why glass stopper is stuck in the reagent bottle containing sodium hydroxide?

Question

i want a short answer for this also do mention that y not stoppers of other materials like wood metal etc...

Answer 1

It's actually the OH groups from the Hydroxide.

These groups atack the surface of the glass at the stopper interface causing a thing silica gel layer to form. This silica gel hardens and forms a surface similar to sandpaper. All these tiny pieces of high silica glass act as a high friction surface preventing the stopper from being pulled out.

A similar process occurs with metal lids on glass jars. If left closed for a long time the lid gets stuck on the glass and if you are finally able to open the jar you'll hear a sound like sand grading between the lid and the jar. These are the tiny pieces of silica formed from the silica gel layer.

It has nothing to do with Sodium Hydroxide bonding to the glass. If that were true the entire contents of the bottle would be stuck to the side walls... and I'm guessing it isn't.

Answer 2

Sodium hydroxide is related to the ingredients in glass, one of which can be soda ash and thus causes chemical reactions on the surface that cause the close fitting stoppers to bond in place.