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DraconicAcid
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[*] posted on 16-5-2016 at 14:22


Quote: Originally posted by glymes  
Why is it that there are a lot of organic nitrates (nitrotoluene, nitrobenzene etc.) but virtually no chlorates of the same ilk? This interests me.


Nitrobenzene is not an organic nitrate; phenyl nitrate would have an oxygen between the carbon and the oxygen.

Perchlorylbenzene does exist (http://pubs.acs.org/doi/abs/10.1021/i360060a011 ), but it takes courage to work with such materials.

Prep: https://books.google.ca/books?id=vD-qCgAAQBAJ&pg=PA624&a...

Who the hell wants to work with perchloryl fluoride in order to make the compound?




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[*] posted on 16-5-2016 at 14:40


Nitrotoluene and nitrobenzene are not nitrates, they are nitro-compounds.

Nitrates have structure R-O-NO2.
Nitro's have structure R-NO2
Nitrites have structure R-O-NO (isomers of nitro's)

Organic nitrates are not that stable. There are a few (e.g. glycerine trinitrate) but these are sensitive explosive compounds.
Organic chlorates simply are too unstable to exist. Chlorate only is stable in ionized form, as ClO3(-). The covalent HClO3 does not exist, chloric acid only exists in aqueous solution up to appr. 40% in which it is fully ionized to H3O(+) and ClO3(-). Organic chlorates would be covalent and hence they are so unstable that in practice they do not exist at room temperature.
The ionization of chlorate stabilizes the ions by means of resonance. The covalent chlorates do not have this advantage.

A similar thing exists for perchlorates. Ionic perchlorates are very stable, covalent perchlorates are unstable. E.g. anhydrous HClO4 does exist, but is extremely dangerous, as it can explode without apparent reason. Aqueous HClO4 on the other hand is quite inert and hardly shows oxidizing properties, just acid properties.
There are a few organic perchlorates though. Someone on sciencemadness has actually done some experiments with organic covalent perchlorates. IIRC this was user axt, who did experiments with ethylperchlorate. I myself have made quite a few organic perchlorates, but all of these are salts of amines, or complexes of metals with organic ligands, with the perchlorate ion as anion.




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glymes
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[*] posted on 16-5-2016 at 22:10


AXT had the ethyl perchlorate 'spoon shot' didn't he (where a drop of ethyl perchlorate blew a metal spoon out of his hand?) Ethyl perchlorate looks very nasty.Apparently, methyl perchlorate is more unstable, more explosive and around as toxic as dimethyl mercury.
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[*] posted on 18-5-2016 at 05:08


Why do alchemical manuscripts always show tons of different still head while we modern chemists only have one and a couple different condensers?

Photos: "1606" https://en.wikipedia.org/wiki/File:Alembics_from_Andreas_Lib... "2016" https://commons.wikimedia.org/wiki/File:Simple_distillation_...
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[*] posted on 19-5-2016 at 13:22


When So2 gets dissolved in water it forms the unstable sulfurous acid, what does it decompose into if it is unstable?
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[*] posted on 19-5-2016 at 14:31


Quote: Originally posted by Jstuyfzand  
When So2 gets dissolved in water it forms the unstable sulfurous acid, what does it decompose into if it is unstable?

Sulphur dioxide and water.




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[*] posted on 20-5-2016 at 13:02


Thank you
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[*] posted on 23-5-2016 at 04:58


Question


Does an iron nail displace cobalt ions from CoSO4 solution?
Will it form FeSO4 and Co metal?
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[*] posted on 23-5-2016 at 08:44


Cobalt(ii)'s standard reduction potential is -0.28 V, and iron(ii)'s is -0.44 V.

Therefore, yes.




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[*] posted on 23-5-2016 at 10:01
TinSandwich


It looks to me that some are simple still heads, also I see equivalents to;

. anti-splash function
. fractionating function
. condensing/refluxing function

it appears that some were for specific processes such as mercury distillation,
just as some manufacturing stills look quite different from lab versions.

if anything we now have more complex arrangements;
flask capacity, shape, wall thickness, number and type of neck
column types
still adapter types
condenser types
take-off types
receiving flasks
rotovaps, pig adapters, stirrers, perkin triangles, pressure-equalised funnels ..............

I want ALL of them :D

and I think an alchemist of times gone bye would freak out if he was given a Quickfit catalogue to choose from :o


[Edited on 23-5-2016 by Sulaiman]
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[*] posted on 23-5-2016 at 10:06


Quote:
Quote:
When So2 gets dissolved in water it forms the unstable sulfurous acid, what does it decompose into if it is unstable?

Sulphur dioxide and water.

Sulphurous acid is unstable because air slowly oxidises it to H2SO4!

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[*] posted on 23-5-2016 at 12:44


Quote: Originally posted by Sulaiman  
I want ALL of them :D

What for ?




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[*] posted on 24-5-2016 at 15:24


I thought at first he was wanting all of the styles of stillheads combined. that would be a sight to see...



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[*] posted on 24-5-2016 at 15:24
Distilling - question about condenser


I'm curious how to tell whether all the gases that come through a condenser and out any "extending" hose has captured all available liquids/gases. Let's use ethanol as an example. The temp of the condenser is 70 degrees F and the temp of the gas coming out the end of the 12" hose at the end is 85-115 F.

The thing is that at times when distilling I'll hold the hose in a "U" shape, fill it with condensate, and watch to see if gas vapors pass/push through.

It seems that at times the gas pushes through and I see a mist on the collecting vessel but the temp is 100F where the evap point is ~170.

Is it possible that there is still something in gaseous form at those temps?

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[*] posted on 24-5-2016 at 15:30


Well, when you boil water, it can condense in the air as a mist....but if the so-called mist is a gas still (punintended), then it's possible the gas simply hasn't liquified yet. Cooling down and condensing and coalescing into a liquid in a flask take time.



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[*] posted on 27-5-2016 at 08:24
Seperation of sodium sulfates


I have a mixture of sodium sulfate and sodium bisulfate, the former of about 5% by weight. I need to get rid of those 5%, and I was wondering if there was a solvent that only one of these two is soluble in, or if I have to do a recrystallization, and if so, which solvent would be preferrable to do so.
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[*] posted on 27-5-2016 at 08:50


Make a solution of your contaminated bisulfate and add excess sulfuric acid. From this solution you will be able to crystallize sodium bisulfate of a higher purity. There will always be a tiny equilibrium of sodium sulfate that will coprecipitate, although a large excess of acid will make this negligible.

Why do you need pure sodium bisulfate? When dissolved it acts as 1eq of sodium sulfate mixed with 1eq of sulfuric acid. Unless you need it for very precise measurements like a titration (and this is a bad standard to use, by the way) you can always just calculate the excess you need to add to complete a reaction and not bother purifying it.




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[*] posted on 27-5-2016 at 09:13


Quote: Originally posted by Praxichys  


Why do you need pure sodium bisulfate?


The sodium bisulfate will be dehydrated and then cracked to generate sulfur trioxide, although maybe the sodium sulfate will not have any effect on the process, but I'm not sure.
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[*] posted on 27-5-2016 at 14:28


Is it possible to have a condenser that is too big (not like for distilling 200 gal w/ a 1L run) but something that may serve a 30L setup used in a 4-5L run?
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[*] posted on 27-5-2016 at 19:39
Calculating moles of Acetic Acid in vinegar solution


This gets confusing to me when trying to figure out how much of something is in a solution with water.

The vinegar is 20% "200 grain" and 3785ml.
Acetic Acid 60g/mole & density of 1.049g/ml

3785ml @ 20% = 757ml
757ml @ 1.049g/ml = 794g
794g Acetic Acid @ 60g/mole = 13.234 moles

The math is correct but I'm not sure if my method is correct. Is this an accurate way of determining how many moles per gallon? I didn't weigh anything but only took the printed info for my numbers.
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[*] posted on 27-5-2016 at 19:42


Your math is correct, but most of the vinegar I've seen is 5% v/v, which works out to almost exactly 1 mol/L.



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[*] posted on 28-5-2016 at 00:17
Vacuum Gauge Noobness


Hello everyone, I have decided to buy a vacuum gauge so I can finally get into vacuum distillation. However, there are so many types of vacuum and so many units that I get hopelessly lost when trying to pick one. Attached is a photo of one that I plan to get, would this be good for most vacuum distillations?

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[*] posted on 28-5-2016 at 06:33


Well, that looks like a decent gauge, and it does cover roughly the range that you need (-.1 MPa is pretty much full vacuum). However, from what I've seen MPa is not a unit you see used that often in chemistry papers or on this site, so you might find yourself converting a lot. Getting one that covers the same range but in mmHg (torr) would be easier as far as that goes as it is used more widely. Should read 0 to -760.



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[*] posted on 31-5-2016 at 00:49


Would boiling a solution of sodium hydroxide with antimony trioxide result in a solution of sodium meta-antimonite ?

Sb2O3 + 2 NaOH ==> 2 NaSbO2 + H2O

If an excess of antimony trioxide were used then presumably a fairly pure solution of sodium meta-antimonite could be obtained?

The excess antimony trioxide would be easy to remove (filtration).

Come to think of it, is sodium meta-antimonite even stable in solution?
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[*] posted on 31-5-2016 at 05:10


Quote: Originally posted by Deathunter88  
Hello everyone, I have decided to buy a vacuum gauge so I can finally get into vacuum distillation. However, there are so many types of vacuum and so many units that I get hopelessly lost when trying to pick one. Attached is a photo of one that I plan to get, would this be good for most vacuum distillations?


I have one almost identical, the scale does not matter to me
because pressure is reported in different units by different reporters,
all you have to do is convert for recommended values then
keep notes in whatever units your gauge works.

This type of gauge is good for a rough estimate of vacuum,
as you get towards -0.1Mpa it is useless as a measure of absolute pressure,
they measure the difference between the pipe pressure and ambient atmospheric pressure, inaccurately,
but I consider it useful (especially for vacuum filtering) and good value.
I have not got a reliable low pressure (1 pa area) gauge yet ..... cost more than my pump !
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