Sciencemadness Discussion Board

White residue from reaction of sodium hydroxide and silica gel

Draeger - 26-5-2020 at 06:25

I've gotten around to do some glassware cleaning and am trying to get rid of the residue named above. The container which it is in smells lightly stinging and reminds me of rock and earth in odor, somewhat, if that helps. I tried to let it stand under some HCl overnight to see if it would dissolve in it, but nothing has changed. The residue still sits at the bottom and nothing has dissolved.

Do you have any advice on how I could clean it?

dawt - 26-5-2020 at 08:56

Sounds like you got yourself some sodium silicates. If they don't dissolve in water I don't think there's much you can do chemically to remove them that wouldn't also damage the container (assuming it's glass). If it's plastic you could try some HF (easily made by mixing a fluoride salt with an acid, but beware of the fumes and take precautions against getting any on your skin). Otherwise scrub as best you can, ignore the residue as it'll likely be inert to whatever you're going to store in that container in the future, or simply trash the container.

Draeger - 26-5-2020 at 09:13

Quote: Originally posted by dawt  
Sounds like you got yourself some sodium silicates. If they don't dissolve in water I don't think there's much you can do chemically to remove them that wouldn't also damage the container (assuming it's glass). If it's plastic you could try some HF (easily made by mixing a fluoride salt with an acid, but beware of the fumes and take precautions against getting any on your skin). Otherwise scrub as best you can, ignore the residue as it'll likely be inert to whatever you're going to store in that container in the future, or simply trash the container.

Definitely not going to try anything with the element fluorine in it. Scrubbing it is then. Thank you.