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My mother just forwarded an email to all her contacts (thanks, mom), warning us of the dangers of mixing Lysol and bleach together. Here's most the content, translated from French:

Bleach and Lysol, a lethal mix

If the experience of my friend can be of any help... Read her email!

Here is my latest bad experience that I want to share with you. It might be useful to you. On January 2nd 2011, I was finishing to wash the previous evening's dishes when I had family come over for dinner. As I was finishing, I thought of using a bit of bleach to disinfect the sink.

Since I had very little bleach left, I went to fetch my Lysol and poured the bleach I had left with the Lysol. This was a terrible mix that you should never attempt to recreate. Two minutes later, I could barely breathe and thirty minutes later I was at the hospital where I received care from the ambulance and at the hospital.

The doctor told me that it would have taken very little more for me pass away. An accident by lack of knowledge can happen quite fast and can sometimes be lethal.

As a general rule, I'm skeptical of whatever I read in chain mails so I googled excerpts of the text. Unsurprisingly, I found an almost exact match as the first search result. The only difference is that the year changed, from 2011 in the email I received to 2009 on the blog page so it's undoubtedly a chain letter. By the way, that page is also the first result when you google "eau de javel lysol" ("bleach lysol", in French).

A search on the web returns unhelpful results, with the average content farms contradicting each other and offering no trustworthy source.

As any chemist would know, bleach is sodium hypochlorite and, from a quick search, it would seem the active agent in Lysol is benzalkonium chloride but I can't find anything on the interaction of those two compounds either. From a quick look at the two compounds, I would be surprised to see any spectacular interaction between the two of them though.

So, does anyone know what happens when you mix Lysol and bleach?

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I don't have the chemistry background to comment on the question at hand, but I'll say this: that's a lovely chain letter! Hey guys I did something rather weird and unlikely, and now I must make it my mission to warn everyone. I think I'll email all of my friends and tell them not to eat silica gel. –  David Hedlund Mar 1 '11 at 18:54
    
@DavidHedlund: Kudos to the author for understanding that fear is a potent force which will ensure that, three years after he or she wrote the email, people will still be spammed by it. –  Borror0 Mar 1 '11 at 19:03
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The entire text of the warning letter could be substituted by the message "Don't be an idiot". –  Zano Nov 22 '11 at 13:23
    
Lysol does actually contain ammonium saccharinate which will produce dealy fumes if mixed with sodium hypochlorite –  user14036 Jun 2 '13 at 20:32

2 Answers 2

up vote 23 down vote accepted

According to this document from the NJ health department: Common Cleaning Products May Be Dangerous When Mixed, dangerous gasses are produced.

More generally, The Chlorine Institute, Inc. advises that one not "mix Sodium Hypochlorite (bleach) with ANY other chemical unless adequate engineering controls and personal protective equipment (PPE) are in place" in their Avoiding Accidental Mixing of Sodium Hypochlorite document. They also have a Sodium Hypochlorite Incompatibility Chart (English Version) which lists the bad things which can happen when mixing bleach with other chemicals.

Thanks to Fabian in the comments, he noted that benzalkonium chloride is a quarternary ammonium salt which, according to the incompatibility chart, will release chlorine or other noxious gases when mixed.

Additionally, according to the makers of Lysol ( Reckitt Benckiser Inc. ) in their Material Safety Data Sheet, they say "DO NOT MIX WITH BLEACH" - note the nice big bold letters.

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As far as I found, Lysol contains neither ammonia nor acid, so those reactions don't explain this specific case. –  Fabian Mar 1 '11 at 19:08
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The linked incompatibility chart explains it, as benzalkonium chloride is a quarternary ammonium salt, which is listed in that chart. –  Fabian Mar 1 '11 at 19:15
                              H2O + Cl2 ↔ HCl + HClO

This is the basic reaction of Chlorine in water: the production of hydrogen chloride and hypochloric acid. To keep this solution stable, you can make the solution very alkaline, to have Cl- and ClO- ions, normally with Na+ as a counterion. Just the latest, NaClO, is sodium hypochlorite, which is commonly known as bleach.

The reason why you should never mix bleach with other cleaning liquids is that they

  1. may contain chlorine ions, which would introduce back the Cl- in the solution
  2. change the pH to acid, or altering the solubility (e.g. introducing ethanol, or adding other components that may alter the chemical activity of the participants above).

This would allow the essential components of the reaction given above to be present in solution, and then through the reverse reaction promote release of Cl2, which is a nasty gas.

Hence, I restate the obvious. Do not, any under circumstance, mix bleach with other detergents. I've done it in the lab, I knew what I was doing, and it still ended up a mess.

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"and it still ended up a mess" - Do you have a blog? I'd like to hear that story. =P –  BrightUmbra Mar 10 '11 at 19:03
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Boo =( hehe –  BrightUmbra Mar 14 '11 at 12:25
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What molecule is the "chlorine" smell we notice around indoor swimming pools? –  Ed Brannin Dec 18 '11 at 19:26
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This was written before our stringent demands for referencing. It could do with a cite or two. –  Oddthinking Oct 9 '12 at 2:26
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@Oddthinking Benzalkonium Chloride is probably more Acidic than the Bleach though, which is sufficient to cause a reaction. A useful rule of thumb is to never mix an opaque bottle with a transparent bottle. Since bleach reacts with UV light it is normally kept in opaque bottles. –  Nick Dec 10 '12 at 19:08

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