You might be right, but I’ll have to crunch some numbers to be sure. Two hundred p.p.m. available chlorine is what I generally shoot for when sterilizing something. That’s enough to kill even hard-shelled organisms such as cryptosporidium. I think a dishwasher is more on the order of two to three gallons, so a tablespoon should do it. Legal minimum for restaurant dishwashing here in Ventura County is 50 p.p.m., so 200 might easily be overkill, especially since we’re talking municipal tap water here, which has already been treated. The 200 p.p.m. figure is what I use when treating groundwater in the backcountry.
Most of this discussion seems to focus on the alkalinity of bleach. Is there a dioxin hazard to bleach and/or bleach residue?
I dated a girl who was housekeeping challenged when she first left home. She was told bleach killed anything germ-like (she even took a bath every so often in with 1 cup bleach added - which, other than the slight scent, was fine). She would leave the dishes and pots and pans soaking for 2 days or more sometimes. I noticed this was a bad idea when we tried using her double-boiler; it looked fine, but on close inspection we found the inner pot was leaking into the outer one through a few tiny pits that had eaten all the way through the pot.
So if you wash something with bleach, especially dilute, and rinse it off well, you should be fine. Give the reaction time, with several weeks of accumulated soaking, and you may not like the result.
The ammonia-and-bleach thing is a common story. I even recall it being the subject of a murder-made-to-look-like suicide story. “He was found dead the next morning in the bathroom. Who goes home drunk and tries to clean their toilet at 2 AM?”
Back when I was cleaning pools, there were always warnings not to pour in the chlorine and the acid simultaneously. This was around the time of Ghostbusters, and I thought of it as a warning not to cross the streams, or else the universe would end. In a big cloud of nerve gas.
Another note to make is that Chlorine bleach is hard to rinse off. It takes a lot of rinsing to really be rid of it. So even after you’ve washed a pot or some flatware it can be sitting int he cabinet reacting quietly and pitting away. This happened to me after washing and twice rinsing a SS kitchen sink. I came home from vacation to find it rough and ugly.
Bleach can pit stainless - here is info on how to fix it if it’s not too far gone:
http://www.howtobrew.com/appendices/appendixB-1.html
Sicne we’re on the subject, I saw on TV a lady recommending Clorox bleach as a tooth whitener. She poured a little on her toothbrush and used it normally. I guess if it’s truly a base this is not as problematic as I automatically assumed? (swallowing it, obviously would be.) But would it hurt the teeth or gums?
I had a co-worker who used to regularly use hydrogen peroxide as a mouth rinse to whiten her teeth. And it worked; her teeth were dazzling; but I always wondered what kind of damage she was doing to them (or her gums).
dentist here. probably no harm other than maybe some sensitivity, the tooth you get from the dentist and OTC such as Crest white strips is carbamide peroxide,about the same thing. Although I don’t now the concetration of hydrogen peroxide v. carbamide peroxide.
I will attempt to address the two keywords from your posting, with alkalinity having already been mentioned several times before with no previous definition of the term. If you’re not interested in chemistry then I would suggest moving on to the next posting.
Alkalinity is a measure primarily of the carbonate-bicarbonate-hydroxide-hydrogen (though borates, phosphates, silicates and other bases can contribute) equlibria in water (whether talking natural water bodies or water treatment or wastewater treatment). Most natural waters have pH values at or above a pH of 7 and are therefore “alkaline” and the quantification of the various ionic constituents is measured by titrating the samples to two pH endpoints:
[ul]8.3: this corresponds to the stochiometric neutralization of carbonic acid to bicarbonate and is sometimes referred to as phenolphthalein alkalinity since the colorimetric endpoint using this indicator is between a pH of 8.2-8.3
[/ul][ul]4.3-4.9: this value depends on whether the alkalinity is due to carbonate/bicarbonate or silicates/phosphates and also on the actual concentration range. It is normally referred to as “total alkalinity” though some older references can be found to “methyl orange alkalinity”.[/ul]
BTW - laboratory testing now uses actual pH measurement to a specified endpoint rather than the colorimetric indicators noted above.
In a broad sense alkalinity can be thought of as the ability of water to resist changes in pH and the actual quantification of ionic species can be determined by these two determinations along with initial sample pH.
It should also be pointed out that almost all commercial grade sodium hypochlorite (concentration ranging from 12-15 % by weight) has caustic soda (sodium hydroxide) added to help stabilize against the type of degradation discussed above. I do not know if “Clorox” has caustic stabilizers added or not since the greater the dilution of the bleach solution the less tendancy to “off-gassing”.
Dioxin, which by convention uses 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as the reference compound, actually consists of a broad class of Polychlorinated dibenzo-p-dioxins (PCDDs) and Polychlorinated dibenzofurans (PCDFs) (with some references lumping PCBs into the mix due to similarity of structure).
None of the dioxins would be expected to be present in any grades of sodium hypochlorite or bleach as the raw material for production is typically sodium chloride (or brine) solutions.
I’m not sure if your question regarding dixin may have had anything to do with the controversy associated with the use of chlorine compounds for disinfecting our public water supplies in the US but I am not aware that dioxin, or dioxin like compounds, are an issue with regard to the use of chlorine, hypochlorite, chloramine or other similar compounds. The focus on disinfection byproducts (DBPs) is on the total trihalomethanes (TTHMs) and the total haloacetic acids (TAA5s).
Bleach can chlorinate organics. I suspect it involves dissolved chlorine as an intermediate. Some of these byproducts may be dioxin like.
From memory, several commercial hypochlorite based formulations (as opposed to straight bleach) have been found to contain small amounts of chlorinated compounds. I suspect the risk is extremely low.
I stick with straight hypochlorite rather than the cleaner formulations. I also wear gloves and don’t use bleach regularly. Any place, including resteraunts and hospitals, that needs sanitation, should use bleach all of the time. There just is no commercial equivalent.
GAWD help me, Waterman, I UNDERSTOOD your post!
(and here I’ve thought for YEARS that all that kawlij edjumication just slid off my brain like I was made of Teflon…)
I even remembered what phenothlalein is!
~VOW
I read years ago–in a Time Life book, actually–that it’s the buildup of free O[sub]2[/sub], released in the second reaction, that actually provides the disinfectant action when you chlorinate a pool. Too much oxygen, so the book said, is lethal.
I’m not an expert on cleaning and disinfecting, but I am a chemist. So I gotta ask. Where’d you get the 200 ppm number?
Not doubting you, just curious. And googling gives me a thousand different answers from a thousand different sources of varying authority.
I did find a few sources that say a 1:100 dilution gives about 500 ppm, if that makes the envelope calculation quicker.
I was bored, decided to do the calc, and then saw that you did give a source. Sorry, 
My envelope calculation gives:
6% - household bleach NaOCl concentration
256 - tablespoons/gal
3 - gal/dishwasher cycle
So one tablespoon for a dishwasher cycle gives what, 78.125 ppm? Round it to 80 ppm.
If it’s 2 gal/dishwasher cycle you’d be at 117.1875, round to 120 ppm.
So I guess it is in the ballpark. I’m still :dubious: at 50 or 200 ppm NaOCl being an effective disinfectant; not because I have any actual knowledge, it just sounds dilute. But maybe that’s enough.
Vow you have made my day! A little off topic perhaps but let’s talk about phenolphthalein for a brief moment in an amusing anecdote.
When I was a freshman in college (don’t ask how long ago that was) several of my senior fraternity brothers stole some 95% ethyl alcohol from our school chem lab and thought they had struck the mother lode! They heartily drank it down without knowledge of the fact that the school had denatured the stuff. Well this could have been catastrophic if the school had used methyl alcohol or some other really nasty stuff to denature with but they chose to denature it with phenolphthalein! Which brings us to the second great use of phenolphthalein! Besides it’s use as an indicator in laboratories for acid-base titrations , it is (was) the main ingredient in Ex-Lax. You can imagine the fun-filled 12 hours that the two brothers had!!!
Washoe’s post is based on ppm of available chlorine not ppm of NaOCl. There is a difference and I’m not at work where I have my trusty tables listing available chlorine versus % NaOCl.
I don’t see how that’s possible. O2 does not dissolve in water in enough of an amount to disinfect. Now, O3 is a pretty powerful disinfectant and is used some water treatment processes.
Perhaps it did say ozone.
I’ve still got the book as a memento of the far-distant past when Time Life Books meant anything more than pop history and speculation on the paranormal. I’ll check the passage tomorrow and come back here.
ETA: I checked the book, and it says “free oxygen” to be exact; possibly it was ozone that was meant.