Viewing a single comment thread. View all comments

Colourblindknight t1_it7ypuq wrote

Reply to comment by regular_modern_girl in Why does alcohol kill bacteria, but not the cells that our bodies are composed of? by Chairman_Mittens

This. Ethanol is very hygroscopic, meaning it’s really good at pulling moisture from its surroundings at higher concentrations. It will pull this water from whatever source it can find, including living tissue; that’s why it’s deadly to bacteria, it literally sucks them dry. I had a TA in university who told me a story of a guy who was banned from every lab on campus since he decided to take a slug of pure ethanol from the jug and had to be sent to the hospital for chemical burns in his mouth and throat. The main reason we can drink it is because it’s so diluted in most cases, and like you said we are made up of far more material than bacteria.

2

regular_modern_girl t1_it86e8a wrote

I don’t know if this is exactly true, but I’ve always heard that 100% ethanol basically doesn’t exist unless it’s stored under some extremely specific conditions, as literally any trace amount of humidity in the environment dilutes it (this is why I said 99% in the above comment, although again, I’m actually not totally certain this is the case, just what I’ve always heard).

Even everclear (which I think is like 75-80%?) will definitely mildly burn your mouth if you try to drink it neat. Personally, I find often even regular hard liquor kind of irritates my mouth and throat (part of why I don’t drink it), and I think this is why mouthwash tends to not actually have all that much alcohol overall (also of course because, even with all the additives to make it unpalatable, desperate people will still try to get drunk off of it).

2

Colourblindknight t1_it8h08r wrote

That’s because ethanol likes to form an azeotrope with water! When you’re distilling ethanol, there’s a point at about the 95% mark where the combination of hydrogen bonding between the OH groups in the water and ethanol as well as the vapour pressure of the solution make it so that the boiling ethanol will pull the water with it, making it basically impossible to distill 100% ethanol using regular non-chemical means. Because of the OH group wanting to interact with water, ethanol is super hygroscopic, meaning you are correct that if concentrated enough it will pull moisture from the air.

Pure ethanol absolutely exists though, and it’s a really useful solvent in a lot of labs. However, because of the reasons stated above, it’s generally kept in a sealed glass bottle over what’s known as molecular sieves. They’re these little beads of metal-silicates that basically form a microscopic mesh that can trap and “sieve” the water from the ethanol since the ethanol molecule is too big to get through.

2

jhwells t1_it8oe4b wrote

Everclear comes in multiple proofs/percentage abv:

  • 120, 60%
  • 151, 75.5%
  • 189, 94.5%
  • 190, 95%

In college I did a shot of 190 and within a few minutes the outer layer of tissue began peeling off the inside of my cheeks is disturbingly large sheets. It's not really meant to be taken straight and should be used as a mixer.

1