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Quince
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Regarding the use of home glassware as lab glassware
Or, how I learned not to do it the hard way
So there I was, getting ready to boil some drain cleaner to concentrate the sulfuric acid (though it's already pretty good). As I had done a few
times before, I poured it into the same old drinking glass, about a third full, and put it in the microwave. Within ten seconds, I hear a slight pop.
The portion of the glass starting within a few millimeters above the liquid level broke off cleanly, leaving a pretty level cut. Incredibly, no acid
was spilled, though it was almost to the brink of the bottom of the glass.
Oops.
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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cyclonite4
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I had a similar event when I was using regular glassware to boil down H2SO4 on a portable gas stove, and the glass cracked and fell apart, pouring
acid on the table and fucking up my stove. Luckily I only had 400mL boiling, so the problem wasn't too severe.
Anyway, the proper glassware is always worth the extra bucks (although most of mine was free  ).
[Edited on 12-2-2005 by cyclonite4]
\"It is dangerous to be right, when your government is wrong.\" - Voltaire
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ilovechemistry
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besides problems with heating and breakage, are there other negatives of regular glassware? can household glass products effect chemical processes?
for example instead of beakers and RBFs, could i stock my lab with mason jars and wine jugs?
thanks,
ilovechemistry
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ScienceGeek
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I don't understand how someone can use "regular glassware" to heat something.... In my opinion, that is just aksing for something to go wrong.
When it comes to storage, though, regular glassware usually suffice. Just don't do anything stupid like storing HF in regular glassware....or any
glassware...
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ShadowWarrior4444
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Pyrex brand cookware is useful for heating things, and naturally for boiling acid.
Perhaps glazed ceramic may be useful as well.
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starman
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In the microwave?How would that go for time/economy versus open dish on hotplate?
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ScienceSquirrel
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Heating sulphuric acid in a ordinary table glass in a microwave oven sounds a bit bats to me.
Microwave ovens can superheat liquids to above their boiling point. Picking up a glass full of superheated sulphuric acid could cause it to 'bump' out
of the glass.
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jokull
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| Quote: | Originally posted by ShadowWarrior4444
Pyrex brand cookware is useful for heating things, and naturally for boiling acid.
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You can bet this an excellent option. In fact, sometimes I have used such pyrex for lab applications when high volume is needed with a fair price.
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kilowatt
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Newer "pyrex" brand cookware is just regular soda-lime glass, not borosilicate. Assuming it can take the heat/thermal shock while processing "high
volume" could be a disaster waiting to happen.
The mind cannot decide the truth; it can only find the truth.
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h2o2guru
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Just a quick note , I use a LOT of Ball/Mason type jars for chemical storage, they usually hold about 1Kg (pint)and if you use a white plastic cap are
quite nice. Cap's are available at some wallmart's and also amazon.
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MagicJigPipe
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"Pyrex brand cookware is useful for heating things, and naturally for boiling acid."
This is COMPLETELY false and it might get someone seriously injured. Pyrex brand cookware is THE WORST possible thing you can use for boiling
sulfuric acid. It will survive the heat but once it cools it WILL shatter. Almost every time.
DO NOT use Pyrex cookware (like as is sold at Wal-Mart) for ANYTHING that involves heating to high temperatures (say above 100C). I mean, it
specifically says to not place it on a cooktop. It can't get any more obvious than that.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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ScienceSquirrel
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Anyone mad enough to boil sulphuric acid in Pyrex brand cookware should be given a Darwin award in advance.
Chemistry: Nature's way of thinning out the world's population of idiots!
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12AX7
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My Pyrex bowl (I think it's got to be 20 years or older FWIW) seems to do just fine over flame. Haven't had a failure yet. Before I got it, it
survived many a microwave jello synthesis.
Tim
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S.C. Wack
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[of course when they speak of Pyrex here, the name applies to kitchenware only]
"Pyrex originally was made of borosilicate glass, a Corning invention, that enabled it go from the oven to the refrigerator and vice-versa.
Pyrex in Europe is still made of this type of glass.
Around 1946, Corning began making some Pyrex out of tempered soda lime glass. World Kitchen tells the 2 Investigators most Pyrex sold in the U.S. has
been made of soda lime glass since that time., and that the transition was completed by 2001.
"Both versions of Pyrex glass bakeware were made to meet similar performance attributes and were safe for consumer use," World Kitchen said in a
letter.
Professor Bradt says the glass as it's presently tempered is "very much more susceptible to fracture or breakage from temperature changes than the
original Corning Pyrex, which is the classical oven-to-icebox glass.""
http://cbs2chicago.com/seenon/problem.with.pyrex.2.664614.ht...
The exploding Pyrex is not a myth, I've seen it myself.
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12AX7
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Hmmm, tempered soda-lime, that means it will literally explode. Lovely...
Tim
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matei
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| Quote: | Originally posted by 12AX7
Hmmm, tempered soda-lime, that means it will literally explode. Lovely...
Tim |
Also soda-lime glass (which is ordinary glass from which windows, jars, etc. are made) is less resistant to chemical attack than borosilicate. What I
find surprising is that they are allowed to sell soda-lime glassware under the trade name Pyrex (which I myself thought is synonym with
borosilicate)...
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MagicJigPipe
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Yes, I was ABSOLUTELY APALLED by the fact that they could be allowed to sell shitty soda lime glass as "Pyrex".
It does literally "explode"! I had this happen before. (about 6 years ago). I was boiling some H2SO4 in a "Pyrex" dish on a hotplate. It was fine
all the way up to and over 300*C but about 2-3 minutes after I turned of the heat I hear a slight "pop". Well, needless to say 90%+ extremely hot
H2SO4 went everywhere creating a huge mess. If I were near it I could have been seriously injured.
Yes, I assumed is was borosilicate because of the name. But give me a break guys, I was only 18. (I was wearing a lab coat, full length gloves and
safety goggles)
Anyway, I've done other experiments w/ it and I can say beyond a shadow of a doubt that it is a horrible thing to use for direct/high heating. In
the oven, it's okay. Elsewhere, ditch that shit.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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DerAlte
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@S.C.Wack
| Quote: | | Around 1946, Corning began making some Pyrex out of tempered soda lime glass. World Kitchen tells the 2 Investigators most Pyrex sold in the U.S. has
been made of soda lime glass since that time., and that the transition was completed by 2001. |
S.C., are you sure of that date? I knew that Corning gave up the manufacture some time ago to whoever, and that subsequently cookware labelled as
'oven safe' had problems, but I have been using a Pyrex saucepan (pinky color) for about 12 years over naked burners and in microwaves at temperatures
close to 300C without the slightest problem. I always assumed that "Pyrex' and borosilicate were synonymous and that Corning would never let their
trademark be used for an inferior product. I also use (for lower temperatures) Corelle ware, which is a layered and tempered glass for such functions
as evaporation dishes, but not on open flame. I have never had one crack in a microwave or on a sandbath.
Are you sure that Corning allows soda - lime glass to be sold as 'Pyrex'?
WRT using glass jars, etc. they can be used, with care, but not for naked flame or electric rings or hot plates. You must use a water bath. I have
also used them frequently in jam and marmelade making, where the sugar content takes the liquid well above 100C. In that case one pours the hot jam
into oven heated galss. Glass jars can crack in the microwave under certain conditions ( drying liquids) but can be used in the freezer at low temps,
even as the liquid freezes. The one thing they cannot stand is temperature shock.
Regards,
Der Alte
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MagicJigPipe
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Where do you live DerAlte. UK? (I'm guessing because I thought I saw you use the acronym "FA". Forgive me if this wasn't you).
Anyway, this could be the reason that your "Pyrex" is actual Pyrex. I will take a picture of the glassware I'm talking about. It is MOST CERTAINLY
not a Corning product in the US.
Okay, I found a picture. This might not be the EXACT product that I used (because it's been many years) but it is definitely similar. I know how
borosilicate behaves and I know that this shitty, inferior product IS NOT borosilicate. It sucks. It breaks--shatters--under the slightest thermal
stress (cooling from 300 to 200 C slowly).
However, for some reason it works fine in the oven for most things...
Also, the ovenware not in the picture reacts the same way.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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S.C. Wack
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The Visions and Corningware brands are pyroceramics that apparently do not contain boron. Just use real lab glassware, people. I doubt that Corning
gives a shit about the business that they are no longer interested in being part of. They built up a brand name worth lots of cash, and they sold the
name for lots of cash. Of course the new buyer is expected to lower costs in order to make up for this. That is how it works. Whenever someone sells a
brand name to someone else, the product always changes for the worse.
[Edited on 17-8-2008 by S.C. Wack]
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ScienceSquirrel
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Real lab glassware can be acquired a few bits at a time.
You do not need a lot to start with and it is not that expensive if you shop around. I have got lots of flasks etc in good condition from eBay.
And another thing is no one will be tempted to borrow things.
So it means that you will not be coming home to your favourite fish pie with crispy cheese top and half way through your second portion and the third
beer realise that the pie dish bears an uncanny resemblence to the one that you used to recrystallise that big batch of lead nitrate the previous
week...
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grndpndr
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Ive used the 'bomex'(brand name?) borosilicate glassware w/o any major malfunction for years bought through American scentific and surplus.Selections
very limited beakers, flasks,seperatory funnel,glass funnels,grad.cylinders all with satisfactory results and the $ is more than reasonable,mason jars
seem ok for some less rigoruous applications and with some mild thermal usess such as hot water baths but with toxic/caustic materials the chinese
borosiicate is the minimum Id trust and thats ouside if hot sulfuric acids involved. cant envision a beaker of hot H2S04 breaking in the
kitchen/microwave?.I rarely use my glassware over flame most often hotplates with sand and water/oil baths nice catch in case of breakage.
In any event I notice the selection(chinese 'bomex') has dwindled to the very basics, flasks and beakers mainly.
[Edited on 18-8-2008 by grndpndr]
[Edited on 18-8-2008 by grndpndr]
[Edited on 18-8-2008 by grndpndr]
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497
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I've boiled down battery acid in a 1 L bomex flask at least 10 times with no problems. At first I tried to use sand baths and such, but it was always
a mess and used a lot of propane (I use a little cheap portable single burner stove). Now I simply set the flask directly on a low flame and then turn
it on high after a few minutes. It goes fast and always works well. Maybe I'm just lucky that it hasn't broken.
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grndpndr
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In the case of hotplates ive been taught/read always use some kind of spacer between beaker/retort etc and heat.Even a screen is adequate and maybe
its habit but in the case of retorts/ round bottom flasks a sand bath holds them relatively securely w/o added expense of a ringstand.
Although ive mprovised one for my seperatory funnel.Anything that can be safely improvise Im obliged to do so.Even in the case of imp. distillation
apparatus although slow and some minor pieces (hardware pvc tubing and pvc tape)need replaced every few runs it ok for small amounts of concentrated
nitric acid.
Anyone had experience with the glass dstillation retorts?A older (40s-50s) chemistry book has the retort as a std distillation setup for nitric acid
w/a snug fitting small round bottom flask as the reciever in an ice bath.The modern retorts ive seen w/glass stoppers are 1/4 the price of a
traditional all glass dstillation set-up and as nitric is my only use for a distillation rig im tempted If they work as advertised
even though 70% nitric is available delivered(im on the del. trucks run) for $36/2.5L no telling how long that will last.
[Edited on 18-8-2008 by grndpndr]
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DerAlte
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Magic-Jig said:
| Quote: | Where do you live DerAlte. UK? (I'm guessing because I thought I saw you use the acronym "FA". Forgive me if this wasn't you).
Anyway, this could be the reason that your "Pyrex" is actual Pyrex. I will take a picture of the glassware I'm talking about. It is MOST CERTAINLY not
a Corning product in the US. |
I live in the US and got the thing at K-mart, some 12 years ago, I guess. As for using the acronym FA, I may have done - I was born in UK and lived
there until 1964. The polite form is 'sweet Fanny Adams' but that ain't what it stands for = 'nothing'.
The item is not like anything you showed. It's amber color, rather than pink as I said above. The thing in a whole 5mm thick on the sides and
assumedly the same on the bottom. It does not actually say 'Pyrex'...
@S.C.Wack
... It is marked Visions. It was by Corning, if my memory is correct. I also have some genuine Corning Ware white ceramic stuff, and I understand that
this is a calcium aluminate composition, opaque white. I'll vouch that that stuff can be gotten red hot and quenched without cracking.
The Visions saucepan is clear amber. It may not be borosilicate, as you say. I was very wary at first of heating such a thickness of a glass on an
open flame or red hot burner, but have done so over time repeatedly, even leaving it past the evaporation point so that it got very hot, fusing the
salt in it. It seems pretty resistant to hot alkali too. I have used it to evaporate to dryness CaCl2 in both microwave and over a burner. It must
have a coefficient of heat expansion at least as low as, if not lower, than borosilicate.
The Corelle stuff is a layered, tempered glass and also may well not be borosilicate. I never heat this on open flame but on a sandbath and have never
had this crack, either.
Der Alte
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