Sciencemadness Discussion Board

increasing the surface area of porcelain

Oscilllator - 24-11-2012 at 19:49

I have some smashed porcelain that I am using as boiling chips for boiling sulfuric acid, however there is a problem. No matter how many boiling chips I add, there is always significant bumping. I suspect this is a problem with surface area, a suspicion that was confirmed when I tried boiling the sulfuric acid with pumice. When boiling with pumice (which has a huge surface area, much higher than that of boiling chips) no bumping at all was observed.
However I cannot simply use pumice stones as boiling chips because as my sulfuric acid reaches a certain concentration (around 80-90%) the pumice starts disintegrating, and the sulfuric acid turns almost opaque with sediment.

The solution as I see it is to increase the surface area of the porcelain by etching it. This can be done with hydrofluoric acid, however a) I don't have any and b) I don't want to die.
Is there any other way to etch porcelain?

Vargouille - 25-11-2012 at 04:36

If you take a piece of coarse sandpaper to it, that might help to increase the surface area. Just be sure to wash it well afterwards.

hissingnoise - 25-11-2012 at 05:36

Quote:
No matter how many boiling chips I add, there is always significant bumping.

Odd? I've never needed chips when heating H2SO4!
That may be because I use a large, shallow casserole dish to concentrate the acid . . .

chemrox - 25-11-2012 at 15:27

Have broken porcelain chips like those worked with other liquids? I don't think the issue is surface area. You may already have too porous a medium. I think it's more likely a problem with porcelain quality. Some of it may actually be hard baked clay and it disintegrates on heating with strong acid. If you have a magnetic stirrer that may be the way to go or as hissingnoise says use an open dish. Did you obtain a barrel of battery acid?

Oscilllator - 26-11-2012 at 00:37

Quote: Originally posted by chemrox  
Have broken porcelain chips like those worked with other liquids? I don't think the issue is surface area. You may already have too porous a medium. I think it's more likely a problem with porcelain quality. Some of it may actually be hard baked clay and it disintegrates on heating with strong acid. If you have a magnetic stirrer that may be the way to go or as hissingnoise says use an open dish. Did you obtain a barrel of battery acid?


The broken porcelain chips significantly reduce the bumping, but do not eliminate it. I have not tried the chips on any other liquid apart from water, where the porcelain chips worked fine.
You seem to have misread my post as you imply that the porcelain disintegrates. It does not, the porcelain does.
I don't have a magnetic stirrer or an open dish, my only borosilicate vessel big enough is a 500ml erlenmeyer flask.
No I do not have a barrel of battery acid. I wish :(