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Author: Subject: The Short Questions Thread (4)
CharlieA
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[*] posted on 9-9-2020 at 17:03


Just a WAG (as opposed to a SWAG): could this be some kind of device to deliver 10 mL of a reagent from some kind of reservoir?
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B(a)P
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[*] posted on 11-9-2020 at 02:34


Some time ago I purchased a cheap condenser and it came with an addition funnel. I used the addition funnel for the first time today and it was almost impossible to get a constant drip rate. Can I replace the tap to get something usable, any tips for getting crappy taps to perform or do I just forget it?
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clearly_not_atara
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[*] posted on 11-9-2020 at 04:39


Quote: Originally posted by S.C. Wack  
The only time anyone does it (edit: should do it) cold is when they are trying to do it without glassware.

For the reaction this is true, but in order to achieve the best phase separation at workup you want the solution to be just barely above freezing IIRC




[Edited on 04-20-1969 by clearly_not_atara]
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paulll
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[*] posted on 12-9-2020 at 19:53


Has anybody ever heard of such a thing as a spring-loaded flask clamp? With how handy it would be for receiving flasks it seems to be a thing that should exist and yet I don't see any anywhere.
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karlosĀ³
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[*] posted on 12-9-2020 at 22:42


Quote: Originally posted by paulll  
Has anybody ever heard of such a thing as a spring-loaded flask clamp? With how handy it would be for receiving flasks it seems to be a thing that should exist and yet I don't see any anywhere.

Could you draw one, just a bad sketch to get the idea?
I'm not sure how that should look like.

I hope not like that: https://www.sigmaaldrich.com/content/dam/sigma-aldrich/produ...
Because that would mean they stole and produced your idea, and that in merely hours!
Those capitalist pigs, no respect on your intellectual property! :o

But seriously, like that?
Because initially I imagined a clamp to hold the receiving flask connected with the vacuum adapter(or cow) or such.
Just a plain flask clamp.
Only that I can't picture how such a thing would look like spring-loaded, which is why I was asking for a sketch of it.
And promised, not to steal the idea and sell it to sigma or whoever bids most, you have my hobby chemist word of honor on that! :D
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paulll
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[*] posted on 13-9-2020 at 18:26


Notwithstanding the fact that I can't draw with or without a computer... something like this. I'm thinking, e.g., for the receiving flask in a distillation rig - or any other flask that you'd want to change out mid-experiment.
So instead of tightening a thumbscrew to apply pressure to the piece, you'd be unscrewing it to release spring tension onto it, to hold it in place. The flask could then be removed and replaced by squeezing the other end of the clamp scissors-style. If that makes sense lol


Untitled 1.png - 12kB

[Edited on 14-9-2020 by paulll]
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Morgan
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[*] posted on 29-9-2020 at 07:54


Does anyone know a company that makes these cylindrical volumetric flasks?

https://i.ebayimg.com/images/g/QqkAAOSwg35atCrz/s-l1600.jpg
https://i.ebayimg.com/images/g/GLsAAOSwuHZatCr0/s-l1600.jpg
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Antigua
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[*] posted on 29-9-2020 at 08:02


Quote: Originally posted by Morgan  
Does anyone know a company that makes these cylindrical volumetric flasks?

https://i.ebayimg.com/images/g/QqkAAOSwg35atCrz/s-l1600.jpg
https://i.ebayimg.com/images/g/GLsAAOSwuHZatCr0/s-l1600.jpg

https://www.wilmad-labglass.com/
Here - I found them through a simple search, but they do look very expensive.

[Edited on 29-9-2020 by Antigua]
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Morgan
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[*] posted on 29-9-2020 at 15:22


Quote: Originally posted by Antigua  
Quote: Originally posted by Morgan  
Does anyone know a company that makes these cylindrical volumetric flasks?

https://i.ebayimg.com/images/g/QqkAAOSwg35atCrz/s-l1600.jpg
https://i.ebayimg.com/images/g/GLsAAOSwuHZatCr0/s-l1600.jpg

https://www.wilmad-labglass.com/
Here - I found them through a simple search, but they do look very expensive.

[Edited on 29-9-2020 by Antigua]


I see some cylindrical volumetric flasks there but not the identical shape. There are also square volumetric flasks I found that are close to it in proportion such as this one.
https://www.gogenlab.com/lab-supplies/flasks/volumetric-flas...
Just now found it.
https://kinesis.co.uk/dissolution-900ml-volumetric-flask-wit...
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Morgan
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[*] posted on 2-10-2020 at 07:01


Quote: Originally posted by Morgan  
Quote: Originally posted by Antigua  
Quote: Originally posted by Morgan  
Does anyone know a company that makes these cylindrical volumetric flasks?

https://i.ebayimg.com/images/g/QqkAAOSwg35atCrz/s-l1600.jpg
https://i.ebayimg.com/images/g/GLsAAOSwuHZatCr0/s-l1600.jpg

https://www.wilmad-labglass.com/
Here - I found them through a simple search, but they do look very expensive.

[Edited on 29-9-2020 by Antigua]


I see some cylindrical volumetric flasks there but not the identical shape. There are also square volumetric flasks I found that are close to it in proportion such as this one.
https://www.gogenlab.com/lab-supplies/flasks/volumetric-flas...
Just now found it.
https://kinesis.co.uk/dissolution-900ml-volumetric-flask-wit...


I noticed this 2 liter size is listed for $210.89 and probably shipping costs. I decided to buy that shape having found 4 of them (same Kimble 28040 flask) for sale for $34.25 each or best offer on eBay, new old stock so I bought one along with free shipping. The square flask is 5 X 5 X 18 inches.
https://www.gogenlab.com/lab-supplies/flasks/volumetric-flas...

[Edited on 2-10-2020 by Morgan]
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j_sum1
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[*] posted on 18-10-2020 at 16:56


Anyone able to give any enlightenment as to what this reaction is?
https://www.youtube.com/watch?v=cVxySCgUy8A

I thought it was a stunning demo and one I would love to add to my repertoire.
CoCl2 I have. But what is the reaction mixture being used? And what kind of complexing causes the green?
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DraconicAcid
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[*] posted on 18-10-2020 at 17:19


Quote: Originally posted by j_sum1  
Anyone able to give any enlightenment as to what this reaction is?
https://www.youtube.com/watch?v=cVxySCgUy8A

I thought it was a stunning demo and one I would love to add to my repertoire.
CoCl2 I have. But what is the reaction mixture being used? And what kind of complexing causes the green?


Might be basic peroxide and carbonate? Or basic peroxide and oxalate?




Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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B(a)P
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[*] posted on 18-10-2020 at 19:02


https://uwaterloo.ca/chem13-news-magazine/march-2014/activities/sharing-chemistry-community-colorful-catalyst

I think this is what you are after.

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j_sum1
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[*] posted on 18-10-2020 at 19:23


Quote: Originally posted by B(a)P  
https://uwaterloo.ca/chem13-news-magazine/march-2014/activities/sharing-chemistry-community-colorful-catalyst

I think this is what you are after.


Awesome. that is just great!
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SHADYCHASE54
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[*] posted on 6-11-2020 at 07:16


Hello I have a quick question regarding how to convert aniline back to actilanilide? I assum it's simple base hydrolysis? Does anyone know of a decent procedure? I have used TFSE and am coming up with nada. I would rather start from a known procedure then go the route of trail and error as I only have a small amount of the previously stated starting material; as such I would like to optimize the yield.
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[*] posted on 6-11-2020 at 07:31


Quote: Originally posted by SHADYCHASE54  
Hello I have a quick question regarding how to convert aniline back to actilanilide? I assum it's simple base hydrolysis? Does anyone know of a decent procedure? I have used TFSE and am coming up with nada. I would rather start from a known procedure then go the route of trail and error as I only have a small amount of the previously stated starting material; as such I would like to optimize the yield.

Why would it be a base hydrolysis? You have to acetylate the amine, for example using glacial acetic acid and zinc dust.
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SHADYCHASE54
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[*] posted on 6-11-2020 at 10:49


I want to convert the acetanilide back to the amine. My desired product is aniline made by reacting acetanilide, I think with a base, to convert it into aniline. Can anyone help me with this?

Thank you in advance for any help you may provide.
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[*] posted on 6-11-2020 at 11:00


Quote: Originally posted by SHADYCHASE54  
I want to convert the acetanilide back to the amine. My desired product is aniline made by reacting acetanilide, I think with a base, to convert it into aniline. Can anyone help me with this?

Thank you in advance for any help you may provide.

Now it makes more sense! In your original question you mentioned the other reaction, making acetanilide out of aniline.
Anyways, here are some sources you might find useful:
1. Hydrolysis of acetanilide, attached
2. Reactivity of Acetanilides in the Alkaline Hydrolysis Reaction: Theory vs. Experiment, attached


Attachment: article.pdf (522kB)
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Attachment: Reactivity_of_Acetanilides_in_the_Alkaline_Hydroly.pdf (533kB)
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[*] posted on 6-11-2020 at 19:35


Thanks Antigua, sorry if you found my first post unclear, regardless thanks for the reaction information you rock.

Be well.
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[*] posted on 22-12-2020 at 04:21


Hi, guys!
I have some questions that I don't think are worthy of a topic of their own. These are as follows:

1) Is it possible to concentrate a diluted solution of nitric acid (say, 10%) to its azeotrope (68%) simply by heating it, as is done with sulphuric acid?

2) When I distill concentrated sulfuric acid (98%) and KNO3, do I get fuming nitric acid that boils at 83-6 degrees or the azeotrope?

3) If, on the other hand, I use diluted sulfuric acid (30%) in the previous operation, will I get 30% HNO3 or the azeotrope?

Thanks!
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Antigua
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[*] posted on 22-12-2020 at 04:46


1. Yes
2. Fuming
3. You'd get a solution of HNO3 (less than 68%) that can be distilled fractionally or simply to get the azeotrope.
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[*] posted on 22-12-2020 at 05:20


Quote: Originally posted by Johnny Cappone  


1) Is it possible to concentrate a diluted solution of nitric acid (say, 10%) to its azeotrope (68%) simply by heating it, as is done with sulphuric acid?

2) When I distill concentrated sulfuric acid (98%) and KNO3, do I get fuming nitric acid that boils at 83-6 degrees or the azeotrope?

3) If, on the other hand, I use diluted sulfuric acid (30%) in the previous operation, will I get 30% HNO3 or the azeotrope?

Thanks!


1) In a perfect world you would boil of the water at 100 degrees, until the nitric acid reaches 68%, which would then come over at 120 degrees. In reality, depending on the efficiency of your fractionation, you will start with acid coming over a little bit over 100 degrees, slowly rising in concentration until it reaches almost 120 degrees.

The efficiency of your fractionation depends mostly on the length of your column and the speed at which you distill the acid.

2) The acid you collect from KNO3 and H2SO4 will be nearly anhydrous, but will contain a lot of NO2. I think adding water to the KNO3/H2SO4 to get azeotropic acid works better in terms of NO2 produced. You can later make anhydrous acid by adding H2SO4 to the 68% HNO3, preferably distilled under vacuum.

3) The HNO3 collected from 30% H2SO4 will behave like the acid in procedure 1. You will first collect less concentrated HNO3, followed by acid closer to the azeotrope.

[Edited on 22-12-2020 by Tsjerk]
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[*] posted on 24-12-2020 at 08:00


Just want to do a quick check if isopropanol salted-out with NaCl from 70% is safe to distill?
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[*] posted on 24-12-2020 at 08:04


Why not? Alcohols don't form peroxides like ethers.
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[*] posted on 24-12-2020 at 09:16


Quote: Originally posted by Johnny Cappone  

1) Is it possible to concentrate a diluted solution of nitric acid (say, 10%) to its azeotrope (68%) simply by heating it, as is done with sulphuric acid?


The problem is very slope concentration/boiling temperature curve, so it is like most of the acid (4/5 when you start with 50%) goes before azeotrope. The fraction 119-121 degree will contain 50-55% and only when you get the first signs of NO2 inside the condenser you can collect something around 63-68%.
I think addition of sulfuric acid could help, on rough estimation it keeps 20-30% of water by weight of H2SO4 so it will look like you will starting with more concentrated acid vapours.

Quote: Originally posted by Johnny Cappone  

2) When I distill concentrated sulfuric acid (98%) and KNO3, do I get fuming nitric acid that boils at 83-6 degrees or the azeotrope?


When NOx is present the boiling point goes down to 80-81%. You can get either red fuming or white fuming nitric acid but the latest one I believe you can get starting only with azeotrope of high purity (without vacuum). There is a lot of difference between 97.5% and 100% HNO3 (in oxidation power) and if you don't need it as a rocket oxidiser I suggest get it around 98%. This usually will be result when the equipment, the bottle and the air is not perfectly dry.

Quote: Originally posted by Johnny Cappone  

3) If, on the other hand, I use diluted sulfuric acid (30%) in the previous operation, will I get 30% HNO3 or the azeotrope?


I found that the sulphuric acid changes the boiling curve that after azeotrope the distillation returns back to the lower concentration. And in this case most of concentration will no go higher than ~45%, it only touches the maximum with few mls of the distillate and then returns back. I think the sulfuric acid try to keep so much water to become 70-75% sulfuric acid, I think you can roughly estimate the amount you need to add based on this.

[Edited on 24-12-2020 by teodor]

[Edited on 24-12-2020 by teodor]
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