Sciencemadness Discussion Board

Rubber stopper and a weird story

Darkblade48 - 17-6-2005 at 18:20

Needless to say, I won't fill this post with long, meaningless drivel, but I'll get straight to the question :)

How in the world can you get a rubber stopper OUT of an erlenmeyer flask that has a smaller neck than the stopper? (And if you must know, someone [not me, honestly!] jammed a stopper into the mouth of the flask and then pushed it in)

It's just a normal, black rubber stopper, if it matters

Edit: The rubber stopper does NOT need to stay intact, but the flask does

[Edited on 18-6-2005 by Darkblade48]

Pyridinium - 17-6-2005 at 18:37

Prolonged exposure to low-boiling solvent naphthas will dissolve rubber.

Then there's always carbon disulfide, if you like to live dangerously.

Edit: Yes, actually toluene might work. Gasoline, even. It could take a while (few days?).

You might have to deal with a thick, nasty solution of rubber which has to be washed out a whole bunch of times with the solvent.

Is it natural rubber? I was assuming so.

[Edited on 18-6-2005 by Pyridinium]

Darkblade48 - 17-6-2005 at 18:40

Quote:
Originally posted by Pyridinium
Prolonged exposure to low-boiling solvent naphthas will dissolve rubber.

Then there's always carbon disulfide, if you like to live dangerously.


Might something like....toluene might do the trick?

[Edited on 18-6-2005 by Darkblade48]

neutrino - 17-6-2005 at 19:51

Add enough nitric acid to liquefy the rubber that’s getting in the way. I don’t know what concentration is best for this purpose, but I do know that the concentrated stuff works.

I’m not sure exactly what will be left behind from the rubber, but it shouldn’t be so hard to clean out.

zoomer - 17-6-2005 at 19:59

Can you drill a large hole in the middle of the stopper? If that doesn't relieve enough lateral pressure to squeeze it back thru, you could get a hacksaw or coping saw blade in and saw thru to the side(s) and remove it in pieces.

(I know, not nearly as much fun as carbon disulfide, but faster and cleaner :) )

Z

[Edited on 18-6-2005 by zoomer]

The_Davster - 17-6-2005 at 20:10

3 days in 70% nitric will render the stopper a black ooze. ;)

Darkblade48 - 17-6-2005 at 20:35

Quote:
Originally posted by rogue chemist
3 days in 70% nitric will render the stopper a black ooze. ;)


That was the first idea that did pop into my mind, but the problem is, it's quite difficult for me to get this stuff, and I don't have the proper glassware to distill it out from an xNO3 and H2SO4.

Natures Natrium - 17-6-2005 at 20:50

Hmm, direct prolonged contact with sulfuric acid renders stoppers hard as rocks. This might be more useful than it first looks, as the stopper would no longer be "springy" and putting pressure outwards.

Alternatively, drilling the hole and then sticking a bent piece of wire in and hooking the stopper is probably the easiest, safest bet. I recently found out that wood drill bits work extremely well at chewing through rubber...the secret being to only apply a light to medium pressure and let the bit do the work. This way the stopper doesnt slip around the bit as it does with regular drill bits, and you actually get a hole the same size as your wood drill bit.

Hopefully this helps. :)

12AX7 - 17-6-2005 at 21:14

Fire options...

(You knew I was going to mention it :D )

Heat steel rod to red heat, force through rubber and perforate.

Heat neck to soften, melt or burn rubber. (Pyrex is reasonably heat resistant, don't know annealing temperature offhand though.)

Etc.?

Never said they'd smell good :P

Tim

BromicAcid - 17-6-2005 at 21:25

A long time ago I tried to make ether by distilling a mixture of ethyl alcohol with concentrated H2SO4 and I used a rubber stopper in the erlemeyer that I distilled it from after prolonged heating the stopper melted ran down the sides and eventually failed catestrophically falling into the reaction mixture, don't know how this could practically be applied but it was interesting. Chloroform works to dissolve rubber as do other organics like is stated above, you don't have to dissolve the whole thing so it shouldn't be too much of a hassel to get it small enough to get it out.

Darkblade48 - 17-6-2005 at 21:38

Quote:
Originally posted by Natures Natrium
Alternatively, drilling the hole and then sticking a bent piece of wire in and hooking the stopper is probably the easiest, safest bet. I recently found out that wood drill bits work extremely well at chewing through rubber...the secret being to only apply a light to medium pressure and let the bit do the work.


I've been trying this, but my problem runs across the fact that the rubber stopper is stuck at the bottom of an erlenmeyer that measures ~20 cm high. It's quite difficult to find a screwdriver that long and still manage to apply enough pressure to drive the wood screw into the rubber stopper.

I did eventually manage it, but it was with a long screw, and not a wood screw, but it didn't seem to have any effect whatsoever on the stopper.
Quote:
Originally posted by BromicAcid...concentrated H2SO4 and I used a rubber stopper in the erlemeyer that I distilled it from after prolonged heating the stopper melted ran down the sides and eventually failed catestrophically falling into the reaction mixture


I'm assuming that hot H2SO4 does wonders at dissolving Rubber? I might have to do that outdoors one of these days....drilling with screws is getting really tedious

Silentnite - 18-6-2005 at 05:56

Quote:
Originally posted by Natures Natrium
Hmm, direct prolonged contact with sulfuric acid renders stoppers hard as rocks. This might be more useful than it first looks, as the stopper would no longer be "springy" and putting pressure outwards.


So it sounds as if the H2SO4 approach won't work. I know that dremels have snake attachements that you could perchance attach a sander to. It might take awhile, but it would certainly smell better then the chemical approaches and leave less mess.

Natures Natrium - 18-6-2005 at 07:33

Quote:
Originally posted by Darkblade48

I've been trying this, but my problem runs across the fact that the rubber stopper is stuck at the bottom of an erlenmeyer that measures ~20 cm high. It's quite difficult to find a screwdriver that long and still manage to apply enough pressure to drive the wood screw into the rubber stopper.

I did eventually manage it, but it was with a long screw, and not a wood screw, but it didn't seem to have any effect whatsoever on the stopper.


Well, note that I said "bits" not "screws". If you use an actual power drill and drill out a hole, you remove some of the inside of the stopper, giving it more room to flex...and allowing you to stick something through the hole to the other side and hook the underside of the rubber stopper and drag it out. Driving in a screw by hand would actually very marginally increase the size of the stopper, since you're wedging a piece of metal through it.

Actually, maybe I am in picturing this in my head wrong. Is the stopper stuck in the neck of the erylenmeyer, or is it clear down inside the body rattling around loose?

Mr. Wizard - 18-6-2005 at 08:20

Get an aluminum beverage can, cut a long strip of metal as wide as 1/2 the diameter of the cork. Straighten the metal strip to remove any bumps. Curve the strip to the inside radius of the flask mouth with a smaller bottle or a piece of wood. Make a U shaped tool. Insert the tool into the flask. position the cork into the inside of the U and lubricate the mouth of the flask. Pull it out. Wear leather gloves in case the mouth breaks.

Darkblade48 - 18-6-2005 at 11:31

Quote:
Originally posted by Natures Natrium

Actually, maybe I am in picturing this in my head wrong. Is the stopper stuck in the neck of the erylenmeyer, or is it clear down inside the body rattling around loose?


It's not stuck in the neck of the erlenmeyer, but it's inside the flask, rattling around.

The_Davster - 18-6-2005 at 16:40

You said you did not have the proper glass to make nitric right? But do you have sulfuric acid and a nitrate? I cannot see any reason why mixing the two in this flask would not work. Just mix the stoichiometric amounts of acid and nitrate together in your flask with the stopper inside, then secure a ziplock baggie over the flask mouth with a rubber band and allow the flask to sit until the stopper has dissolved.

unionised - 19-6-2005 at 04:23

Don't forget to calculate how big a bag you need for any CO2 and NOx that might be generated.
Better yet, do this outside (and I'm not sure I would bother with the bag).

sparkgap - 19-6-2005 at 04:27

A bag, or if you can spare the hassle, an alkali trap (use baking soda or something as cheap) for those noxious vapors.

sparky (~_~)

[Edited on 20-6-2005 by sparkgap]

Darkblade48 - 19-6-2005 at 09:11

Would I not need to heat the H2SO4 and the xNO3 in order to initiate the reaction?

garage chemist - 19-6-2005 at 09:20

Ozone turns rubber into dust at high enough concentrations (it attaches to the double bonds which are responsible for the elasticity). This is also the main reason for the embrittlement of old rubber parts.
If you happen to have an ozonisator, this would be the cleanest method.

H2SO4 + nitrate would also work, heating isn't required but greatly speeds up the process. Note that the black ooze might be difficult to remove from the flask.

[Edited on 19-6-2005 by garage chemist]

Geomancer - 19-6-2005 at 09:50

Invert the flask in a tank of water and manipulate it so that it contains a little bit of water and is stoppered from the inside. Ideally you'd want to lubricate the neck with glycerine or something, but this probably isn't needed. Remove the flask (still inverted with the stopper in place) and apply heat. Problem solved.

Obviously, you should take precautions against being sprayed with hot water/stoppers/glass in the heating step, though the stopper may well pop out well below the boiling point. Recall that rubber shrinks when heated, whereas glass expands.

Darkblade48 - 19-6-2005 at 16:49

As for the hot H2SO4 and the xNO3, I would end up destroying the stopper, but then how would I remove the black gunk?

As for an ozonator, I don't have one, so that's not an option (As of now).

If rubber shrinks when heated while the glass expands, wouldn't the rubber stopper tend to fall back into the flask?

My friend was suggesting I use a hacksaw blade and slowly cut it from the side, so that I can remove it in two pieces, I'll let you know how that goes :) It's been a very interesting "adventure" so far

[Edited on 20-6-2005 by Darkblade48]

neutrino - 19-6-2005 at 17:14

About that weird story... How did it get in there, anyway?

Darkblade48 - 19-6-2005 at 18:03

Someone thought it would be a "brilliant" idea to stick the stopper into the mouth of the flask and then push the stopper to see "if it wouldn't fall into the flask"

:o

Getting killed by an erlenmeyer in the cheapest way !

Lambda - 19-6-2005 at 19:46

Cut the head off a woodscrew, clamp a piece of tubing over the cutoff part (copper hydrolic brack lining tube is fine).

Clamp or glue them together.

Move your flask in a way that the stopper stands upright (in the pyramide position).

Warm the screw redhot, and then let it cool a little (test this on an other stopper).

Carefully push it into the rubber stopper (don't touch the glass wall with this hot screw).

Get your surgens-sculphal, that you use to disect mice, and other misfortunate small-crawlers.

Put some toiletpaper or sticky-tape around the rod, were it meets the flask (prevents scratching or breaking glass).

Start cutting the rims off the stopper, bit by bit after you have lubricated it with glycerine or detergent while rotating it clockwise (be carefull not to hit the surgens-sculphal against the bottom or neck of the flask).

Lubricate the stopper with glycerine or liquid detergent.

Put gloves on to protect your hands incase the flask breaks.

Let a string-loop slide inside the erlenmeyer, place the stopper over this loop and pull both string-ends together with the screw-shaft out (keep string-ends tight against the shaft while doing this).

If you have not by then slashed you wrists, you should have a happy day.
Quote:
He wanted an erlenmeyer as tombstone on his grave :D


[Edited on 20-6-2005 by Lambda]

Darkblade48 - 19-6-2005 at 22:42

After 3 long days of planning, hacking and pure frustration:

Me: 1, Rubber stopper: 0

I ended up finding this exacto knife (more like those surgical knives you'd use in biology, but with switchable blades) that had the blade i was looking for, one that was sharp at the bottom, like so (excuse my poor ASCII art :)),

|_|
|_|

The bottom portion was sharpened, so it was a matter of sticking the knife with the blade down onto the rubber stopper....mind you the handle was a tad too short, so I ended up sticking my fingers into the flask as well. After about 2 hours of just repeatedly hacking away at the stopper, it broke into two pieces, and I managed to pull it out :D

What a satisfying end to a nightmare

Edit: My poor "diagram"

[Edited on 20-6-2005 by Darkblade48]

[Edited on 20-6-2005 by Darkblade48]

Geomancer - 20-6-2005 at 17:00

Quote:
Originally posted by Darkblade48
If rubber shrinks when heated while the glass expands, wouldn't the rubber stopper tend to fall back into the flask?
[Edited on 20-6-2005 by Darkblade48]


No, you're heating the flask inverted, so gravity, as well as the increasing pressure in the flask, holds the stopper in place, like so (your ascii art inspired me):
Code:
_______ \\ / W: water S:stopper \\WWW/ \\S/ ||||||| H E A T


[Edit: fixed "art"]

[Edit: that's still not right. The preview works, but the main display shows the double backslashes literally, and doesn't work with single ones.
]

[Edited on 21-6-2005 by Geomancer]

[Edited on 21-6-2005 by Geomancer]