Sciencemadness Discussion Board

Boiling Chips

99chemicals - 30-6-2012 at 17:08

I made some calcium sulfate boiling chips today by hydrating calcium sulfate with water and letting it hardening.

I am wondering if there are any chemicals that react with it under high temperatures. I made it for nitric acid production in the future.

If you want to see the video https://www.youtube.com/watch?v=h1TNyOmU0Os

Am I correct when saying that usually insoluble sulfates are pretty nonreactive.

vmelkon - 30-6-2012 at 18:50

Why do you need it for nitric acid production? Usually, people add conc H2SO4 to a nitrate and heat to drive off the nitric acid and no boiling chips are needed.

unionised - 1-7-2012 at 02:17

It's generally a good idea to add some sort of boiling chips to a distillation.
Calcium sulphate is generally fairly inert.
Unfortunately I think it dissolves in conc H2SO4 to form Ca(HSO4)2.

99chemicals - 1-7-2012 at 04:59

Would there be any problems using this in a nitric acid distillation? I am going to add Conc. sulfuric acid to KNO3 and distill the acid.

Would these be usable for making bromine.

Hexavalent - 1-7-2012 at 07:05

There may be a chance of;

2HNO3 + CaSO4 → Ca(NO3)2 + H2SO4

Very nice video and idea BTW - I'll be sure to make some soon.

[Edited on 1-7-2012 by Hexavalent]

99chemicals - 1-7-2012 at 07:28

Quote: Originally posted by Hexavalent  
There may be a chance of;

2HNO3 + CaSO4 → Ca(NO3)2 + H2SO4

Very nice video and idea BTW - I'll be sure to make some soon.

[Edited on 1-7-2012 by Hexavalent]


I don't think that Nitric acid is a strong enough acid to dissolve a soluble sulfate and make sulfuric acid. It may exist in equilibrium. From what I know Sulfuric acid is the strongest acid that is commonly encountered. It would take a stronger acid to make sulfuric acid or am I confused?


This is off topic but how do you get the arrow? Usually I use ->. Did you copy and paste or is there a code?

[Edited on 7-1-2012 by 99chemicals]

Hexavalent - 1-7-2012 at 07:50

Calcium sulfate is extremely insoluble in water, Wikipedia quotes 0.21g/100ml (anhydrous) and 0.24g/100ml (dihydrate) at 20°C .

BTW, there is a code for the arrow. User 'bfesser' referenced it in a thread in 'Forum Matters';

http://www.sciencemadness.org/talk/viewthread.php?tid=15528

It is really useful for showing reactions, symbols, superscript etc.


[Edited on 1-7-2012 by Hexavalent]

bbartlog - 1-7-2012 at 18:34

For nitric acid distillation, maybe these will be fine. But in general, I don't think calcium sulfate is a good material for boiling chips. The solubility is low, but hardly so low as to prevent some contamination of aqueous solutions. And further, CaSO4 will react with soluble carbonates or oxalates to produce the insoluble calcium carbonate/oxalate and corresponding other salt. I don't know where you got this idea but I would suggest sticking to more conventional boiling chips.

99chemicals - 2-7-2012 at 04:04

Quote: Originally posted by bbartlog  
For nitric acid distillation, maybe these will be fine. But in general, I don't think calcium sulfate is a good material for boiling chips. The solubility is low, but hardly so low as to prevent some contamination of aqueous solutions. And further, CaSO4 will react with soluble carbonates or oxalates to produce the insoluble calcium carbonate/oxalate and corresponding other salt. I don't know where you got this idea but I would suggest sticking to more conventional boiling chips.


I made aluminum oxide boiling chips by thermal decomp of aluminum hydroxide. Those work great but I wanted some that would be more resistant to atack by acid and base. You can dissolve the Al2O3 in ammonia, NaOH, HCl, H2SO4, HNO3 the list goes on.

Arthur Dent - 5-7-2012 at 04:00

I have to admit that the "boiling chips" I use are made of inert material... and are quite inexpensive to obtain.

At the dollar store, those little glass beads they use for arts and crafts and necklace-making, they come in various formats, but the 2/3mm beads are most useful.

But the "ghetto" version is to smash a piece of tempered glass... the "rock salt"-sized chunks of glass are perfect for such an application.

Robert

Mailinmypocket - 5-7-2012 at 04:05

Speaking of dollar store, I bought a cheap ugly dinner plate and smashed it to bits - The porous porcelain pieces with sharp edges work great!

liquidlightning - 5-7-2012 at 13:51

I generally use broken bits of glassware. Stirring rods tend to work the best. I just swirl them in some sandblasting sand for about a minute to get rid of the sharp edges.

dann2 - 8-7-2012 at 07:22


Pieces of pumice stones.

malcolmf - 9-7-2012 at 09:15

Hydroleca = Little pellets of porous, fired clay. Sold cheaply in UK garden centres, for greenhouse moisture trays, or just plain hydroponics.
For boiling chips, pick out a handful of the smallest pellets and use the rest in the greenhouse. (The easiest way I've ever seen for tomato growing!)
Pellets are available in 4mm, 6mm, 11mm, in sacks starting at 5l up to commercial greenhouse quantities.
Available in the rest of Europe, apparently , so probably available everywhere in some form.

achem500 - 3-8-2012 at 00:52

I often use pieces of chipped concrete. I tried porcelain once, (from an electrical insulator, actually) but it wasn't porous enough. Concrete chips worked well, but I'm not sure how inert they are. They worked for isopropanol distillation :D

platedish29 - 2-9-2012 at 22:14

Was just looking for this, Thanks!

Currently I make use of smashed dirty quartz stone, which works pretty well, specially in circunstances at which salt solutions boils annoyingly harsh.
The only problem is that it suffers some discoloration everytime it is heated up in solution. Should it be discarded? I'm not sure if it is porous enough??

[Edited on 3-9-2012 by platedish29]

vmelkon - 3-9-2012 at 14:29

I used pieces of granite. It works fine. It isn't very porous but I think having a lot of rough surfaces is good enough. I think it is quite inert to acids.