Chemistry question

[Dark Jaguar]

My friend recently told me an odd story about playing with an old chemistry set. Apparently this person (who unfortunatly doesn't remember the actual set or what specific chemicals it came with) got bored and poored everything into a single test tube. Apparently this dissolved the entire tube pretty quickly. It was stirred and the glass just sort of dissolved into the mixture and the mixture spilled out. What was really odd was this chemical, as my friend tells it, was completely safe to the touch without any pain or discomfort.

This sounded pretty odd to me so I submit it for review by anyone with knowledge of this. Can such a chemical actually come about, from a child's chemistry set, and if so what is it's composition and how can it be reproduced? I'm going window shopping later and... I mean I'm curious. Tall order to fill as far as info requests but I figure if there's a board I know of where someone would know, this one would be it.

 

[stup_id]

Can it be that is was actually a physical effect? maybe the mixture just heat the tube and the glass was already damaged, so it cracked...and when it spilled gave the apparience that is has disolved.

It is a wild guess... but since he actually got bored of the set, this migh imply it could be quite old

 

[Oleron]

Nope, unlikely. Chemistry sets, by design, contain only 'safe' chemicals. There is nothing in there that could dissolve glass. The only chemical I know of that can dissolve glass is hydrofluoric acid (although I'm sure there are a number of other more exotic options) and, believe me, they don't put that stuff in chemistry sets.

Could it be made from ingredients in a chemistry set? Commercially it is made from calcium fluoride and sulfuric acid, heated to 250 degrees C. I can't imagine your friend doing this for 2 reasons:

1. It is unlikely that the set contained sulfuric acid.
2. The fumes of the reaction would kill him quickly.

As for it not burning his hand, I have heard of hydrofluoric acid being absorbed by the skin before it gets a chance to burn it - the molecule is very small indeed.

 

[Maxwell's Demon]

^HF would indeed be absorbed through the skin before it could burn, but it would still do a lot of damage.

I had to go on a HF safety course a while ago as a lab colleague of mine was using it to etch optical fibres to make ultra sharp tips for a scanning near-field microscope. I remember them telling us that what was really nasty about HF was that you could knock a beaker of it onto yourself and not feel any ill effects for a while - however, the HF would absorb into your skin and start leaching the calcium out of the localised bone and turning it into jelly. Eventually it would destroy the ion balance that keeps your heart beating and kill you. This was illustrated by a case study of an Australian scientist who knocked a beaker of the stuff onto his lap - they had to amputate both legs as soon as possible and he still died.

All in all, very very nasty stuff and so I doubt very much if that was produced from a chemistry set. I'd go with the suggestion that the test tube was already cracked and the stuff flowed out. Or, it may have been a plastic tube - I guess if a sufficient quantity of acids/bases were added then the heat from the neutralisation might have been sufficient to melt the tube, but I find it hard to believe

 

[Dark Jaguar]

Indeed, and my friend may have just been making up a story at the time. Wouldn't put it past this one.

 

[Meffy]

I've seen cheap test tubes break cleanly and fnar -- a perfect split-off of the rounded bottom part, as if sliced with a super-knife. Sounds like what happened.

And I agree, no chem set maker would've provided materials that could do that. The first sets I owned, made in the 1950s, included plenty of poisonous chemicals. F'rex, copper sulfate is pretty nasty stuff, and it's a bright blue that looks altogether too candy-like to be given to kits as young as I was... but I knew what NOT to do.

 

[ponderingturtle]

I've seen cheap test tubes break cleanly and fnar -- a perfect split-off of the rounded bottom part, as if sliced with a super-knife. Sounds like what happened.

And I agree, no chem set maker would've provided materials that could do that. The first sets I owned, made in the 1950s, included plenty of poisonous chemicals. F'rex, copper sulfate is pretty nasty stuff, and it's a bright blue that looks altogether too candy-like to be given to kits as young as I was... but I knew what NOT to do.

Sets in the 80's still contained it, I remember heating it to drive out the water turning it white.

 

[Meffy]

If you mix solutions of copper sulfate (blue) and sodium ferrocyanate (pale yellow, aka yellow prussiate of soda) together, a clumpy precipitate the color of dried blood will form. One chemistry set I had called this a "Science magic trick -- Turning 'water' into 'wine.'" =@.o= I hope whoever wrote that got fired PDQ.