RogueRose
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Cork withstanding hot HCl & ammonia gas
I have some flasks and condensers that aren't ground glass and I'm planning on using some 1/2" OD glass tubing to connect them and have some
stopper/bung to plug the flask and condenser. I'm wondering if cork will stand up to distilling HCl (both boiling lHCl/H2O and boiling ~20-34% HCl -
so the anhydrous gas). For the gas I'll bubble it into a 20% solution of HCl.
I'm doing the same with ammonia as well and I think cork should be fine as well as rubber.
I'm looking at getting some PTFE rod (12" long 25 or 30mm diameter) and turning stoppers down on a lathe, but I won't have that for a month or so, I
can get cork/rubber tomorrow.
Will the cork last a little while with HCl?
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Ubya
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i never trusted Corks so i always use rubber bungs, the few times i used them to just boil water in a test tube they started to crumble at the bottom,
so never used them again, but maybe mine were shitty quality. try a small scale experiment, and see if cork will withstand HCl or NH3 for the amount
of time you are going to use them
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happyfooddance
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You could probably increase the resistance of the cork to HCl by soaking it in vaseline or mineral oil, then wrapping it in teflon tape. The ammonia
shouldn't be a problem with cork or rubber.
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vmelkon
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I make silicone stoppers myself. I make the mold with crayola clay. It looks like they can't resists chlorine. Some kind of oily goo forms. They will
handle hydrochloric acid.
Signature ==== Is this my youtube page? https://www.youtube.com/watch?v=tA5PYtul5aU
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markx
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Most ordinary silicones nowadays are extremely diluted and do not withstand the effects of chlorine environment. In the good old days there were some
brands that could resist chlorine, but that was like 15 years ago. I remember that a certain brand of automotive red gasket silicone was such, but
that too became diluted and started to leach the dilutants....a gooey mess resulted.
When using machined PTFE stoppers be aware that the material has a strong tendency to creep and become really stuck in the conical flasks. It can be
impossible to remove after even a short while (a few weeks). If it is seated perfectly then anything short of smashing the lot with a hammer is not
going to work to remove the stopper. Having a layer of PTFE tape between the machined part and flask alleviates the problem somewhat.
Exact science is a figment of imagination.......
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S.C. Wack
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One should already have water glass and read the old lab manuals, because it's useful...corks might be the very first thing under the heading
Practical Hints. A solution of the OTC metasilicate may be acceptable here (but my silica gels say it's not identical).
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JJay
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I've used water glass-soaked corks with HCl before. It's not an incredibly satisfactory solution, but the corks did not degrade.
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RogueRose
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Awesome! Thanks for the hints on the silicate and the warning on the teflon!
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