Chemistry

The manual for an ultrasonic cleaner says:

• “Cold, clean tap water is generally best suited as cleaning fluid. The cleaning effect can be enhanced by the addition of approximately 3 drops of washing-up liquid. Do not use caustic cleaners, ammonia, bleach or heavily perfumed detergents.” (emphasis mine)

I know a professional jeweler with decades experience who cleans jewelry (mostly gold) using “Mr. Clean”¹ and ammonia, diluted, in an ultrasonic tub. The cheap ultrasonic I bought for myself is not for pros - but jewelry cleaning is the advertised purpose and it has a stainless steel tub just like the pro models have.

So the question is, what’s the purpose of the ammonia avoidance guidance, and is the pro jeweler I know making a mistake by using ammonia?

UPDATE: I also have to question why the manual says to use cold water. Pro ultrasonics have built-in heating elements. The pro jeweler waits until the solution is hot before using it.

footnote:

① out of curiosity, is there a brand-neutral name for “Mr. Clean” (aka “Mr. Propre” in French regions)?

Found this on Mastodon. A "Christmas tree" of flasks with differently colored liquids.

What's your favorite so far?

cross-posted from: https://infosec.pub/post/5276026

I have a hot water dispenser, which heats the water to the temp you specify, on-the-fly. Sometimes this technology is called “insti-heat”. Instead of filling a kettle and waiting, it pumps water from a tank and heats it inline as fast as it draws it. Likely similar to how Nespresso machines work.

This means the limescale is hidden in the internal tubes. When descaling solution is put in the tank and the descaling program runs, there are no white chips of limescale like you would get in a water kettle. Yet it seems to be working because after descaling the water flows smoothly (as opposed to coughing and sputtering which is what happens when limescale is built up).

So it’s a mystery- where did the limescale go? Does it actually dissolve into the descaling solution? I ask because I’d rather not be wasteful.. I’d like to reuse the descaling solution, if that’s sensible.

I wish I’d grabbed a photo when I saw this but I thought it might be bad so I threw it away. Hindsight maybe that also wasn’t the best course of action but here’s my story.

Since there are a few ways to make flash cotton. I’ll give the basic ingredients I used but not the instructions. I used ammonia nitrate, sulphuric acid, and 100% cotton balls. I have nitric acid but it’s a pain in the ass to get, and expensive. So, I didn’t want to use it.

Anyway, I made this flash cotton like 3 years ago. I stuffed it all into a glass jar with a metal lid. I mean let’s face it. After you set a couple of pieces on fire, and show your 2 friends. What else can you do with it?

So, I stuffed it all into a glass jar with a metal lid, and forgot about it. Occasionally I’d see it in the kitchen drawer when I was looking for something and think yep there’s that flash cotton I made. I should burn it sometime.

Fast forward to the other day roughly 3 years from when I made it. I was looking for catfish skinning pliers when I found the jar. Only now that metal lid was half dissolved. The cotton was also gone. In its place was a yellow sludge that was growing little yellow crystals.

My initial thought was “hmmmmmmm that don’t look so good. Into the trash with you”. But now I’m curious what the hell happened? Also, maybe the trash wasn’t the best place for that?

I guess I’m just looking for insight.

Hello Chemists. I was wondering what the half-lives are for certain tear gas molecules used in tear gas used by the police. My house was tear gas due to an incident with a neighbor 5 days ago and now it still lingers.

They said that they used CN, OC and CS gas.

CN = (Orthochlorobenzalmalononitrile) OC = (Oleoresin Capsicum) CN = (Chloroacetophenone)

Thanks a lot for your help. Also, if you could note special properties of these molecules, about toxicity, etc, please let me know too :-)

Thank you!

cross-posted from: https://lemmy.sdf.org/post/3795687

"Many of these terms were in common use into the 20th century."

I hear many of these terms in common usage today, like potash, tartar, spirits, soda/soda ash, lime, soda lime, slacked lime, quicklime, lye, alkali, caustic soda, caustic potash, caustic alkali, quicksilver, chalk, cinnabar, fools gold, fulminating silver, fulminating gold, gypsum, vitriol has taken on a less specific meaning, aqua regia, turpentines, lead sugar, sulfur.

I think the reason that so many of these terms are retained is that the substances they refer to have been known for thousands of years in some cases.

brimstone is a much cooler name for sulfur that should be brought back. aqua vitae is a nice name for ethanol. the names of metals haven't changed.

cross-posted from: https://lemmy.sdf.org/post/3732588

A nice trip up and down the scale of things. I especially like the ones from 10^1 to 10^14, inhumane numbers attempting to be brought to a human scale.

Source: CRC Standard Mathematical Tables and Formulas (Zwillinger, Daniel) (Z-Library)