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Boiling Stones?

subsecret - 16-8-2013 at 12:40

Pretty short question:

What things are best for use as boiling stones?

Mailinmypocket - 16-8-2013 at 12:46

Buy a cheap white porcelain mug or plate at a dollar store, smash it to hell in a clean way to avoid contaminating it with dust etc. Broken lab glass works well also. Boiling stones are best but they are not always cheap.

Endimion17 - 16-8-2013 at 15:49

If you choose porcelain, remember that you can only use it once, or only for one purpose, as it has pores.

It's best to have a box for broken glass tubes. I never throw anything except it's completely useless. Broken laboratory glassware can be quite useful.

smaerd - 16-8-2013 at 16:16

Or buy a jar of boiling stones for 10 dollars that will last probably a life-time.

Pyro - 16-8-2013 at 17:16

also activated charcoal or sand will work!

violet sin - 16-8-2013 at 18:36

kinda helpful but not fully on track here. depending on what you are boiling down some things can be used as nucleation sites for bubbles to stop bumping. while concentrating a CuSO4 solution from sulfuric acid w/ copper electrodes. I used copper wire ~10" long. at one end I wrapped some fine wire in a bunch and held in place by a medium gauge wire, all copper. basically it looked like a funky broom. but it was quick to make, cheap, durable and easily replaceable. although the bumping didn't stop completely, it enabled me to concentrate back to strong H2SO4 and crystallize much of the copper sulfate w/o any glass breaking.

this idea doesn't work for hotplates w/ mag stirrers. just a make-shift fix for a problem I had while messing around and getting back into chem. like working with mason jar type chemistry off youtube.

confused - 17-8-2013 at 10:10

i have at one point used calcium sulfate chips as boiling stones...it all depends on what you're reacting.
if youre using broken glassware, i reccomend sanding it first to scratch it up, increasing the nucleation sites for bubbles to from. (being careful not to cut yourself while doing so)

Fantasma4500 - 17-8-2013 at 10:47

charcoal??
my logic tells me you would need something with VERY VERY low density for that to work (:
not sure if liquid helium would be low enough??

to my ''luck'' my 250 mL flask just decided to start cracking in the bottom, no HNO3 or acetone destillation.. luckily it has some thick glass parts which will surely work well for boiling chips which is also often a problem
smarter every day (:

Pyro - 17-8-2013 at 11:34

well, activated charcoal, the granules sold for fish tank filters

Oscilllator - 17-8-2013 at 14:58

I use coke (the roasted coal kind) for my boiling chips, after having numerous bad experiences with broken glass as boiling chips. It is extremely porous carbon, and as such is pretty much immune against everything. The only problem is small bits of the coke break off, and the boiling chips have a tendency to float round in the substance you are boiling.
Other than that, they cost 60c/kg and have a high enough surface area that I have never had any problems with bumping while using them. Highly recommended!

The_Davster - 17-8-2013 at 15:23

broken clay flowerpots

Cave_Johnson - 17-8-2013 at 16:32

Usually I use silica gel beads. They provide pretty good anti-bumping insurance (maybe not as good as broken glass) without being sharp or prone to disintegration, and they're big enough to be easily removable from a distillation mixture or whatever. I reuse them since they're not extremely porous. Probably the worst part is getting packs large enough to be useful, unless buying them is an option, in which case it might be better just to buy real boiling chips in the first place.

testimento - 18-8-2013 at 01:17

I have used common silica sand (beach sand) that is purified prior adding. Sand consists primarily of silicon dioxide, same stuff as glass, so there will be no compatibility issues with all chemicals that can go with glass. I have used it for ether synthesis, purifying acetone, toluene, DMSO and several other reactions. Few spoonfuls are quite enough for 5L flasks to create nice steady curtain of bubbles, so the ease of getting a few buckets of it I just throw away the residue sand after use.

subsecret - 18-8-2013 at 06:20

I've heard not to use sand as it can scratch the glass. It would really be a pain if you got it wedged into a ground glass joint without noticing.

Blue Matter - 18-8-2013 at 08:32

This thread is so over complicated either use broken boro silicate glass if you have it or buy actual boiling chips there like 5-15 dollars.

sonogashira - 18-8-2013 at 10:34

Pumice. Glass is useless for heavily-bumping solvents.

subsecret - 25-8-2013 at 14:16

I made some boiling stones from plaster of Paris. I'm not sure how inert is is, probably not very inert. These stones will slowly absorb water from solutions, so begin boiling soon after adding them to a solution.

subsecret - 27-8-2013 at 13:46

UPDATE:

These boiling stones are reactive to hydrochloric acid and some of its salts.

Is there a place to find a reactivity series for inorganic polyatomic ions?

[Edited on 28-8-2013 by Awesomeness]

Hexavalent - 27-8-2013 at 13:50

Quote: Originally posted by Cave_Johnson

Probably the worst part is getting packs large enough to be useful, unless buying them is an option, in which case it might be better just to buy real boiling chips in the first place.

What about the silica-gel based cat litters?

confused - 27-8-2013 at 19:46

you can also buy silica gel in photography stores, they use it as a desiccant

subsecret - 28-8-2013 at 12:03

Will silica scratch borosilicate glass? I've heard that sand will...

IrC - 28-8-2013 at 13:17

Quote: Originally posted by Awesomeness

Will silica scratch borosilicate glass? I've heard that sand will...

Too many questions easily answered you keep asking, not just in this thread. Do you ever actually bother to search before asking others?

From Google search terms : hardness silica, hardness borosilicate glass

http://www.reade.com/Particle_Briefings/mohs_hardness_abrasi...

http://www.tedpella.com/company_html/hardness.htm

http://www.roymech.co.uk/Useful_Tables/Matter/Glass.html

http://www.skylinecomponents.com/Borosilicate

I should add you can think I'm being rude no matter to me. We all have jobs, lives, hobbies. Meaning little time to work for free for others who do not wish to work for themselves. Most of us search long and hard before bothering to ask others. There is an etiquette here which has existed many years. Most try hard to not appear as if we would rather get someone else to work for us rather than do it ourselves. I can see maybe your asking an innocent question yet when recurring patterns become clear across multiple threads it simply gets annoying. A true scientist spends long hours in study. So it makes having to also study for others very unappealing.

[Edited on 8-28-2013 by IrC]

bfesser - 28-8-2013 at 19:04

Quote: Originally posted by IrC

Too many questions easily answered you keep asking, not just in this thread. Do you ever actually bother to search before asking others?

I second this. Frustratingly, such behavior is not unique to this thread/user.

Also, just invest in some goddamned PTFE boiling chips, people! I bought a full jar (one pound, if I recall correctly) from eBay for less than 20 USD (again, IIRC), and have yet to make a dent in it after years of use. They're not perfect for everything, but they're damned close.

Varmint - 29-8-2013 at 04:39

The ultimate boiling chip for most purposes is ceramic tumbling media.

Rinse them off, blow with compressed air if you have it, or just do a boil for the fun of it to clean them up.

Obviously if your liquor eats ceramic, these become non-ideal, for everything else, the number of nucleation sites is phenominal, super-heating ENDS with these as boiling chips.

Also, if not inherently obvious, these are porous, so you want to keep individual chips doing similar work. That is to say pay attention, you don't want to drop chips from a previous caustic boil into an acid boil without contemplating the possible side effects.

5lb bottle = $14.99 + Tax (US)

http://www.harborfreight.com/5-lbs-medium-ceramic-abrasive-p...

DAS

bfesser - 29-8-2013 at 06:39

<a href="http://www.amazon.com/Chemware-D1069103-Boiling-Stones-Grams/dp/B002TG3W1M/ref=sr_1_1" target="_blank">Chemware D1069103 PTFE Boiling Stones, 450 Grams</a> <img src="../scipics/_ext.png" />

Re-using boiling chips is an all around bad idea.

Varmint - 29-8-2013 at 07:25

Which is why I mentioned it.

DAS

subsecret - 30-8-2013 at 12:02

Sorry, IrC. Thanks for the reminder.

On another note, I purchased a pumice scouring block at Lowe's. It's much more difficult to crush this block into small pieces, as it hitting or crushing it simply crushes the air pockets. Boiling stones made from this material (as previously identified) work well.

Magpie - 30-8-2013 at 12:38

I also use little pieces of a broken clay pot.

I'm interested in the silicon carbide boiling stones commercially available. It's not that I need them for boiling stones: I need porous silicon carbide for use as a catalyst support.

Are the silicon carbide boiling stones porous? Or do they just rely on sharp edges for use as boiling stones?

testimento - 15-2-2014 at 20:14

What boiling stone material would be ideal for concentrating sulfuric acid? I tried borosilicate glass shards, silica sand and curshed porcelain fuse shells, but it just kept bumping. Havent tried silica gel yet.

BromicAcid - 16-2-2014 at 07:08

Because concentrated sulfuric acid is so dense and thick boiling stones do not do the trick. Old school capillary N2 action would likely be the best.

Oscilllator - 16-2-2014 at 19:26

Quote: Originally posted by testimento

What boiling stone material would be ideal for concentrating sulfuric acid? I tried borosilicate glass shards, silica sand and curshed porcelain fuse shells, but it just kept bumping. Havent tried silica gel yet.

I have used coke (as mentioned previously on this thread) to prevent the bumping of sulfuric acid. In my case it completely eliminated the bumping

ZIGZIGLAR - 16-2-2014 at 20:38

Can't you reuse ptfe boiling chips? I use these as they offer the flexibility of working well under vacuum, as I don't have a nitrogen or argon line ...

I've used capillary bleed tubes with success too. You can easily make them yourself by just buying 6mm OD borosilicate tube and holding the tip with needle tip plyers, heating the end up really hot, then stretching it out until you have a thin tip, then just break/cut the end bit off. The 6mm OD will slide comfortably through any gland designed for thermometers. If oxidation is a concern, then you're probably using a nitrogen bleed already, I imagine.

Refinery - 17-2-2014 at 07:34

Quote: Originally posted by Oscilllator

I have used coke (as mentioned previously on this thread) to prevent the bumping of sulfuric acid. In my case it completely eliminated the bumping

Can you say, is graphite essentially a pure carbon and would it be suitable for the purpose? I have a similar problem and only place I can get coke is from industrial supply and they sell it only in 40kg bags.

And don't you get fine particles into the sulfuric acid, turning it like black goo? What do you use to filter the carbon off?

[Edited on 17-2-2014 by Refinery]

organicchemist25 - 17-2-2014 at 10:59

When I first started using boiling chips I used broken up pieces of a spark plug. They worked fine. I eventually just bought two big containers of boiling chips. They are relatively inexpensive.

Oscilllator - 17-2-2014 at 15:42

Quote: Originally posted by Refinery

Quote: Originally posted by Oscilllator

I have used coke (as mentioned previously on this thread) to prevent the bumping of sulfuric acid. In my case it completely eliminated the bumping

And don't you get fine particles into the sulfuric acid, turning it like black goo? What do you use to filter the carbon off?

[Edited on 17-2-2014 by Refinery]

The main property of the coke that makes it a good material for boiling chips is its extremely high porosity. Graphite is not porous, so i dont know if graphite would be suitable for boiling chips but its worth a try. Coke is quite hard so it does not disintegrate into a black goo and because I used chunks with a diameter of 5+mm, I can just decant the sulfuric acid off the coke.
Even though it comes in 40kg sacks, its probably worth getting one (or more!) to power a forge like the one I have. I have been able to do many high temperature experiments with my forge (like casting copper) so it's well worth the money.

packetforger - 21-2-2014 at 05:40

We mainly use small pieces of pumice in the lab, however smashed up flowerpots is a viable alternative according to the manual that came with a chemistry set I bought as a child.

Pieces of plates/pottery are good too, but I suspect the reason we use pumice in the college is due to the fact it is very porous, giving rise to many nucleation sites for bubble formation to prevent the forming of hotspots and the like (instead, you get many small bubbles).

Pumice is widely available as it is used for scraping dead skin off, just buy a lump of it and hit it with a hammer to make the small pieces. Perhaps washing it may be a good idea as it might be contaminated with some antiseptic or something (I doubt it, but better safe than sorry...)

[Edited on 21-2-2014 by packetforger]

bfesser - 21-2-2014 at 06:16

Pumice and most ceramics will scratch the hell out of your glassware. Better to stick with boiling sticks or proper boiling stones.

ZIGZIGLAR - 21-2-2014 at 15:17

Why doesn't anyone use capillary bleed tubes these days? They add the flexibility of being viable during vacuum distillation and can also be used to introduce N2 for sensitive reactions or boiling of highly flammable solvents ...

Oxirane - 11-10-2014 at 14:09

Have you any experience on silica gel except for the one poster on the first page? I found two types of gel, the clear one for smaller pores and larger, opaque ones as cat litter. Tried to vac distill pure some DMSO, but it started to bump so badly the whole distillation setup was gonna jump off the table and I was afraid it could strike so hard to implode the vacuum so I immediately cut it off.

S.C. Wack - 11-10-2014 at 15:45

A problem with silica gel is that it's only so inert, but it's unsurprising that your boiling stones failed in vacuum distillation of DMSO.

I'm also a fan of the off-topic use of pulled capillaries through the thermometer hole for vacuum distillation, and have heard that a proper capillary pulls negligible air through it, but haven't tested this with even a balloon. A fine capillary end on a stout tube can usually withstand an amazing bumping ordeal.

[Edited on 11-10-2014 by S.C. Wack]

Dr.Bob - 11-10-2014 at 19:15

Pumice is likely softer than most boiling stones. I have a bottle of them, and I think they are made of alumina, which is quite hard and will scratch most things well. They specifically state that they are high porosity, I think that is key, magpie, so the SiC ones are likely the same highly porous material.

If anyone wants a small amount, I am happy to provide a little for free. Magpie, if you think Al2O3 might work, let me know and I will send you some to test.

Amos - 11-10-2014 at 20:25

I chiefly use pieces of quartz salvaged from geodes; they're free and easy to obtain and they get the job done really well.

Little_Ghost_again - 12-10-2014 at 02:05

I use the broken ceramic tubes from the tri pod triangles, a very small bit does the job perfect!

Refinery - 10-7-2020 at 12:56

I'm pretty much betting between these three options:

1) Bleeder tube (with forced air if system is open)
2) Activated carbon granules
3) Calcium sulfate chips (prepared as gypsum, spread onto plastic/glass/al foil, chipped when dried for 24h)

Mateo_swe - 11-7-2020 at 03:07

I been looking for some reusable boiling chips and it seems they are not cheap nowadays.
500g of PTFE boiling chips would cost me almost 90 Euros on ebay.

So what is usable instead of the PTFE boiling chips?
I read broken glass pieces, small ceramic pieces or a crushed clay pots for flowers would work.
Some said crushed dinner plates works but can only be used once, it that true?
I guess i can crush some old dinner plates or flower pots and put in a jar to use when needed and if they only can be used once its ok as they cost almost nothing.
Are any of the cheap alternatives better than the others?

[Edited on 2020-7-11 by Mateo_swe]

pneumatician - 1-9-2020 at 14:37

glass balls? I use it and work 100% easy to clean, well, sometimes hard to clean but if too hard I send to Hell

very cheap for 1kg, a lot of balls!!!

used in rectification columns!

https://duckduckgo.com/?q=Solid+Soda+Glass+Balls+columns+lab...

[Edited on 1-9-2020 by pneumatician]

teodor - 2-9-2020 at 02:27

Once I took a thick ceramic plate, smashed it with a hammer, selected pieces of proper size. They where glazed but after few boiling of acids they become completely unglazed as well as free from metal contaminations. They serve me well. I didn't get good results with glass balls - they just don't prevent bamping (in most cases). Unglazed porcelain has pores which are essential for smooth boiling.

[Edited on 2-9-2020 by teodor]

[Edited on 2-9-2020 by teodor]

unionised - 2-9-2020 at 04:03

I'm fairly sure that the reason people took to using capillary leaks for vacuum distillations i that boiling chips simply don't work properly.

For solvent recovery from non aggressive solutions I use a matchstick with a bit of wire wrapped round it so it sinks.
For acids I use silica gel.

I found that broken glass, while generally available in chem. labs, isn't very effective.

pneumatician - 2-9-2020 at 08:59

maybe you not use enought balls or too big. Sometimes I get a bloob but so neutralized... it's interesting to see

glazed ceramic is with lead so if you remove it is in your solvent.

teodor - 2-9-2020 at 10:03

I've made some illustration what I mean by "glazed ceramic".
I was mistaken, the glaze is still there. But after smashing there are chips which contain it only on very small surface that it is almost unnoticeable, probably I just selected most unglazed over the time. These on picture where already used 5-15 times. I don't see any signs on wearing.
The glass balls I compare them to is of 1.5-3 mm in diameter.

Fyndium - 2-9-2020 at 11:04

I indeed posted about this on another topic, but for the record, activated carbon granules have worked for me for everything I've used them so far, from acetone, ethanol, styrene to sulfuric acid. I used them also in vacuum distillation as an accidental impurity, and was glad I did because the bleeder tube was clogged and I had to draw a new head, but the liquid still boiled perfectly smoothly.

ezgif-7-49a7e5d58940.gif - 2.6MB

I have never gotten acetone bump on me before, but it did happen. Apparently too clean glassware and distilled and filtered acetone solution was too pure for any nucleation to occur.

wg48temp9 - 2-9-2020 at 12:39

If you want to know how good your boiling stones are let the flask or beaker boil vigorously for a few minutes then let it cool until all the boiling stops for a few minutes then reheat the flask slowly. Porous boiling stones not flooded with the liquid will stop bumping as before but plain glass and smooth glass balls probably will not.

The porous boiling stones when they contain air act like lots of small capillary tubes releasing small bubbles of gas that prevent bumping much more efficiently then any smooth glass.

Sulaiman - 2-9-2020 at 16:42

I have recently been doing a lot of EtOH distillations and for boiling stones I have been using these

STONES, from the garden - they work really well giving a stable rolling boil.

Borosilicate glass is harder than Marble and so far no signs of scratching

pneumatician - 3-9-2020 at 07:12

I distil a lot of wine & EtOH and NEVER put anything in the flask, no bumping. You put too much heat power???? Use allways the lower heat necessary, you will save yourself a lot of trouble.

Sulaiman - 3-9-2020 at 14:57

Quote: Originally posted by pneumatician

I distil a lot of wine & EtOH and NEVER put anything in the flask, no bumping.

I guess that you are doing simple distillations only, with no fractionating column?
(or possibly a poor fractionating column such as a Vigreux)

pneumatician - 3-9-2020 at 16:47

Quote: Originally posted by Sulaiman

Quote: Originally posted by pneumatician

I distil a lot of wine & EtOH and NEVER put anything in the flask, no bumping.

I guess that you are doing simple distillations only, with no fractionating column?
(or possibly a poor fractionating column such as a Vigreux)

I use in second and + distil a Vigreux of 30cm.

this guy say: from 40% to 95% EtOH in a step.

https://vimeo.com/170121935

[Edited on 4-9-2020 by pneumatician]

Sulaiman - 4-9-2020 at 06:10

Quote: Originally posted by pneumatician

this guy say: from 40% to 95% EtOH in a step.

I seriously doubt that he got 95% from 40% with that configuration.

pneumatician - 4-9-2020 at 06:31

Quote: Originally posted by Sulaiman

Quote: Originally posted by pneumatician

this guy say: from 40% to 95% EtOH in a step.

I seriously doubt that he got 95% from 40% with that configuration.

me too, :-) however next time i will try to see how that is

pneumatician - 17-9-2020 at 14:16

https://www.sciencemadness.org/whisper/viewthread.php?tid=64...

Fyndium - 6-3-2021 at 06:34

It took me a while to realize that the boiling chip element is absolutely crucial for efficient and smooth boiling for pretty much any liquid. Sometimes I got bumping so hard it effectively prevented distillation, including vacuum. The take-off rate seems to be also much higher, and even using small equipment a steady stream of liquid can be condensed, instead of drops. I've distilled 240C boiling liquids under vacuum with stream-takeoff rate.

Activated carbon.

That's the magic stuff. It pretty much always works. A teaspoon of granules in any liquid will make it go very smooth, producing an intense curtain of bubbles. A fresh load is required for every batch, including if the liquid is cooled down, as it seems that the carbon absorbs liquid and stops working.

Under no circumstances can carbon added to hot or boiling liquid. It will flash boil and blow out of the vessel. Always add it to cold liquid.

It is likely that any activated carbon will work as well. These are from brewing shop, size 2-3mm granules if I remember right.

Distillation of 110C boiling liquid:

Vacuum distillation of 240C boiling liquid:

[Edited on 6-3-2021 by Fyndium]