Muriatic Acid - sealed, in a bag, in a steel drawer - looks like rust under the bag!?

[CharlesWaugh]

THE BACKGROUND:
In my shop I use a lateral file cabinet to keep my 'stuff in bottles and cans'
One drawer is adhesives (3M 77, hot melt sticks, Titebond, extra CA bottle tips, etc.)
One drawer is lubes (WD40, motor oil, grease, etc)
The third drawer is SOLVENTS (Acetone, lacquer thinner, MEK, naphtha, etc.)

I keep my 1 qt. plastic bottle of muriatic acid in that drawer, in a .006" thick polyethylene bag, with a twist-tie on the bag.
Not sure if it 14.5% or 29% (Mr. Lazy Pig Butt doesn't want to walk back out to shop to look)

THE EVIDENCE:
Under the poly bag there is 'rust', or at least it is orangish and slightly wet.
And, INSIDE the bag it is slightly wet and 'rusty'.

The paint on the drawer bottom right under the MA bottle is gone, and when I wiped the 'rust' off that area the paint is stripped and the steel is bare metal clean.

WHAT THE ****??

The plastic bottle is the original bottle, it's been opened a few times for use (like today, getting ugly mineral stains out of our toilet), then TIGHTLY capped - and kept in the poly bag, in the closed drawer, in the shop.

QUESTIONS:
What is going on here?
Why the rust? (OK... acid, I get it - but HOW?)
What is the 'wet'?

Is MA hydrophilic?
Can it propagate through a poly bag and original bottle (I assume it is polyethylene, PEEK, etc. layers)

Any chemists out there?

I'd ask my dad who was a research organic chemist, but he died 6 years ago, so that avenue is closed.

Any thoughts?

Thank you!

[bruce.desertrat]

Muriatic acid is volatile-ish (HCl is a gas, after all), and will certainly do the things you're describing, especially if it's in an un-cooled area in the summer. Under humid conditions you'll see the 'wet' you're talking about, because as a gas it is hydrophilic.

Why the 'rust' inside the bag is another question, but any kind of steel or iron that gets in there will cause that. It doesn't have to be more than a bit of steel wool or swarf.

in the (climate controlled) chem lab we would store it in glass bottles with tightly fitting caps with teflon liners, and we'd still end up with rusty acid cabinets.

Personally I'd be leery of keeping acids of any kind in a cabinet with solvents....way too much opportunity for , ahem, unintended reactions; were your dad alive, he'd probably regale you with all the exciting ways it could go wrong.

[CharlesWaugh]

Bruce,
Thanks, I'll keep it under my bed from now on.
:-)

Nah - I'll stick it out in my storage shed near the Nitric and Sulfuric acids.
True story - they're in glass screw-top acid bottles, in a styrofoam fitted container for shipping which is held closed by a bungee and labeled threateningly.

[jdurand]

Amazing things can get through plastic, some chemo drugs can go through Nitrile gloves in minutes. And, of course, Indian Meal Moths were found able to eat and digest polyethylene...at least enough to get through bags. I've seen that last one happen myself.

[pigpen60]

Your plastic bag is porous. Used to leak check machines and found a pile of things that leak that you wouldnt expect. We used helium to leak check.

[metric_taper]

The shelving at the home supply where muriatic acid is kept, look at the steel shelves, if the acid has been stored there, they are all rusty.
Metalworking forums talk about where a bottle left in a machine shop caused all the tables and ways to develop a rust film. I store mine outside, I place the original plastic bottle into a 5 gallon dry wall mud bucket, and snap the lid on tight.
Glass storage may help, but the threaded cap will not seal perfect, and you know a metal lid will soon be open air.

[NeiljohnUK]

The porosity of plastics is a major issue in my work with 'interesting' gases and liquids, the bottle is porous and the bag too, glass bottles are the only way to maintain purity and even then some acids will eat through them, HF especially. Some of our short delivery lines are PFA inside a purged with dry nitrogen PFA over jacket, just to keep the water out, as we aim for a dew point of -120°C or PPB, longer lines are 316L, often overjacketed for safety.

[jdurand]

Where I worked eons ago they switched to plastic coated glass after someone picked up two gallons of HCl at the same time and banged them together. The resulting spill cleared the building and resulted in a huge legal case... When the lady who caused the spill woke up in the hospital she found out a male (horrors!) worker carried her into the emergency shower and tore the acid soaked clothing off her. She accused him of attempted rape.

I think "thank you" would be more appropriate.

[DIYSwede]

-Isn't just chemistry sooo exciting?

Some recommended reading is John D Clark's "Ignition!", actually with a preface of Isaac Asimov (sic!)
Subtitle: "An Informal History of Liquid Rocket Propellants":

https://library.sciencemadness.org/l...s/ignition.pdf



Clips from p 89f (of 233) of this "unputdownable" biography, from the "days at the office" of pioneering US rocket scientists.



French Lab precautionary film: -What the stuff does to your PPE: clean, wet or dirty:

[bruce.desertrat]

There's a long series of posts by Derek Lowe on Sciencemag.com called "Things I won't work with", like this gem

https://blogs.sciencemag.org/pipelin...gen_difluoride

The heater was warmed to approximately 700C. The heater block glowed a dull red color, observable with room lights turned off. The ballast tank was filled to 300 torr with oxygen, and fluorine was added until the total pressure was 901 torr. . . (atmopheric pressue is 760 torr, for those of you not in the know, so this is a pressurized container at 700C filled with fluorine and oxygen

This is really exciting chemistry.

The whole list is here https://blogs.sciencemag.org/pipelin...wont-work-with

Mostly it's things that go BOOM if you look at them weirdly, but some of 'em will dissolve you first THEN go boom...

Every once In a while I read some of 'em just to remind myself just how much safer it is doing IT versus chemistry :-)