Not logged in [Login - Register]
 Sciencemadness Discussion Board » Fundamentals » Reagents and Apparatus Acquisition » Glassware Questions Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Detritus   » Test Forum

Pages:  1  2
Author: Subject: Glassware Questions
Thermal
Harmless

Posts: 41
Registered: 31-1-2004
Member Is Offline

Mood: No Mood

Taz - I would imagine they would be as I'm pretty sure they're meant for using with a rotary evaporator.
Quince
International Hazard

Posts: 773
Registered: 31-1-2005
Location: Vancouver, BC
Member Is Offline

Mood: No Mood

Regarding hoses, how can I connect the hose to my water tap? I still want to be able to use the tap; are there any switched splitters that will allow the type of rubber hose to be connected? Also, would there be any problem if I ran the water through the condenser and aspirator in series, to save water? Due to the fast flow the aspirator needs, I don't think the water would heat much going through the condenser, and thus vapor pressure and aspirator performance should be little affected.

\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
Magpie
lab constructor

Posts: 5929
Registered: 1-11-2003
Location: USA
Member Is Offline

Mood: Chemistry: the subtle science.

Quince:

I use a kitchen sink tap with internal (female) threads. I bought a chrome plated brass aereator with the same thread size (only male), gutted it, and soldered my brass aspirator to it.

I did the same thing for cooling water suppy only soldered a brass hose barb to the outlet.

My aspirator takes a lot of water at a high pressure. My condenser takes very little water, at a low pressure. I have yet to need to use them both at once. I suppose for vacuum distillation you would. In that case I probably would put a tee upstream of the aspirator. The line to the condenser would then require a valve to reduce pressure.

[Edited on 9-3-2005 by Magpie]

The single most important condition for a successful synthesis is good mixing - Nicodem
Quince
International Hazard

Posts: 773
Registered: 31-1-2005
Location: Vancouver, BC
Member Is Offline

Mood: No Mood

Well, I have an all-glass aspirator, so I can't solder/weld.

I don't know what else I could possibly use vacuum for other than distillation (and I guess to speed up drying).

I came up with a solution using various sizes of aquarium air tubing. Since they didn't have splitters that were large enough to provide a good flow rate, I simply cut holes in the tube sides and used that neat polyurethane glue that foams and expands as it cures to connect the other tube, making a splitter/combiner. I'll get some valves from the HW store to switch on/off different combinations. I'm going to get a bucket and a water pump that can do 30+ psi so I don't have to waste all that water with the aspirator, recylcing it instead; that has the additional advantage of providing a smoother flow rate.

[Edited on 10-3-2005 by Quince]

\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
neutrino
International Hazard

Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline

Mood: oscillating

 Quote: Originally posted by Quince I don't know what else I could possibly use vacuum for other than distillation (and I guess to speed up drying).

Vacuum filtration?
Quince
International Hazard

Posts: 773
Registered: 31-1-2005
Location: Vancouver, BC
Member Is Offline

Mood: No Mood

In pictures on Google's Image search when I type in vacuum filtration, I see the buchner funnel is put on a flat-bottomed flask with a vacuum connector. I thought flat bottoms were not supposed to be used for vacuum. What if the filter or funnel gets clogged; might not the flask break then as internal pressure falls? I have one of these but haven't tried it yet because of that worry.

[Edited on 10-3-2005 by Quince]

\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
Blind Angel
International Hazard

Posts: 845
Registered: 24-11-2002
Location: Québec
Member Is Offline

Mood: Meh!

Usually those filtration erlenmeyer have thicker wall that the normal.

/}/_//|//) /-\\/|//¬/=/_
My PGP Key Fingerprint: D4EA A609 55E4 7ADD 8529 359D D6E2 33F6 4C76 78ED
Quince
International Hazard

Posts: 773
Registered: 31-1-2005
Location: Vancouver, BC
Member Is Offline

Mood: No Mood

I guess they are also not being heated while used for filtering, though I don't know if that actually makes a difference.

\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
Dave Angel
Hazard to Others

Posts: 128
Registered: 22-3-2005
Location: UK
Member Is Offline

Mood: 0 K

Column packing

Currently, I'm going with small chunks (5-7mm a side) of broken pyrex. I took the hoarded pieces of a broken pyrex bowl, chipped them up with a hammer, then subjected them to a good shaking to round off the sharp edges.

So, a question for those of you with plain fractionating columns: what do you use for packing?
CherrieBaby
Hazard to Self

Posts: 91
Registered: 4-3-2005
Location: London
Member Is Offline

Mood: No Mood

You can get the Erlenmeyer flasks in plastic if you're worried about them breaking under vacuum.

I once made my own 5L Erlenmeyer flask using the method described in Nimble's book. (I hear there's a scanned version going around - not that I've seen it). Drill a hole near the top of a demijohn and glue a teat (see your plumbing supply section) on/in. You can stick a tube on the teat. Drilling a hole in one of those demijohn's is tedious indeed but it did work. You need a spade type drill for use with tiles. A 5L Erlenmeyer is scary to use; best cover it in plastic wrap or mesh should the unthinkable happen.

One tip is to visit your local flea market and get one of those Pyrex rolling pins from days gone by - makes a great fractional distillation column when packed with broken glass. Nice and thick too for vacuum fractionation. But doesn't fit in too well with jointed glassware. You will need to use rubber stoppers top and bottom with appropriate adaptors.

Demijohn and rubber stoppers used above - ex-wine-making supplies from the local garage sale or flea market.

Column packing - I just got loads of old flourescent light fittings and broke them carefully at either end. The white powder is easily cleaned out by shaking followed by washing. Stick them in a platic bag and gently hammer them. Use two sieves (garden centre) to get the appropriate sized glass.

Last tip is to shell out for a thermometer pocket for those vacuum distillations. I broke a flask once when the vacuum came on and sucked the thermometer into the apparatus making a neat hole in the bottom of my flask with a right mess all over my mantle as the oil leaked out. Thermometer pocket? - now you know why I want one. Don't let that happen to you.

The other trick for a vacuum pump is to get the pump from an old fridge and put that to work. Those pumps don't draw a lot of air but they do give an efficient vacuum. If you need a better vacuum from cheap pumps you can put two pumps in series.

[Edited on 22-3-2005 by CherrieBaby]
Magpie
lab constructor

Posts: 5929
Registered: 1-11-2003
Location: USA
Member Is Offline

Mood: Chemistry: the subtle science.

For my small fractionating column (22/29 gg fittings) I have found that a stainless steel scrubber pad, not packed in too tight, works very well for liquids that are compatible with this undefined type of ss. Acetic acid is not compatible with this ss and it was promptly dissolved. For acetic acid I'm going to try some glass beads. I'm also thinking of cutting up some 5mm glass tubing to make Raschig rings.

The single most important condition for a successful synthesis is good mixing - Nicodem
Dave Angel
Hazard to Others

Posts: 128
Registered: 22-3-2005
Location: UK
Member Is Offline

Mood: 0 K

Cherrie:
Your tip about the thermometer pocket may one day save the life of one of my precious few flasks, avoiding one of those altogether unpleasant "ARGGH!" moments and a post in 'tragic glassware'! Nice one, though I'm sorry you had to learn the hard way...

Magpie:
I also considered homemade Raschig's, as those I've seen for sale go for £100+ for a litre pack, so that option seems a little uneconomical. I haven't yet managed to find myself a nice, cheap glass tubing cutter though, so it's not happening right now.

I used broken pyrex for my chunks as I thought that was best considering heating being involved, but perhaps for such small pieces of glass it wouldn't matter? If so, then standard glass beads have proven much easier to track down than pyrex ones, as I guess there's not much call for thermal shock resistant jewelry!
neutrino
International Hazard

Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline

Mood: oscillating

I wouldn’t go with cheap glass, as it’s usually comprised of a lot of oxides (like sodium and calcium, thus soda-lime glass). What I think we have here is a use for Bomex. Think about it: unreactive borosilicate (or so they say) glass, very easy to break , cheap…
Magpie
lab constructor

Posts: 5929
Registered: 1-11-2003
Location: USA
Member Is Offline

Mood: Chemistry: the subtle science.

I bought a glass tubing cutter for $11 through Carolina Biological. It works quite well - a quick score, snap and you have a clean cut. CB supplies teachers so works to keep the prices down. Also you can usually buy even small items individually. You might have an equivalent supply house in the UK. I know borosilicate glass is much more resistant to thermal shock than soda-lime glass. But I don't know which is more resistant (in general) to chemical attack. The single most important condition for a successful synthesis is good mixing - Nicodem CherrieBaby Hazard to Self Posts: 91 Registered: 4-3-2005 Location: London Member Is Offline Mood: No Mood There are small supply houses in the UK but home experimenters are scrutinised more here. The relationship between the cops and suppliers is much more pally and involves the cops ensuring that suppliers "self-regulate" = squealing on any suspicious looking people. A few years back I turned up at my supplier and was surprised to see a guy I'd never seen there before who I was told was "helping out". As I negotiated my order and packed my gear, he proceeded to ask me questions, from time to time, in a nice way, about what I was doing with this gear. All very innocent looking but I wasn't fooled. I was a bit dissapointed by this because I'm not very suspicious-looking at all. But in all honesty, some of the things I got were at odds with my stated application. Cheap borosilicate is easy to pick up from flea markets. Old coffee pots do the trick, these make nice flasks (with handles even!), so one is resistant to smashing them up for the column packing. Cheap glassware - I've never had a piece of glassware fail on me. So long as it's borosilicate and has no obvious flaws I regard it as OK. Tip for buying 2nd-hand glassware - look for flaws such as tiny bubbles - those flaws will be the site where the glassware first fails. Although you can get away with using such glassware it is pretty risky. Better scrap it and get something without flaws; that can be part of the pain of using eBay. Madandcrazy Hazard to Others Posts: 117 Registered: 11-5-2005 Member Is Offline Mood: annoyed The tip for buying 2nd-hand glassware and collections by browsing the web are good. Reminders of insolvent firms, high scools and privat inserats. Cheap borosilcat glass are also good for condensers. Only much heat sensitive. Comparing the price is important. It existing some cheap offers of small firms and markets. for glassware collections. [Edited on 19-5-2005 by Madandcrazy] MadHatter International Hazard Posts: 1034 Registered: 9-7-2004 Location: Mid-Atlantic Member Is Offline Mood: Patience growing thin ! Glass Dave Angel, I use small glass beads in the reflux column of my still(Ah ! Moonshine ! ) I found them at an arts and crafts store. May not be suitable for refluxing some substances but works great for booze ! May or may not work for you but cheaper than Raschig rings. Quince, I have filtration flasks ranging in size from 250 ml to 5 L. I use 1 of those manual vacuum pumps found in most auto parts stores. For distillation I use a glass apirator. For air-conditioning applications I use a rotary vane vacuum pump. Power comes from the barrel of a gun ! Duster Hazard to Self Posts: 56 Registered: 19-7-2003 Member Is Offline Mood: No Mood I was thinking about going with a UGT distilling kit... What I did instead was look around at all the parts I would want on ebay and total up the cost.. It came out cheaper to buy them seperate (no surprise) so I ended up buying my enitre kit each piece diffrently... Heres what it looked like: 1000ml RBF from UGT 500ml RBF from Kantu Scientific 400mm Liebig from Kantu Scientific Thermometer from Kantu Scientific Thermometer Adapter from Kantu Scientific 3 way from 2 dog treasures Other kind of 3 way danrfink Hose inlet adaper from Kantu Scientific Total price was under$150 (this includes shipping).. Of course now I have spent more than $350 getting stuff... some misc. items I have gotten are a 50ml jacketed raction beaker (for$20 I couldnt pass it up), a 15kv transformer, some beakers and graduated cylinders, a triple beam balance, and some other stuff...

Moral of the story is to shop around

I even bought some chemicals (propylene glycol, sulfuric acid drain cleaner, glycerin, etc..) Now... If only I could find toluene for somewhere for less than $11 per 500ml... Duster Madandcrazy Hazard to Others Posts: 117 Registered: 11-5-2005 Member Is Offline Mood: annoyed Duster, 150$ is a small pice for the kit.
Whats the acronym UGT kit ?

I think so, it is correct shopping arround to buy chaep.
neutrino
International Hazard

Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline

Mood: oscillating

Doesn't Kantu sell mainly Bomex?
Duster
Hazard to Self

Posts: 56
Registered: 19-7-2003
Member Is Offline

Mood: No Mood

\$150 isnt too bad, a lot of the saving was from combined shipping and what not...

UGT (United Glass Tech) seels more expensive glassware but it IS better, better being thicker and all around just better. However I didnt have that kind of money to spend. I figure as time passes I will buy some more UGT and other high quality glassware as it comes. Right now I just wanted something to distill nitric with... And I think I got that.

As for the Bomex, I cant anwser that... I personally dont know, but we'll see here shortly... Whats so bad about Bomex anyway? Im curious...

Duster
neutrino
International Hazard

Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline

Mood: oscillating

I've had some bad experiences with this Chineese glass. For example, I had a 2L beaker at around 90*C. I added water (to wash it) and the entire bottom fell out. Pyrex would never do that.
Pages:  1  2

 Sciencemadness Discussion Board » Fundamentals » Reagents and Apparatus Acquisition » Glassware Questions Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Detritus   » Test Forum