Vinegar increases killing power of bleach

[rowrrbazzle]

Vinegar increases killing power of bleach

Miner and his colleagues compared the ability of alkaline (pH 11) and acidified (pH 6) bleach dilutions to disinfect surfaces contaminated with dried bacterial spores, considered the most resistant to disinfectants of all microbes. The alkaline dilution was practically ineffective, killing all of the spores on only 2.5 percent of the surfaces after 20 minutes. During the same time period the acidified solution killed all of the spores on all of the surfaces.

Supported here: http://www.epa.gov/pesticides/factsheets/chemicals/bleachfactsheet.htm

   The application of bleach under crisis exemptions was limited to specific buildings or treatment sites...

Bleach and vinegar was were not combined together directly. Water was first be added to the bleach (e.g., two cups water to one cup of bleach), then vinegar (e.g., one cup), and then the remaining water (e.g., six cups).

Treated surfaces had to remain in contact with the bleach solution for 60 minutes. Repeated applications were necessary to keep the surfaces wet.

I’ve only had high school chem and bio, so FWIW this is counterintuitive to me. More acidic or basic, more germs die. Or so I thought, apparently incorrectly. And we’re concerned with spores here, not germs.

And these cites don’t mention poisonous gas from the combination, although other references do.

The first cite says the greater presence of hypochlorite (HOCl) is the reason it’s more effective. Why? And should I be using this solution regularly instead of diluted bleach?

Apparently the specific mixing directions reduce/eliminate the poisonous gas. How?

[ouryL]

Doesn’t vinegar or ammonia help liberate the chlorine in bleach? :eek:

[WarmNPrickly]

@ouryL

Doesn’t vinegar or ammonia help liberate the chlorine in bleach?

Yes, but notice the dilution and dilution method. The release of chlorine is probably pretty slow.

Bleach is a fine household dissinfectant as is and I see no reason to be encouraging people to be making unstable concoctions in their own home. If this solution is mixed in the wrong way or using the wrong concentrations the result could be a disaster. Acid and bleach is a big no no.

In the case of vinegar and bleach you are making sodium acetate and hypochlorous acid. Hypochlorous acid is unstable and spontaneously breaks down into chlorine gas in this way:

2HOCl -> HCl + HOCl[sub]2[/sub]

HOCl + HOCl[sub]2[/sub] -> HCl + HOCl[sub]3[/sub]

HOCl +HCl -> Cl[sub]2[/sub] + H[sub]2[/sub]O

HOCl[sub]2[/sub] and HOCl[sub]3[/sub] are strong oxidants (stronger than bleach) in and of themselves so I wouldn’t be suprised if that had something to do with the increased efficacy.

[PatriotX]

removed

[WarmNPrickly]

Seems I made an error last night. HOCl[sub]2[/sub] should be HO[sub]2[/sub]Cl and HOCl[sub]3[/sub] should be HO[sub]3[/sub]Cl. I knew what I meant.