I want to test reactions under vacuum.
I use for it an 1.2 liter glass 'weck' jar which can easily be evacuated and want to use KMnO4 + glycerin to trigger further reaction.
But because I have no access to the contents of the jar when it is closed for evacuation, I can not drop the glycerin on the KMnO4.
I tried the glycerin on a piece of paper and shaking after evacuation, but the wetted paper did not reach the KMnO4 pile.
Does someone have a 'trick' to mix these chemicals without having access to the content of the jar ?OldNubbins - 14-3-2018 at 13:36
magnets?mayko - 14-3-2018 at 14:49
Freeze the glycerine, then let it melt once the vacuum's pulled?VSEPR_VOID - 14-3-2018 at 15:06
Just let the glycerin in through the vacuum port without letting in any air. Be aware though, glycerin is extremely viscous and might take forever to
get through a long, small opening.
Technically you should de-gas the glycerin as well, if that matters for your rxn.Dr.Bob - 14-3-2018 at 17:35
If you just squirt the glycerine on the KMnO4, then close it up, it usually takes a minute or so to start, would that be long enough to evaluate the
jar? Or put the glycerine in a small upright beaker, vial or test tube, and tilt it to pour it. j_sum1 - 15-3-2018 at 04:22
Cody of Cody's Lab fame has been doing quite a bit recently using a vacuum chamber. I have seem him employ quite a few different methods for
manipylating objects in the container under vacuum.
Magnets is the obvious choice here. Suspend an object using a magnet or piece of iron on the inside and a magnet outside. Remove the outside magnet
and let it drop.
Electromagnet - then you can flick a switch.
Rig up something using a remote control. You'll need a power supply and receiver inside the vacuum though.
Go for something clockwork - a wind up toy or alarm clock or something.
Suspend on a thread and burn with a laser.
Variations can drop an object directly or drop a mass to manipulate something indirectly using levers or pulleys or simple linkages.DrP - 15-3-2018 at 04:40
Inject the reactants through a suba seal septa? Harristotle - 15-3-2018 at 04:52
See diagram.
Basically use glass bottle with septum made from icecream lid. Tilt to mix. Tape to side of vacuum jar.
Adjust material for compatibility with whatever you are studying.
Cheers,
H.Sulaiman - 15-3-2018 at 05:43
I can imagine so many uses for electrical connections to a vacuum chamber,
automotive spark plugs or 4mm binding posts with lots of epoxy ?Σldritch - 15-3-2018 at 06:47
Maybe i Harristotle already said this but i had a hard time understanding it...
Put something like a balloon under the your reaction pot and let Glycerine flow when it is tilted by the expanding balloon. That is of course if you
can not do it with magnets or lasers which seem much more convenient and reliable.DrP - 15-3-2018 at 06:53
Am I missing something? Why can't it simply be injected into the system through a seal? metalresearcher - 16-3-2018 at 11:55
I have a laser, but that only ignites KClO3 + sugar in air only and even then hardly, so too faint.
Quote:
Why can't it simply be injected into the system through a seal?
Well the 'seal' won't work very well when the jar is drawn vacuum.
I'll give the tilting metal a try.DrP - 17-3-2018 at 05:20
Well the 'seal' won't work very well when the jar is drawn vacuum.
I think I had the same problem once... I cut up and stuck together a few suba seals and made a double or triple septum. unionised - 17-3-2018 at 09:27
When the reaction starts and the bottom of the glass container gets suddenly very hot, it will shatter.
At that point you won't be working in a vacuum (you may be looking for the ER instead)metalresearcher - 17-3-2018 at 13:14
Here is my setup.
Photo 1: the complete setup, 2: the jar only, 3: another lid for the jar with electrical wires into the vacuum chamber for electric ignition, hose
barb and pressure gauge should be installed in other two holes. Might be easier than the KMnO4 + glycerin tilting option.
In photo 2 the reactants are put in a cell concrete vessel to prevent suddenly overheating the glass jar.
[Edited on 2018-3-17 by metalresearcher]NEMO-Chemistry - 17-3-2018 at 20:44
Do medicine capsules dissolve in glycerine? I have never tried, but those huge 500mg ones emptied then filled with glycerine. As it melts its way
through the capsule onto the KMnO4. Or dont fill it all the way, as you pull a vac would the capsule separate?
No idea if any of it would work, but you see my line of thinking? maybe you could come up with something along those lines.
Or make gelatin capsules and fill them, as you pull a vac they melt as the melting point drops. Might need to warm the chamber slightly
Or go hitech, arduino with bluetooth shield and a model servo, have a vial with the goo attached to the servo and pour it on via the blue tooth
commands......
[Edited on 18-3-2018 by NEMO-Chemistry]
[Edited on 18-3-2018 by NEMO-Chemistry]Magpie - 18-3-2018 at 19:48
I have not read this thread thoroughly so please for give me if someone has already posted this but some reactions can be triggered with UV light.metalresearcher - 23-3-2018 at 12:49
Finally I got it, but now with electric wires through a sealed hole in the lid.
I used KClO3 + sugar in a small vial and put a Kanthal wire coil on it and after evacuating the jar I chased a current of 8 amps through it. There was
almost no sound, unlike in open air when it gives a strong sizzling sound.
