "relationship to free chlorine" section to lay out the math without approximations. I didn't list the approximations that could be made, maybe I should, but as long as the math in this section is not wiped out in favor of some approximation, I'm ok. I just went back to the rest of the article and tried to give better answers, worrying that people were going to do the calculation, come up with different numbers, and wonder why. As long as the approximate results you use are explained as an approximation, I'm ok. PAR (talk) 03:30, 19 September 2017 (UTC)

Ant scent trails
Mention that bleach is often used to wipe out ant scent trails. Plenty of references in Google. Jidanni (talk) 11:23, 6 October 2017 (UTC)

Hydrazine risk and possible original contents
The following material was in bleach safety section, as one of the risks of mixing bleach and ammonia:
 * Additional reactions produce hydrazine, in a variation of the Olin Raschig process.
 * Additional reactions produce hydrazine, in a variation of the Olin Raschig process.


 * NH3 + NH2Cl + NaOH → N2H4 + NaCl + H2O


 * The hydrazine generated can react with more chloramine in an exothermic reaction to produce ammonium chloride and nitrogen gas:


 * 2 NH2Cl + N2H4 → 2 NH4Cl + N2


 * However, the place of atomic oxygen in accounting for the formation of chlorine is not as plausible as another theory based on the so-called 'chloride system' employed in modern hydrometallurgy to dissolve ores with weak acids in highly ionic and concentrated salt solutions. Salts particularly effective, in this regard, include MgCl2, CaCl2, FeCl3 and, to a lesser extent, the mono-valent NaCl. This is, in effect, an application of the non-common ion theory, or as discussed in Wikipedia under Solubility Equilibrium as the 'salt effect'. With respect to bleaching powder, which has been described as a compound salt of the form, the presence of CaCl2 in very concentrated solutions can greatly increase the 'activity level' of weak acids. So, in this particular proposed application, H2CO3 from CO2 and moisture on the bleaching powder, acts on the CaCl2 to release some HCl which acts on the HClO releasing Chlorine:


 * HClO + HCl → H2O + Cl2


 * or, the increasing acidity creates more HClO which moves the following known (and old, see Watt's Dictionary of Chemistry) equilibrium reaction to the right:


 * CaCl2 + 2 HClO Ca(OH)2 + 2 Cl2

I wonder whether the hydrazine synthesis really can occur by mixing naOCl and ammonia, and whether it is a real health risk. I cannot make much sense of the rest of that material. Since no reference was given, it is possible that it is original research. Could someone please clarify? --Jorge Stolfi (talk) 03:27, 11 June 2018 (UTC)


 * Here's a reliable source: https://www.doh.wa.gov/YouandYourFamily/HealthyHome/Contaminants/BleachMixingDangers
 * It doesn't specifically mention hydrazine but does explain why it isn't a good idea to mix ammonia with bleach or acids.
 * The formula above appears in the abstract of this scientific paper: https://pubs.acs.org/doi/pdf/10.1021/ja01148a061
 * So I don't think it's really original research; it's just unsourced. ~Anachronist (talk) 03:44, 11 June 2018 (UTC)

Melting point of pentahydrate: 18 or 25-27?
The previous version of the infobox and many webpages like PubChem give the melting point of ·5 as "18 °C". However, the journal papers that describe the compound and announce its availability as a research/industrial chemical say "25–27 °C". Which is right? The commercial product contains some NaCl and NaOH, but those impurities should lower the MP, right? --Jorge Stolfi (talk) 02:48, 13 June 2018 (UTC)

NaClO or NaOCl?
Google says that "NaOCl" is about twice as popular as "NaClO", so I put both in the head. Which one shoudl go in the infobox? Which one should be used in the body of the article? --Jorge Stolfi (talk) 07:05, 13 June 2018 (UTC)

Other hydrates?
This page and this one are the only references I found to a supposed "2.5 hydrate" or "2:2:5 hydrate", 2·5, supposedly with CAS number 55248-17-4. This other page shows a monohydrate, with that same CAS number 55248-17-4. Is either of these two pages correct? --Jorge Stolfi (talk) 05:50, 15 June 2018 (UTC)

Also, This page and this one give 10022-70-5 as the CAS number of the petahydrate. instead of 7681-52-8. Bogus or real? --Jorge Stolfi (talk) 05:55, 15 June 2018 (UTC)

Anhydrous product available in alcohol solution?
This article says "[...] sodium hypochlorite anhydrous alcohol, and other chemical reagents (all of them were analytic grade) were obtained from The Development Center of Chemical Agents in Tianjin.". Is that reagent really available, of is that a typo by the authors? Supposedly alcohols and hyochlorites should not be mixed, right? --Jorge Stolfi (talk) 05:44, 15 June 2018 (UTC)

Please update Chembox
Dear, Please update the hazards section with GHS data. EU Class has been outdated Thanks Agung.karjono (talk) 08:43, 31 March 2020 (UTC)


 * Hi @Agung.karjono, why can you not do it? We need every possible resource here. If it is outdated, update the links or correct what needs to be corrected. KR 17387349L8764 (talk) 21:05, 14 April 2021 (UTC)

Sodium_hypochlorite_washes
Hi, stumbled across https://en.wikipedia.org/wiki/Sodium_hypochlorite_washes, just wondering if anyone wants to review it. Is it a thing at all? Article seems to have references and looks overall Ok to me. I work on something else right now. Greetings. 17387349L8764 (talk) 21:04, 14 April 2021 (UTC)

Merge Sodium hypochlorite washes -> Sodium hypochlorite
, please don't propose a merge on two pages if you aren't willing to start a merge discussion. The other article has problems, but it is so distinct from the main topic that it would be unwise to merge them, in my opinion. You can always send it to AFD. Dennis Brown - 2&cent; 19:00, 26 May 2021 (UTC)
 * Closing, with no merge, given the uncontested objection and no support. Klbrain (talk) 15:17, 3 October 2021 (UTC)

Reaction with ammonia
The article states "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 or ammonia, will produce chlorine gas, a poison gas used in World War I." I would delete this paragraph firstly because the reaction of ammonia and sodium hypochlorite won't produce chlorine. It will rather produce monochloramine which reacts with ammonia to produce hydrazine. Other chloramines will maybe also form but probably no chlorine. The products are still toxic. Secondly further down in the article the risk of unwanted chlorine release by mixing bleach with other cleaning products is mentioned again. HanTrio (talk) 16:57, 3 July 2021 (UTC)


 * I agree with this. Question, though: are you saying that bleach reacts with ammonia to produce monochloramine, which THEN reacts with MORE of the ammonia to create hydrazine?  Can you break down the reaction for me?  Thanks!  A loose necktie (talk) 20:22, 12 September 2021 (UTC)

Decomposition to chlorate or oxygen: an inconsistency?
In section "Decomposition to chlorate or oxygen", there is this sentence: "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.[20] ". It sounds inconsistent to me. First it says the oxygen producing reaction becomes significant at pH equal to, or below, 6. Then it says that the pathway leading to the production of oxygen predominates at pH 10. Perhaps there is something I am not able to understand.Ekisbares (talk) 16:40, 30 January 2022 (UTC)

Ahh, someone already complained about it before me. Darsie42 (talk) 18:58, 8 February 2022 (UTC)

Safety reference contradicts the statement
The reference for the statement about asthma nearly completely contradicts what actual sentence says.

"Chronic exposure, for example, from the air at swimming pools where chlorine is used as the disinfectant, can lead to the development of atopic asthma.[59]"

Articles says:

Children living in a house regularly cleaned with bleach were less likely to have asthma (OR, 0.10; CI, 0.02–0.51), eczema (OR, 0.22; CI, 0.06–0.79) and of being sensitized to indoor aeroallergens (OR, 0.53; CI, 0.27–1.02), especially house dust mite (OR, 0.43; CI, 0.19–0.99). These protective effects were independent of gender, ethnicity, previous respiratory infections, total serum IgE level and of family history of allergic diseases

I wonder if it's been altered by the antichemical brigade. 210.54.35.41 (talk) 23:45, 29 October 2022 (UTC)
 * It's more subtle than that (please WP:AGF unless you have actual evidence to the contrary). The ref states:
 * Our investigations on children attending indoor chlorinated swimming pools have shown that trichloramine, the gas giving swimming pools their characteristic smell, can damage the lung epithelium and promote the development of atopic asthma (10–12). Recently also, trichloramine has been found to induce asthma in lifeguards working in indoor swimming pools (13). Other studies focusing on occupational risks have demonstrated that women employed in domestic cleaning and using chlorine bleach have an elevated risk of respiratory diseases such as asthma and chronic bronchitis (14–16).
 * And the study does not contradict it. Instead, it distinguishes the effects of chemical byproducts of the cleaning (especially with poor ventilation) from the effects of things having been cleaned. By reading the Wikipedia article's sentence in its paragraph of context, the health concern is the nitrogen trichloride rather than NaOCl. DMacks (talk) 16:59, 29 August 2023 (UTC)

False synthesis pathway in ‘Production’ section
The methods from the ‘From ozone and salt’ subsection are not valid for sodium hypochlorite production. I was drawn to question the credibility of this information when reviewing the chemical formula provided. I was confident no such product would form. This information was further put into question with the absence of any citations. The stated reaction NaCl + O3 → NaClO + O2 suggests a direct reaction between sodium chloride and ozone to produce sodium hypochlorite and diatomic oxygen. However, this is not a commonly recognized or studied reaction pathway for the production of sodium hypochlorite, at least to my knowledge, and further confirmed in literature review online. Please refer to the work of Razumovskii et al.

“The decomposition of ozone in aqueous solutions of NaCl is not accompanied by the formation of products other than oxygen. In particular, no noticeable amounts of hypochlorites and chlorates are observed.” For the time being, I have removed this subsection. For reference, here is the particular [|revision version]

Ghostyseven (talk) 16:38, 29 August 2023 (UTC)


 * Good catch, and even better with a ref that directly disproves it. Might even be a useful ref for other articles. DMacks (talk) 16:42, 29 August 2023 (UTC)

Fearmongering statements in the article
I removed anything that sounded like fearmongering. It suggested that you'd more likely to get cancer if you mixed bleach with something! A very small amount of chloroform definitely will not give you cancer. ⲔⲖⲞⲢⲠⲒⲔⲢⲒⲚ (talk) 14:46, 4 February 2024 (UTC)