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Hydrochloric acid is more complicated than you think

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Re: Hydrochloric acid is more complicated than you think

#31

Post by mabbo »

ace2358 wrote: post #23
aj7 wrote: post #16

Many people have never seen stainless steel rust. I have. At a slightly leaky Swagelok compression fitting on the HCl-containing gas mixture bottle for a XeCl excimer laser. The leaking HCl combines with the room humidity to make an acid that will rust stainless. And it’s brown oxide rust, induced by the stripping of protective oxides by the HCl.

Remember, it’s stain LESS not stain FEEE. It merely stains less than regular steel. Not that it is unable to stain at all. Haha I remember when I first realised that.

Well, linguistically speaking, adding the suffix "-less" to a word implies "without", in English.

You can be penniless, having not one penny. You can be homeless- not just fewer homes but by golly none at all. You could be endlessly fearless and remain motionless when facing things that aren't harmless.

Doubtlessly, I've been tasteless in this reply.

Re: Hydrochloric acid is more complicated than you think

#32

Post by TillE »

fatnoah wrote: post #11
glasss wrote: post #3

I've never thought anything related to chemistry was simple, so if it really is more complex then I'm glad I'm in IT.

> I've never thought anything related to chemistry was simple I was an EE/CS major and getting A's in the two chemistry courses I took in college is one of my proudest achievements because I had to work so hard for them. Nothing about chemistry was intuitive or simple for me.

The first couple years of undergrad chemistry aren't too bad, it's stuff like advanced physical chemistry which finally beat my tiny brain into submission.

CS is much easier to grasp, the worst it really gets in undergrad is moderately difficult math.

Re: Hydrochloric acid is more complicated than you think

#33

Post by alwayslikethis »

dvh wrote: post #7
aabajian wrote: post #2

I remember a bit of this in undergrad gen chem. If pH stands for -log([H+]), how can pure water (H2O) have a pH of 7? In theory, there shouldn't be any hydrogen ions in pure water. Turns out there are two simplifications being made: i. H+ in aqueous solution is synonymous with hydronium ion (H3O+). ii. Water is in an equilibrium autoionization reaction with itself and the hydronium and hydroxide ions: 2H2O H3O+ + OH-…

Fun fact: The exact meaning of the letter p in "pH" is disputed, as Sørensen did not explain why he used it. Sørensen describes a way of measuring pH using potential differences, and it represents the negative power of 10 in the concentration of hydrogen ions. The letter p could stand for the French puissance, German Potenz, or Danish potens, meaning "power", or it could mean "potential". All the words for these star…

"negative decimal logarithm"

Re: Hydrochloric acid is more complicated than you think

#34

Post by mattigames »

mabbo wrote: post #31
ace2358 wrote: post #23

Earlier quoted context omitted.

Remember, it’s stain LESS not stain FEEE. It merely stains less than regular steel. Not that it is unable to stain at all. Haha I remember when I first realised that.

Well, linguistically speaking, adding the suffix "-less" to a word implies "without", in English. You can be penniless, having not one penny. You can be homeless- not just fewer homes but by golly none at all. You could be endlessly fearless and remain motionless when facing things that aren't harmless. Doubtlessly, I've been tasteless in this reply.

If English followed stricter rules "stainless" would mean "without stain", and to convey "unable to be stained" we would always use "unstainable" instead, a real but rarely used word.

Re: Hydrochloric acid is more complicated than you think

#35

Post by altgeek »

agumonkey wrote: post #28
kimmik wrote: post #8

Earlier quoted context omitted.

Low pH is needed for pepsin to work. Also to kill some pathogens. Doesn’t affect nutritional components of ingestion eg amino acids, vitamins and lipids.

makes me wonder what makes pathogen survive our stomach acid bath

https://en.wikipedia.org/wiki/Helicobacter_pylori

Re: Hydrochloric acid is more complicated than you think

#36

Post by bell-cot »

thaumasiotes wrote: post #29
bell-cot wrote: post #20

Earlier quoted context omitted.

> ...and how does it not destroy the nutritional value of the food? Acids destroying whatever they touch is mostly a "kiddie" version of reality. 99.9% of acids found outside of chemistry labs and industrial settings are no more dangerous or destructive ( as acids ) than soda pop, lime juice, or human vomit (all of which are acids). The reason is that some far stronger and/or more dangerous acids occasionally show up…

> 99.9% of acids found outside of chemistry labs and industrial settings are no more dangerous or destructive (as acids) than soda pop, lime juice, or human vomit (all of which are acids). > The reason is that some far stronger and/or more dangerous acids occasionally show up in household settings. Example: "battery acid", splashed on the skin, can cause horrific & life-long damage in seconds. I had to look up "batte…

> "The destructiveness of the solution is not determined by the acid [...] it is determined by the acid's concentration."

I'd say you're at the "know enough to be dangerous" phase. The destructiveness of concentrated H2SO4 (sulfuric acid) to flesh is at least as much due to its extremely exothermic hydrophilic behavior as to its low pH. Hydrofluoric acid is typically weak (pH-wise) as an acid, but is a horrific delayed-action contact poison. Concentrated nitric acid is a dangerously powerful oxidizer, or worse. Yet concentrated phosphoric acid is arguably less dangerous than propane.

[DISCLAIMER - Neither HN nor I are in any way responsible if you pop any statement in this item your empty little head, and head off in search of your very own Darwin Award. If you have no professional safety training in handling dangerous and/or highly-concentrated acids, then you should completely avoid them.]

Re: Hydrochloric acid is more complicated than you think

#37

Post by acchow »

aabajian wrote: post #2

I remember a bit of this in undergrad gen chem. If pH stands for -log([H+]), how can pure water (H2O) have a pH of 7? In theory, there shouldn't be any hydrogen ions in pure water. Turns out there are two simplifications being made: i. H+ in aqueous solution is synonymous with hydronium ion (H3O+). ii. Water is in an equilibrium autoionization reaction with itself and the hydronium and hydroxide ions: 2H2O H3O+ + OH-…

A key concept in biochemistry/chemistry is that almost all reactions are in some equilibrium between products and reactants, even H2O itself

Re: Hydrochloric acid is more complicated than you think

#38

Post by zdragnar »

ace2358 wrote: post #23
aj7 wrote: post #16

Many people have never seen stainless steel rust. I have. At a slightly leaky Swagelok compression fitting on the HCl-containing gas mixture bottle for a XeCl excimer laser. The leaking HCl combines with the room humidity to make an acid that will rust stainless. And it’s brown oxide rust, induced by the stripping of protective oxides by the HCl.

Remember, it’s stain LESS not stain FEEE. It merely stains less than regular steel. Not that it is unable to stain at all. Haha I remember when I first realised that.

Linguistically wrong, factually correct. There are many grades of stainless steel, and they will in fact develop rust over time.

430 is a mild stainless steel that has decent corrosion resistance, but you're not going to want to test it too hard.

304 is more common, albeit more expensive, and will hold up pretty well under most normal conditions.

Any expected prolonged exposure to salt requires 316 or better, though.

Re: Hydrochloric acid is more complicated than you think

#39

Post by naniwaduni »

bell-cot wrote: post #20
323 wrote: post #5

One thing I always wonder is what exactly does HCl dissolve in the stomach, and how does it not destroy the nutritional value of the food?

> ...and how does it not destroy the nutritional value of the food? Acids destroying whatever they touch is mostly a "kiddie" version of reality. 99.9% of acids found outside of chemistry labs and industrial settings are no more dangerous or destructive ( as acids ) than soda pop, lime juice, or human vomit (all of which are acids). The reason is that some far stronger and/or more dangerous acids occasionally show up…

It's always been funny to me that cartoon "acid" seems to be more characteristic of a strong oxidizing agent than an acid!

Re: Hydrochloric acid is more complicated than you think

#40

Post by kragen »

XMPPwocky wrote: post #15
basementcat wrote: post #9

Earlier quoted context omitted.

Water ice is a semiconductor and can be doped, like silicon, to make transistors. https://m.youtube.com/watch?v=o61wtb7dSRA

This video seems to confuse semiconductors with "materials with a negative thermal coefficient of resistivity". Saying "this gets more conductive as you heat it up" does not a semiconductor make, as far as I understand.

it's true that conventional insulators also have a negative tc but as i understand it that's because they're just really cold semiconductors
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