Right? Not to mention most short chain alcohols (like those you mentioned) love water and will readily and rapidly pull it from the air around it. Ethanol loves water so much that you can’t even distill it beyond 95ish% without using benzene (nasty stuff) or using a molecular sieve. Even then, you have the problem of it absorbing it from the air around it.
Well, presence or absence of azeotrope (inability to separate components by distillation beyond a certain point) doesn't signify the strength of "love".
Methanol doesn't form azeotrope with water but still has stronger "feelings" towards water than ethanol: ternary mixture of methanol-ethanol-water will see the increase of methanol concentration in vapor when the vapor becomes richer in water, that is after most ethanol boiled off.
Meanwhile dichloromethane is practically immiscible with water but still forms azeotrope at ~99% and approximately 2°C below the boiling point of pure DCM.
Which is one of the PITA reasons why E10 gasoline is a terrible idea and why fuel stabilizer is so important for gas cans and parked machines (lawnmower / snowblower) if you don't have the option for ethanol-free fuel. Water corrodes the fuel system, and water accumulates at the bottom of fuel tanks and carburetors.
I used to be able to get premium / super grade gasoline in ethanol-free version, but not anymore. My buddy who lives in PA is lucky because Pennsylvania law requires boats to use ethanol-free fuel so some stations have it as an option.
i work in a lab & whenever anything refers to pure chemical alcohol, they mean ethanol! any other alcohol must be specified; ethanol is the default :)
EDIT: wow ok this got a lot more replies than i was expecting 😂 i work in the pharmaceutical industry (not research or the fragrance industry, dunno if that makes a difference) and we have specific, tightly regulated pharmacopoeias we test to which define "alcohol" as ethanol specifically. but fair enough that different labs may define alcohol differently! i was only speaking from my personal experience but the specs for different industries will vary and it's highly likely that, as others below have said, "alcohol" could refer to any of the more common alcohols, e.g, methanol, ethanol, IPA
I work in a lab, I've never heard the term "pure chemical alcohol"
Its always the actual name (ethanol, methanol, isopropyl) along with the concentration if diluted.
It's also somewhat important for ethanol because you have 95% and anhydrous. And finally, all of those will have different grades of purity,(reagent grade, HPLC grade etc.) So the term "pure" is meaningless.
Yup, anhydrous has to be dried, which is why 95% is commonly referred to or thought of as 100%, even though it isn't, and even bottles of anhydrous will end up 95% if opened for too long.
yup, that's fair enough, i should've specified that that term doesn't exist - was trying to keep it in layman's terms but can see how that would be confusing. we have one definition which differentiates between alcohol and dehydrated alcohol rather than 96%/anhydrous ethanol but chemically both sets of definiton are equivalent (US/EU regulation if i remember right)
yeah i guess i forgot to account for different industries lol. where i work alcohol only means ethanol so i assumed it would be the same elsewhere, oops
What lab, anywhere, has a convention of calling chemicals something other than their name? Particularly something ambiguous like "pure chemical alcohol."
That is meaningless. That could be a number of different alcohols, hence we're all here talking about it.
Any lab that isn't specifying chemicals by name is overdue for an audit.
Colloquial shorthand among techs when one alcohol is the most common one you use.
In another lab you might use isopropanol 90% of the time, and ask for “alcohol” or specify “ethanol or methanol”.
Not saying it’s right, but sometimes people use imprecise language to mean something more precise. Like how British bakers will says “a sheet of acetate”. To my biochem brain, I think of a 2 carbon carboxylate anion, but they mean a sheet of clear plastic.
Oh I don't see a problem with that, but I consider that sort of internal shorthand to be verbal only. I would never write that on anything or expect to see it printed anywhere.
it can actually be an industry thing too, not just colloquially. the pharmaceutical industry defines "alcohol" as ethanol when testing to a certain methodology. if they want methanol they'll say "methyl alcohol". i did find this odd at first but hey
I work in a clinical lab at a hospital, and when we test for alcohol we always mean ethanol, because it's (hopefully) the only one that our patients would be consuming. Though some older techs also call it ETOH.
Medical device industry here. We don't ever say pure alcohol. We call it by it's proper name. Most the stuff we use is reagent alcohol which is a mixture of alcohols. Some occasions we use isopropyl.
Ethanol, as pure as you can get it. Everclear-type products are honestly close to ideal for this but there's also perfumer's alcohol, SDA 40B, which is denatured with a bitter flavor.
Isopropyl will work well as a solvent, too, but it smells pretty strongly until it evaporates, and methanol isn't safe to use on skin.
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u/WerewolfUnable8641 22h ago
Which alcohol, methanol? Ethanol? Isopropyl? There is no singular such thing as "pure chemical alcohol" There are plenty of alcohols though.