CarlJ
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Newbie questions
Let me start by saying i have very little practical experience with chemistry so please have patience if i say/ask something stupid.
I've had an interest in the subject for some years and recently bought some lab ware including some 24/29 distilling flasks and condenser. I ordered a
thermometer pocket online thinking it would be like a socket i could slip my thermometer in to read the temperature at the Y section of the still head
however it isn't.
This is a pic:
http://img188.imageshack.us/i/pocketf.jpg/
It's too big to hold a thermometer on it's own and the 'finger' on it extends all the way into the neck of the boiling flask, I'm also guessing I
wouldn't get a correct reading since the thermometer wouldn't be in contact with the vapor. So what is it used for? What do i need to fit a
thermometer in it? and what is the name of the piece I actually need (so i can accurately read the temp while maintaining a 100% glass setup)?
Also, I have yet to buy an adapter to connect my 24/29 condenser to 24/29 receiving flask since I'm not sure what I'm looking for. I would like to try
vacuum distillation once i get a handle on simple distillation so should i buy a vacuum adapter? Can i use that for standard as well as vacuum
distillation or do i need two separate ones?
What would be a good way to get used to using a distillation setup? I was thinking of getting a cheap bottle of wine and boiling off the ethanol.
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User
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The comparison with a finger could well be not so far off, it somewhat looks like a "cold finger" finger, look it up.
A thermometer with a ground piece is very nice.
One can also buy adapters with one ground part and a rubber ring so that any thermometer can be slid in (not very good at high temp or with certain
chems.)
Ethanol/water would be a good start it also was my first destl. run, also there are quite some physics involved.
What a fine day for chemistry this is.
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not_important
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What you have is a thermometer well, usually used for measuring the temperature in a multi-neck flask. The well is inserted into one of the necks,
and filled with a fluid compatible with the temperatures to be used; generally a silicone oil used used. Then the thermometer is place into the well,
often it is first inserted through a stopper to hold it a bit above the bottom of the well.
You want a thermometer adapter, plus possible thermometers with ground glass joints on their body. There are two main types of adapters, one
that takes ordinary thermometers that get inserted through some sealing material, and another that adapts the lower ground glass joint to a small ST
joint - generally 10/30 - to match a joint on the thermometer.
The first type comes in several versions, the better ones have threading on the top section and a matching cap that is tightened down to compress an
O-ring or washer surrounding the thermometer. Simpler versions just use a rubber stopper or a rubber cap with a hole in it for the thermometer, these
are not as good for vacuum or corrosive gas applications.
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one form of the first type of adapter:
http://www.aceglass.com/page.php?page=8300
the real simple version of the first type, not for reduced pressure or nasty stuff
http://www.aceglass.com/page.php?page=9095
often used with this sort of thing
http://www.aceglass.com/page.php?page=9554
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one style of the second type
http://www.aceglass.com/page.php?page=5021
another style, just the 10/30 top size
http://www.aceglass.com/page.php?page=5000
and a fancy one
http://www.aceglass.com/page.php?page=5100
for those you need thermometers similar to these, note the ST ground glass joint low on the stem
http://www.aceglass.com/page.php?page=8314
[Edited on 12-8-2009 by not_important]
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CarlJ
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Thanks for the replies, you've helped a lot  .
Just to make sure I understand, I need to get one of these: http://www.aceglass.com/page.php?page=5000 with a 10/30 top and a 24/40 bottom?
How are those measurements taken? I understand 24/29 is a taper with 24mm at the bottom and 29mm at the top. I was given a condenser that was said to
be IIRC 24/40 but it doesn't have ground joints?
And one of these: http://www.aceglass.com/page.php?page=8314 But how do i know which length I need? Is it from the top of the joint to the tip of the bulb, or the
bottom of the taper to the center of the bulb? Will i need to have my adapter before i determine which thermometer I need? Also is that a typical
price for ground glass thermometers? $44 seems rather high given that a normal one is around $3, I only paid $40 or $45 for my 1000ml 24/40 RB flask
[Edited on 12-8-2009 by CarlJ]
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starman
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Quote: Originally posted by CarlJ  | Thanks for the replies, you've helped a lot .
How are those measurements taken? I understand 24/29 is a taper with 24mm at the bottom and 29mm at the top. I was given a condenser that was said to
be IIRC 24/40 but it doesn't have ground joints?
[Edited on 12-8-2009 by CarlJ] |
24/29 is 24mm diameter 29mm is the length, the taper is a set degree.24/40 only difference is that it is 11mm longer,same standard taper,they can be
used interchangably.If you are looking at distillation seriously a ground glass jointed condenser is a must,otherwise you may as well just use a
stopper with a hole for the thermometer as your set up is dependant on its weakest link.
$44 for the ground glass thermometer not so bad a price,they seem an expensive item regardless of supplier.
Chemistry- The journey from the end of physics to the beginning of life.(starman)
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CarlJ
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Thanks, looks like i need to do some more shopping.
I have two condensers, one 400mm that was given to me without GG joints and a smaller 300mm one with 24/29 joints, so I might just sell the plain
400mm one and use the money for another 24/29 condenser or flask.
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psychokinetic
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I seem to be in a similar boat as you, there. The shopping just keeps on a'comin'!
I'm just in the process of figuring out what I need and getting clearance to buy restricted items. Bit of a worry really.
Anyway, on topic: Have you found the stuff you need?
“If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found
the object of his search.
I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”
-Tesla
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