There is a very useful 2024 book by Dario Bressanini titled The
Science of Cleaning: Use the power of chemistry to clean smarter, easier, and
safer. A preview is at Google Books. He
discusses what works (a lot), what is useless, and what is dangerous. His
twelve chapters and their starting page numbers are:
1] Clean and Dirty, 6
2] Acids and Bases, 14
3] Limescale, 30
4] Soaps, 50
5] Detergents, 68
6] Chlorine-Based Bleach, 92
7] Oxygen-Based Bleach, 110
8] Laundry, 120
9] Dishes, 150
10] Disinfectants, 174
11] Baking Soda, 206
12] Household Surfaces, 224
One useless mixture is described in his detailed section on
pages 24 to 26 titled Baking Soda and Vinegar: a mixture that makes no sense. The
reaction is shown above. He says:
“Every time someone suggests mixing vinegar and baking soda
to remove a stain or unblock a drain, a chemist somewhere combusts. I couldn’t
say precisely when this particular craze began, but it’s definitely popular.
Pick any online cleaning forum or Facebook group, then look for a video on how
to unblock the sink, clean the carpet, or degrease a frying pan – or follow a
few influencers or pick through the hand hints section of a modern home
magazine – and it won’t be long before you begin to hear the inexorable chant
in your head ‘Vinegar and baking soda, vinegar and baking soda, mix them quickly
and watch the magic.’
It's a pity that not only does mixing them not work, it can
even be counterproductive. I know many of you are thinking, ‘But everyone is
saying it!’ Well, I’m afraid that everyone is wrong. No matter how many times
we repeat something false, it doesn’t become true. As I explained above, baking
soda is basic while vinegar is acidic. When mixed, they react instantly to
produce water, carbon dioxide, and sodium acetate, a mildly basic substance
with absolutely no cleaning properties. Likewise if you mix – in the correct
quantities – two highly corrosive substances like lye and hydrochloric acid. The
result is an innocuous water and sodium chloride mixture: salt water, in other
words. This happens because in chemical reactions, the properties of the
original substances disappear as the substances themselves no longer exist,
having chemically transformed. Therefore, it makes absolutely no sense to mix
substances that react with each other.
I realize, however, that it might be too flippant to dismiss
vinegar and baking soda in this way. As a chemist. I’ve often wondered how such
an inaccurate piece of advice could have become so popular. It wouldn’t be the
first time a wholly incorrect or ineffective home or traditional remedy has
propagated at such speed and with such fervor. Kitchen and cooking tips are an
excellent case in point, and some of the popular claims about how to clean or
keep our kitchens hygienic are so wildly inaccurate that they shouldn’t be
given the time of day. Why would throwing coffee grounds down the sink help
unclog it?
Anyway, the habit of
mixing vinegar and baking soda is so common, and its promoters are so convinced
of its effectiveness, that I decided to take a closer look. I spent a long time
thinking about it until I eventually identified three reasons this urban legend
has taken such a strong hold.
The first is psychological: When vinegar (or lemon juice)
touches baking soda, it instantly fizzes, producing a very impressive cloud of
foam and bubbles. It may look like something special is happening, but it’s
still just carbon dioxide with no detergent properties. It you put it in the
kitchen sink, the bubbles may drag up some of the dirt from the pipes and you
may interpret this as a cleaning miracle. I’m sorry to be the bearer of bad
news: It isn’t.
The second reason is the comforting knowledge that both
vinegar and baking soda are edible, so they must be completely harmless.
Everywhere we turn, we’re bombarded with warnings and ads fueling concerns for
our health and the environment, suggesting – incorrectly and often dishonestly –
that normal cleaning products, the ones ‘made of stuff with complicated names
we don’t understand,’ are hazardous for our health. Conversely, there’s no
denying that if you buy a product to unlock the kitchen sink, it will have a
warning symbol blazoned across the label. For example, as I said earlier, lye
should be used with caution, but it’s precisely its corrosiveness that enables
it to unclog your sink. So if you pick up a magazine or follow an influencer
and both tell you to use a much safer mix of vinegar and baking soda instead of
the more dangerous lye, the temptation to believe is difficult to resist,
especially if you’ve forgotten the chemistry you learned in school.
I’ve no doubt that many of you reading this will be ready to
swear that your mixture ‘worked’ – that the last time you used it, it really
did clean the thing you set out to clean.
This brings me to my third reason for this phenomenon, which
is strictly chemical. I said earlier that vinegar and baking soda (just like
lye and hydrochloric acid) cancel each other out, but only if you use the
correct quantities of the two reactants. I’ll save you the calculations, but a
liter of ordinary 6-percent vinegar requires exactly 84 grams of baking soda to
react fully and produce a solution of water, carbon dioxide, and sodium
acetate. Or, if you prefer, 100 ml of vinegar reacts fully with 8.4 grams of
baking soda. After the reaction, both the baking soda and the acetic acid
originally present in the vinegar no longer exist. I’m pretty certain none of
the concoctions touted as the remedy of all cleaning ills contain exactly these
quantities, which is the key to understanding why this mixture is believed to
work miracles. If you mix less than 8.4 grams of baking soda with 100 ml of
vinegar, the baking soda completely disappears when the two substances finish
reacting, and all that is left is the excess acetic acid that didn’t react.
Vice versa, if you add more baking soda, the acetic acid disappears and excess
baking soda is left. It is the addition of the leftover, unused reactants that
makes the mixture look like it is working.
There are generally two types of recipes for mixing vinegar
with baking soda: hose with an overabundance of vinegar, which create a watery
solution, and those with an overabundance of baking soda, where the latter is
barely wetted by the vinegar to form a paste. When the leftover reactant is
acetic acid, it is still active to a degree against any limescale crusting up
faucets, lining pipes, or stopping water from draining properly. This is why
the mixture seems to work, even if you’re only using what was left after the
reaction and not the full 100 ml you started out with. You’re wasting vinegar
and baking soda to create a liquid that is much less effective.
Some people even recommend making the mixture in advance and
keeping it in a bottle. I hope you’re beginning to see why this makes
absolutely no sense: As soon as baking soda and vinegar touch, at least one of
them ceases to exist. If any cleaning is being done, it is coming from the
leftover vinegar.
In the other recipes, the cleaning power comes from the
abrasive properties of the baking soda, which is useful for scrubbing a crusted
frying pan or removing buildup from an oven tray. Here, the amount of vinegar
recommended leaves a portion of the baking soda unreacted and lightly
moistened, so it can be used to scrape off the dirt. Once again, you’d be
better off not wasting vinegar at all and just dampening a small amount of
baking soda with water.”
Recent magazine articles also discuss why to not mix baking
soda and vinegar. One by Ashley Abramson and Barbara Bellesi Zito at Apartment
Therapy on July 31, 2024 is titled Why You Shouldn’t Mix Baking Soda and
Vinegar for Cleaning, According to a Chemist. Another by Caroline Mullen in the
New York Times – Wirecutter on September 15, 2025 is titled Please stop mixing
baking soda and vinegar to make cleaning paste.
Regarding what is dangerous there is a box all about bleach
on page 98 in white lettering on a dark
gray background with a heading of WARNING!:
"Never, ever, EVER mix bleach with another substance unless
you are 100 percent sure what will happen. You should especially avoid combining
bleach with acids.
Every year, hundreds of people end up in the hospital after
intentionally mixing acidic cleaning products with bleach. When bleach comes in
contact with an acid, it liberates poisonous chlorine gas, which was used as a
chemical weapon in WWI due to its toxicity. Unfortunately, there are a host of
toilet cleaners out there that are identical in everything but color, except
that some contain bleach and some contain hydrochloric acid. While cleaning the
house one busy morning, you could easily finish one bottle and start using
another without thinking – but the new bottle happens to contain a hydrochloric
acid-based cleaner, and before you know it, you’re choking on chlorine gas.
Separating bleach and acids also means avoiding using a
toilet that you’ve just poured a bleach-based product into. Urine is acidic, so
if it hits the bleach, don’t be surprised when you get a whiff of gas. And don’t
forget that vinegar and lemon juice are acids too. Ammonia and bleach are both
frequently used around the house. While they’re equally effective cleaners on
their own, when combined (which I beg you never to do), they can create a very
unwelcome – not to mention highly irritating and toxic – substance called
chloramine.
Bleach mixed with hydrogen peroxide (which is a weaker
oxygen-based bleach) produces an instant whoosh of oxygen bubbles. On its own,
oxygen is not toxic, but the fizz is so vigorous that it can easily send
splashes of liquid onto your skin and eyes. Please also steer clear of bleach
and ethyl alcohol mixtures, which can create a number of organic compounds –
from chloroform to acetaldehyde – in varying concentrations.
So I’ll say it again: Don’t mix bleach with any cleaning product,
really. Ever!”
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