[cgladdin]

I feel a little stupid here, but can anyone tell me how to unstick a frosted glass stopper? I made a 5 M soln of NaCl and some of the solution dried in the joint - around the frosted-glass stopper of a 2 L volumetric flask, and now the frosted-glass stopper won't come out.

[malteser16]

try dipping it into hot or warm water. the neck of the flask should expand quicker then the stopper supposedly giving you time to pull it out. best idea I can think of at the mo.

[Dan]

1. Wet the stuck joint and leave it for a while. The salt should dissolve and loosen the joint. Keep the joint wet for the next steps.

2. If still stuck, tap the stopper carefully but firmly with something not too hard. A chunk of wood or a rubber mallet for example. In the old lab I worked in we had a piece of wood (called Kieth) specifically for this purpose.

3. If it's still stuck, heat the joint. Hot water, or failing that a heat gun (don't go crazy with it, just warm the joint).

4. You can completely submerge the bottle overnight in water and it will probably have popped out in the morning (you'll have to prepare a new solution though). You might need to attach a weight to it to do this.

Plastic or rubber stoppers are more practical for aqueous stock solutions of crystalline solids.

[fledarmus]

If your lab is old enough to have steam inlets, this is a good use for one. Gently soaking the top of the bottle in steam for a while should both dissolve the salts and warm up the outside of the bottle enough to pull the stopper.