You might be hearing people preach, PLEASE DON’T DRINK OR INJECT BLEACH! But what is bleach? I hope you’ll let me teach… When people refer to “bleach” they’re usually talking about chlorine bleach, which is a dilute solution of sodium hypochlorite (NaOCl) and it works as a strong oxidizing agent (oxidant). It attacks chemical bonds in bugs, dyes, and people! 

All molecules – everything from the NaOCl in the bleach to the proteins, lipids, and RNA in coronavirus particles – form by atoms (e.g. Na, O, Cl) sharing electrons. As an oxidant, bleach works by “stealing” electrons from other molecules, even if it has to break or otherwise damage those molecules’ bonds in the process. And bleach is really desperate for electrons…. This is great for messing up a virus or bacterium’s proteins and genetic info, and even dissolving their lipidy coats. But it doesn’t discriminate – it’ll mess you up big time too if you were to go injecting or drinking it! So don’t!

That’s the main PSA I have to say today…. But if you want to know the actual science going on, here are some more details…

Atoms in molecules are held to one another because they sharing pairs of electrons which are really tiny little negatively charged things that whizz around the central part of the atom, the nucleus, which is home to positively charged tiny but not quite as tiny things called protons and some other non-charged things called neutrons.

I like to think of atoms as dog walkers (the protons) trying to keep control over a bunch of dogs (electrons). Especially the super-hyper dogs that are out on the edge (valence electrons). Those hyper dogs are the most likely to get distracted – they can get attracted to nearby dogs getting walked by other owners and drag their walker and the rest of the dogs with it to form a new covalent bond (atoms held together by a shared pair of electrons) or, if they have enough strength, break off. How much strength they’ll need depends on how much their walker is pulling them back.

Their “pulling power” comes from the positive pull of protons and how well that pull can be felt by the electrons. Oxygen, for example, is a strong puller (it’s highly electronegative), whereas hydrogen is a poor puller. So when oxygen and hydrogen bond, the oxygen hogs their shared electrons, leading the oxygen to be partly negative and the hydrogens partly positive, this is why water’s “sticky.”

Atoms “come” with a certain number of protons that’s fixed for that element (e.g. oxygen (O) has 8 and always has 8 whereas hydrogen (H) has 1 and will alway have 1 or else it wouldn’t be hydrogen. But the # of electrons can change as atoms try to get their “ideal number” which usually corresponds to having a full “outer shell.” Electrons can get transferred from one molecule to another and we call this electron-moving reduction (gaining electrons) & oxidation (losing electrons). There can’t be one without the other, so we call the combo REDOX reactions.

A way to remember which gains & which loses is OIL RIG: Oxidation is Loss (of electrons) and Reduction is Gain (of electrons). It’s easiest to see when you have whole electrons coming and going like in batteries where electrodes flow from one side to another. But it also applies when it’s just the electron density shifting, like a dog deciding it likes its new co-owner better and switching loyalty. 

Oxidants are molecules that really want more electrons – and they’re willing to steal to get them, even if that means irreversibly damaging other molecules in the process. The more desperate they are (the stronger the oxidant), the more damage they can do – and the hypochloric acid in bleach is REALLY DESPERATE! So it is willing to mess up all sorts of molecules to get what it wants.  

Let’s look closer at what bleach is at the chemical level. Most household bleach is aka “chlorine bleach” which is a dilute solution of sodium hypochlorite (NaOCl). When it dissolves, it splits into Na⁺  & OCl⁻ (hypochlorite ion). 

NaOCl -> Na⁺  +  OCl⁻ (hypochlorite ion)

And that OCl⁻ can take a proton (H⁺) from water to give you hypochloric acid (HOCl), which is the major oxidant

OCl⁻ + H₂O ⇌ HOCl + OH⁻

Acidity of water (typically reported as pH) depends on the balance of free protons (H⁺) and hydroxide ions (OH⁻). Since we just stole a proton, we’ve made the solution less acidic (more alkaline, aka basic) and (since pH is an inverse log) raised the pH. But turns out we haven’t raised it quite enough. Because if the solution is just a little too acidic and/or if things heat up, bleach can break down in ways that give off toxic chlorine gas. 

For instance, 

HCl (hydrochloric acid) + HOCl ⇌ Cl₂ (gas) + H₂O

To prevent this (and other side reactions), bleach makers typically add sodium hydroxide to keep things from going sour. Speaking of which, don’t mix bleach with vinegar or other acidic things. Or really anything…

Chlorine gas isn’t the only side product to worry about. Bleach can react with ammonia (NH₃) to form toxic chemicals called chloroamines.

NH₃ + NaOCl -> NaOH + NH₂Cl

Ammonia a common ingredient in other cleaning products, so don’t mix cleaning products!

If you look at the above reaction, you see that the chlorine basically swapped places with one of ammonia’s hydrogens (it can actually do this a couple more times, to give you NCl₃). A similar swappage can happen in protein letters (amino acids) that have free amine groups (like lysine) and this can cause problems for those proteins. And it can oxidize the sulfhydryl (-SH) groups of cysteines and cause parts of a protein to form improper bonds to other parts of the protein. Cells work hard to keep a delicate redox balance, and bleach screws it all up, so metabolism goes haywire and all sorts of bad things. 

The basicity of the solution also does damage. People think a lot about acids as being really damaging, but bases are too! DON’T DO THIS – but if you were to touch bleach it might feel slippery – and that’s because it’s actually dissolving the lipids on your skin, turning them into soap in a process called saponification that happens when base meets lipid. And bases can burn you too!

Bleach can also mess with the lipids making up the membranes of all our cells – and of bacterial cells – and of the coating surrounding viruses. And HClO, being an uncharged, small, molecule can sneak in through membranes and cell walls to go to town. The basicity also contributes to the proteins unfolding (denaturing) – this exposes inner parts of the protein that like to stay hidden, away from water. Once exposed, these hydrophobic parts can stick to each other, causing proteins to clump up. 

But you know what also kills coronavirus? Good ole soap and water! Unlike some hardier germs, soap and water does the trick. So, while there are safe ways to use bleach – you have to dilute it first (5 tablespoons (1/3rd cup) bleach per gallon of water or 4 teaspoons bleach per quart of water) and ensure a contact time of at least 1 minute according to the CDC) – why not just go with soap? (but don’t inject or drink that either!) 

Note: Even if you’re not purposefully injecting or drinking bleach, if you don’t have adequate ventilation you can be inhaling toxic fumes. And Poison Control has seen a big uptick in accidental disinfectant poisonings. 

One last note – Wondering why bleach makes things look white? The reason things look certain colors is that the molecules in that thing absorb light of a particular wavelength (like removing a slice of a rainbow). Double bonds (often in rings) usually are responsible for absorbing light making dyes look colored. This is the case for the melanin giving your hair color. Oxidation can mess up these bonds, making it so that the dye can’t absorb that light like it used to, so the color disappears. 

more on topics mentioned (& others) #365DaysOfScience All (with topics listed) 👉

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