| Pages:
1
2
3
4
5
6 |
watson.fawkes
International Hazard
Posts: 2793
Registered: 16-8-2008
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by Magpie  | | I did buy a second slightly larger magnet. Are you saying that if I heat the magnet in the retriever up to 80C then let it cool next to this second
magnet that I can remagnetize the one in the retriever? Is any special spatial orientation needed? |
Yep. The
only risk inherent to this procedure as such is that you don't want to heat up your other magnet above the Curie point. So you might want a simple
thermal break between the two of them. All other risks about handling small magnets apply, which is why, if you've got an electromagnet around,
they're easier to use. If you have a samarium-cobalt magnet, you could use that too, and its Curie point is rather higher.
As for orientation, above the Curie point, the magnetic domains will orient in whatever direction the externally applied field is. So you can choose
your orientation as you will, although I imagine axial is what you'll want.
As a small digression, you can get neodymium magnets in rectangular blocks with three different dimensions. These seem ideal for a science
demonstration for young children, as you can magnetize them on three different axes and it will immediately visibly apparent that the magnet is now
different. Use three magnets and they can handle them together and not rely on their memory. Since it's at boiling water temperatures, it's safe
enough for them to participate in the process without undue reliance on safety training.
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
borosilicate glass stirring rod
I often need a long stirring rod, something longer than the standard 10" variety, of which I have many. So I end up using my high temperature mercury
thermometer as it is quite long. Realizing that this is poor practice I searched for a cheap source for a long stirring rod.
What I found is that you can order Simax borosilicate glass rod in several diameters from art glass suppliers for dirt cheap. You still have to pay
the postage, however, which was about $5 for 3ea 20" rods.
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
Paddywhacker
Hazard to Others
Posts: 478
Registered: 28-2-2009
Member Is Offline
Mood: No Mood
|
|
Drying solvents after an aqueous extraction ... you can either stir in your drying agent - some anhydrous salt - or take a glass pasteur pipette, plug
the small end with a bit of cotton or glass wool, half-fill with your drying agent, and pass your non-aqueous solvent through like it was a miniature
column. The convenience is in handling and glassware usage.
|
|
|
kentkams
Harmless
Posts: 2
Registered: 18-9-2007
Location: 100.1 lat 100.2 long
Member Is Offline
Mood: calm, but frisky
|
|
come to think of it as far as tips go, Id say 2 come to mind and both are POPEYE originals. 1 if u have no running water for distillation or reflux a
small to medium bucket and a fish tank water pump (submersible). figure your pumps output to your condensers input via pvc tubing, condensers output
with tubing to bucket (use some means to hold your output tube so as to avoid litterally pissing condenser water every where. Extra cooling via ice
cubes etc.
second is the vibrator method for non vacuum buchner filtrations, which basicly halves the time of such filtrations, when vacuum sources for whatever
reason cannot be easily aquired. Method is to use some form of vibration attached to your funnel (vibrator or as ive used gamepad vibration motor).
Sorry if this seems rushed but you get the idea.
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
if you cannot afford a monomode microwave reactor and like me simply buy the cheapest convential microwave (as i find they only last 6months in the
lab) it is worth establishing immediately where the nodes are in the cavity. Convential microwave ovens form a standing wave within the cavity that
usually has a maximum (or node) in either 4 or 6 places. I find Sharp microwaves form 4 nodes that seem to correspond to 12, 3, 6 and 9 oclock
(assuming your plate is a clock) and the node is halfway between the wall and the center in these postions.
Anyway once you know where the nodes are remove the spinning plate and place your sample to be irradiated directly on the node. If however you require
a little less heating and like me you're too lazy to reduce the power (i like the one key start) then simply place your sample away from the node. I
find this especially useful for solvents that bump.
Also if you are simply evaporating off a little solvent get a good swirl going in your flask then quickly place it on the node and start.
Another trick for solvents that bump is using a conical flask about four times the volume you need and laying it on its side, when the solvent bumps
you get no lose of sample.
Does anyone have a decent method for looking into the microwave that doesn't involve placing your face onto the glass. I get a real shock when the
sample bumps.
Oh of course to establish where the nodes are place a plate directly centered in the microwave, with a few mm of water evenly over it and turn the
oven on, the water will boil in the nodes first. You naturally have to have the carosel mechanism disabled otherwise this will not work.
|
|
|
rrkss
Hazard to Others
Posts: 193
Registered: 18-12-2009
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Magpie | I often need a long stirring rod, something longer than the standard 10" variety, of which I have many. So I end up using my high temperature mercury
thermometer as it is quite long. Realizing that this is poor practice I searched for a cheap source for a long stirring rod.
What I found is that you can order Simax borosilicate glass rod in several diameters from art glass suppliers for dirt cheap. You still have to pay
the postage, however, which was about $5 for 3ea 20" rods. |
Can you U2U me the supplier, I'm in need of some longer stirring rods.
|
|
|
DJF90
International Hazard
Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline
Mood: No Mood
|
|
Panache; A more fun way to find out where the nodes are is to scatter mini marshmallows over the "floor" of the microwave (on baking paper, with the
carousel plate removed). The marshmallows melt first at the nodes, and give a clearer indication than just evaporation of water. Plus, you can munch
the melted marshmallows when you're done 
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
| Quote: Originally posted by rrkss | | Quote: Originally posted by Magpie |
What I found is that you can order Simax borosilicate glass rod in several diameters from art glass suppliers for dirt cheap. You still have to pay
the postage, however, which was about $5 for 3ea 20" rods. |
Can you U2U me the supplier, I'm in need of some longer stirring rods. |
My pleasure:
http://www.frantzartglass.com/index.php?main_page=index&...
I first bought a 7mm rod but found it too thick. So I ordered a 5mm rod - it's just right. The rod is 59" long. I had it cut in thirds for
shipping.
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
Not wanting to turn this into a 'Tips and tricks for the home Craft Hobbyists' thread, i will first defend the following post by saying the range of
skills useful in a lab are many and varied, especially when the work being performed is diverse.
Epoxies.
Very useful i have found, the following picture is of a b24-b24/b24 claisen head that i dropped resulting in a break on the male ground glass joint.
The repair would cost me 5 dollars, however it being the only claisen to b24/b24 I had at the time and the reason i dropped it was it was in use, i
needed an instant fix. I epoxied (5 minute araldite) cleanly around the remaining ground glass joint and compresssed it into a b24-b34 adaptor with
all of my considerable strength. As it is i have now had the item in use for two years, running through dishwashers cycles at least weekly with not
even a yellowing obvious within the joint. I do not use it for refluxing polar solvents (toluene)(mainly because i cannot remember
refluxing/distilling anything in a polar solvent lately(but i wouldn't if i was(wouldn't use this part that is(are the brackets confusing anyone
yet?)))).
So for those considering what to do with a near broken joint an effective, practical solution would be as just described.
For mixing and applying the epoxy use a polypropylene freezer bag, squirt the 2 part epoxy into the very corner, then mix using the shearing action
of the two counter surfaces of the bag, once mixed squeeze the ready to apply epoxy to the corner where a tiny nick will convert your bag into a
piping bag.
|
|
|
UnintentionalChaos
International Hazard
Posts: 1454
Registered: 9-12-2006
Location: Mars
Member Is Offline
Mood: Nucleophilic
|
|
That's still a bit pricey. I bought 5lbs of 6mm borosilicate glass rod off ebay for chump change. There are a few bubbles, but nothing worth
complaining about for the price. I feel like the 6mm is a better size than the 5mm, but that's probably just me.
See here: http://www.sciencemadness.org/talk/viewthread.php?tid=12494#...
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
Glassware often has little glass hooks welded close to the join. This enables joins to be attached together via the use of small springs. Typically in
situations where something is to be left unattended but there may be slight pressure build ups the springs serve as a sort of pressure release valve
by allowing the joint to open slightly, depressurise, then snap back.
Unfortunately much glassware is without the hooks (or they face in the wrong direction for your purpose, or one is broken), an easy fix for this is to
slide one or two snug but not tightly fitting o-rings over the section just past the ground glass joint, then fit a hose clamp over these and tighten
tightly enough to hold the springs.The oring allows for expansion in both the hose clamp and glass and also raises the hose clamp such that it has a
lip to hook your springs to.
|
|
|
Skyjumper
Hazard to Self
Posts: 93
Registered: 1-3-2010
Location: Assachusetts
Member Is Offline
Mood: Refluxing
|
|
Store Butyric acid in a double bag to prevent leaks. Trust me /hint
|
|
|
chemrox
International Hazard
Posts: 2961
Registered: 18-1-2007
Location: UTM
Member Is Offline
Mood: LaGrangian
|
|
old fashion glass curtain rods, about 12mm diameter, with expanded ends make nice stirring rods when the need is for a really long one. I picked up a
couple of these at the thrifts for a dollar (US). The expanded ends are rough and good for scratching beakers to promote crystallizations.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
powder addition is always a pain, the years have not really improved things very much, there's a tricky screw thread type piece of glass which when
turned coaxes the powder along a barrel from a small glass hopper, i have never used one of these but they intuitively look too complicated. Normal
powder addition funnels (basically a dropping funnel with a ground glass joint at the bottom instead of a tap are just crap.
Anyway a neat way around all this silliness is to use a balloon, fill your powder into the balloon place the balloon over the joint where the addition
is meant for. You may then leisurely coax the powder into you system with the fine control of your fingers with no having to constant open the system,
if the joint clogs up a bit you can use a gloved hand to squash it down.
Because i'm careful i usually use a double balloon. If your system is particularly aggressive a couple of polypropylene freezer bags within the
balloon work well.
|
|
|
UnintentionalChaos
International Hazard
Posts: 1454
Registered: 9-12-2006
Location: Mars
Member Is Offline
Mood: Nucleophilic
|
|
As to the above, I have one of the screw-type addition funnels and they are also a pain to use. They work great on small prills or flakes. fluffy
powder, not so much. The main problem is that it refuses to move down into the screw assembly and also that you can't really have refluxing solvent or
the powder ends up clumping and sticking to the walls.
To solve the not-free-flowing issue, I throw a stirbar into the main chamber and then use a neodymium magnet on the outside to knock powder down into
the screw. As for the sticking to the walls, I sure hope you don't need every single grain of the stuff! You might want to try voodoo.
I suspect the bags you speak of are not very vacuum-friendly though, which is no problem for the glass.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
|
|
|
Ephoton
Hazard to Others
Posts: 463
Registered: 21-7-2005
Member Is Offline
Mood: trying to figure out why I need a dark room retreat when I live in a forest of wattle.
|
|
I have a tip  .
when doing a reflux reaction that then needs distilling afterwards I use a liebig condensor as a fractionating collumn in a distillation setup then
connect the output of the distillation condensor to the bottom of the liebig to reflux.
I use two hoses with a glass tube in the middle between the distillation condensor and the liebig.
I then just need to disconnect the distillation condensor from the liebig to stop refluxing and then distill.
this stops the liebig from spilling out over my mantle and stops me from having to crack the system open.
e3500 console login: root
bash-2.05#
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
| Quote: Originally posted by Ephoton | I have a tip .
when doing a reflux reaction that then needs distilling afterwards I use a liebig condensor as a fractionating collumn in a distillation setup then
connect the output of the distillation condensor to the bottom of the liebig to reflux.
I use two hoses with a glass tube in the middle between the distillation condensor and the liebig.
I then just need to disconnect the distillation condensor from the liebig to stop refluxing and then distill.
this stops the liebig from spilling out over my mantle and stops me from having to crack the system open. |
i must have it wrong in my mind, why not simply use the liebeg as a condenser during reflux and then afterwards turn off the cooling water supply to
it before slotting a distillation setup on top of it? This has all the advantages of yourr described method minus the need to use that hose/glass tube
return.
|
|
|
Ephoton
Hazard to Others
Posts: 463
Registered: 21-7-2005
Member Is Offline
Mood: trying to figure out why I need a dark room retreat when I live in a forest of wattle.
|
|
becouse I dont like unplugging the condensor when its got a mantle under it.
plus I like to have the whole setup put together before I start the way I do it I just need to detach the
two tubes and it changes from reflux to fractional distillation with out me slotting glass together.
the reaction im playing with some times if your not carefull swamps the reflux condensor as well this way
you can not get anything on your mantle it will just in the worst case fill your reciver.
also if you were to do a reaction that gave off nasty fumes and then needed to distill it you can use
the vacuum take off adapter as your gas outlet and lead it to a gas trap. then when you distill you dont
have to brake your system to the air out side. its better this way too for inert atmospheres to I would think.
I do chemistry were I realy should not allow smells to be a problem.
I find the worst smells are when I am chaning setups over from a reaction to a distillation as at these points in time I have very little protection
from the vapour given off.
yes I should get my self a fume hood but at the moment I
dont want one were I am.
I dont make smells this way either.
[Edited on 17-4-2010 by Ephoton]
e3500 console login: root
bash-2.05#
|
|
|
Lambda-Eyde
National Hazard
Posts: 857
Registered: 20-11-2008
Location: Norway
Member Is Offline
Mood: Cleaved
|
|
It's probably mentioned all over the forum, but if you have a frozen glass joint, some toluene or similar solvent applied with a pasteur pipette will
seep into the joint and allow you to free it up with some force. Remember to apply grease to the joint afterwards if it's a stopcock.
I just did this with an addition funnel that was completely frozen, and it worked wonders.
|
|
|
SWilkin676
Hazard to Self
Posts: 68
Registered: 3-2-2010
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by kentkams | come to think of it as far as tips go, Id say 2 come to mind and both are POPEYE originals. 1 if u have no running water for distillation or reflux a
small to medium bucket and a fish tank water pump (submersible). figure your pumps output to your condensers input via pvc tubing, condensers output
with tubing to bucket (use some means to hold your output tube so as to avoid litterally pissing condenser water every where. Extra cooling via ice
cubes etc.
. |
I used a plastic ice chest/cooler and attached hose barbs to the front and a hole in the side for the pump cord. That way the ice stays cold longer
and junk doesn't get into the water. To empty I just open the cooler drain outlet into a bucket.
|
|
|
SWilkin676
Hazard to Self
Posts: 68
Registered: 3-2-2010
Member Is Offline
Mood: No Mood
|
|
Canning Funnel
When I'm putting herbals and powders into large wide mouth jars, I had trouble with the stuff sticking - even with a powder funnel. I made a
makeshift funnel by cutting the end off a plastic bottle that had a wide mouth to it. Later I found that canning funnels are just what you need -
they come in plastic and stainless steel. I also found a neat little gizmo used in canning for lifting lids that is basically a plastic stick with a
magnet mounted to the end that works ok for stir bar retrieval (as long as the chemical isn't really nasty).
[Edited on 10-5-2010 by SWilkin676]
|
|
|
franklyn
International Hazard
Posts: 3026
Registered: 30-5-2006
Location: Da Big Apple
Member Is Offline
Mood: No Mood
|
|
Reflux on a shoestring
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
| Quote: Originally posted by aonomus | | Another thing with gallium is that it wets glass unlike mercury, wouldn't that make it a pain to clean off? |
Actually, I have quite a bit of experience with gallium. You can use an alloy of about 70% gallium, 20% indium, and 10% tin to make a metal that's
liquid at room temperature. This will alloy with aluminum and expose it to the environment. However, this doesn't work nearly as well with eutectic
aluminum alloys, it works much better with pure aluminum. Aluminum foil is fairly pure, but is too thin with too many layers of oxide that need to be
eaten through. Aluminum muffin tins are probably the cheapest, best consistent source of pure aluminum I know about.
Also, the gallium alloy can be reused. Dilute HCl or a dilute NaOH solution will make the gallium alloy suddenly ball up on glass. It's actually
quite cool to watch. It can then be extracted much easier. If there's a lot of aluminum by-products nearby, they can generally be dissolved by
dilute HCl, or even strong HCl for that matter, since even strong HCl doesn't dissolve gallium very fast. The gallium then forms drops on the bottom
that do not stick to glass as long as HCl concentration is maintained.
Additionally, the gallium/aluminum mixture can be made a lot more active by melting the two together with a torch first. The only downside is that
gallium is expensive. The best I've managed is $2 a gram for 50 grams, and a gram of gallium isn't much. For comparison, silver costs less than half
that.
[Edited on 5/26/10 by Melgar]
|
|
|
Chainhit222
Hazard to Others
Posts: 138
Registered: 22-8-2009
Location: peach's mailbox
Member Is Offline
Mood: grignard failing to start
|
|
I have never seen this done before, but I think it is a useful laboratory technique.
Normally in the distillation of a volatile solvent, you have some losses through the little vacuum nipple on the adapter you use behind the condenser,
I notice a design exists for a jacketed adapter (so you can pass water through it like a condenser, I believe I have found an easier solution.
I broke my 105 degree vacuum adapter by accident, but I happened to have a double female 3 way adapter, so I have devised this setup (Used it for
ether thus far, seemed to work well)
I attached the Frederich's style condenser to the top female joint of the 3 way adapter (where the thermometer would usually go) and I linked it to my
other condenser in series. This way if any liquid vaporizes in the reviving flask, it gets refluxed by the condenser on top of it. I'm not quite sure
how effective this method is, or if the losses are even significant through a vacuum nipple, but I believe I have noticed a reduction in odor (when I
turn my fume hood off that is).
Picture: http://img179.imageshack.us/img179/4849/ether3.jpg
[Edited on 27-5-2010 by Chainhit222]
The practice of storing bottles of milk or beer in laboratory refrigerators is to be strongly condemned encouraged
-Vogels Textbook of Practical Organic Chemistry
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
Is that a retort made from a length of steel rod and an old brick? Fantastic! Whats the motor sitting behind the setup for?
|
|
|
| Pages:
1
2
3
4
5
6 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
