22 votes
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Un-denaturing industrial alcohol

(I'm no chemist, but here's my take on it) Let's see: I’m an alcoholic, and I really hate having to dole out large amounts of cash to purchase your usual "drinking"-ethanol. So I get this amazing ...
paracetamol's user avatar
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19 votes

Enrichment of D2O

Fractional distillation can work, but the separation per round of distillation is very low so you would need a very large multi stage process to achieve significant separation. Nobody uses direct ...
matt_black's user avatar
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14 votes
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How to increase the concentration of HCl

Add Calcium Chloride to destroy the azeotrope. Then distill and capture the vapor phase. See the second method "Extractive Distillation" here: http://www.jacobs.com/uploadedFiles/wwwjacobscom/...
DavePhD's user avatar
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11 votes

Un-denaturing industrial alcohol

In Soviet Russia, where alcoholism was widespread and homebrewing illegal, undenaturing alcohol was a pretty common thing - a part of national culture, in a way - along with such practices as: ...
Ivan Neretin's user avatar
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11 votes

Un-denaturing industrial alcohol

The reason criminals don't undenture alcohol is probably because it's cheap and easy to make your own alcohol at home. Plus it's legal in the US (click on G1) and most other English-speaking ...
Jason's user avatar
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11 votes

Does distilled water still have ions in it? Does deionized water lack ions, but still have other "stuff" in it?

Any water contains ions due water self-ionization and usually extra ones due dissolved aerial carbon dioxide ( being a weak acid ). Distilled water can still contain volatiles(like chloroform from ...
Poutnik's user avatar
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10 votes

How to increase the concentration of HCl

Irrespective of the potential hazards to an inexperienced chemist attempting distillation of hydrochloric acid, especially absence of adequate safety measures such as a fume hood, in this case, ...
iad22agp's user avatar
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8 votes

Do light and heavy water form an azeotrope?

This is a good question, but no, there is no azeotrope in any isotopic mixture, as an azeotrope requires non-ideal mixing of two components to form a minimum or maximum critical point on the plot of ...
A.K.'s user avatar
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8 votes

Enrichment of D2O

For a comparison of different methods, including distillation and the Girdler processes, have a look at Heavy Water: A Manufacturers’ Guide for the Hydrogen Century In this 14 pages document a survey ...
Raoul Kessels's user avatar
8 votes

Alcohol (ethanol) distillation: mystery congener

People turn apple cider all the way to apple cider vinegar, so during the process, there will be a time when the amount and ratio of ethanol and acetic acid are optimally balanced for making ethyl ...
James Gaidis's user avatar
7 votes

Glass joint stuck in flask

You have multiple options. All of them assume that the distillation setup is empty, at ambient pressure. Of course, like mentioned in the comment by @Waylander, put a little of (silicon) grease on ...
Buttonwood's user avatar
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7 votes
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Why does the ethanol-water mixture not burn during fractional distillation?

According to Wikipedia, ethanol flash point is $\pu{55 ^\circ F} = \pu{12 ^\circ C}$. Auto-ignition temperature is $\pu{793 ^\circ F} = \pu{423 ^\circ C}$. It means that ethanol vapor cannot be put on ...
Maurice's user avatar
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7 votes
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Stratification of gasses by mass

These questions are addressed well in this 2009 paper by Giovanni Badino: The Legend of Carbon Dioxide Heaviness. Gravitational stratification does occur, but it is a result of the fact that change in ...
feetwet's user avatar
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7 votes
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NMR and dienes to isolate certain isotopes?

There are at least two glaring problems: Look at the energy scales on which NMR operates (for example, take the resonance frequency $\nu$ and calculate the associated energy $h\nu$)... and compare it ...
orthocresol's user avatar
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6 votes

Un-denaturing industrial alcohol

As @matt_black and @Aaron Abraham suggested, cleaning the denaturated ethanol is difficult and expensive. You don't know, what chemicals other than ethanol and methanol are in the solution and in what ...
Crowley's user avatar
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6 votes
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Deuterium depleted water through fractional distilation

Relying on the difference in vapor pressures of $\ce{HDO}$ and $\ce{H2O}$ is equivalent on relying on the equilibration of $\ce{HDO(g) + H2O(l) <=> H2O(g) + HDO(l)}$ The fractionation factor $...
Curt F.'s user avatar
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6 votes

Why we don't we save water by boiling the contaminated water to get the pure steam?

Boiling a water mixture doesn't always produce pure water. Boiling a solution of salt and water (or evaporating the water) will separate the salt from the water, but those are compounds with very ...
Van's user avatar
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6 votes
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How can I read an Anschütz/Bennert manometer and how can I make sense of it?

All operations should be gentle: open the valve to the system evacuated if the vacuum applied is good enough, the level of mercury in the right hand (open) leg rises, the level in the left hand (...
Buttonwood's user avatar
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5 votes

To heat or not to heat; distillation?

You obviously already have a general idea of what is going on in a distillation, so I will spare you the picture and everything. Your question can be broken into two parts: Do I need heat for ...
Jan's user avatar
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5 votes

Do light and heavy water form an azeotrope?

Distillation alone has been used on an industrial scale to produce heavy water, but it requires a multi-stage process and uses a lot of energy due to the small difference in boiling points. That would ...
iad22agp's user avatar
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5 votes

Glass joint stuck in flask

Silicon grease is the one we used normally. But, your post indicates that grease hasn't worked for you. Any adhesive tape wouldn't work because it will increase the risk of leaking (specially when you ...
Mathew Mahindaratne's user avatar
5 votes

Does distilled water still have ions in it? Does deionized water lack ions, but still have other "stuff" in it?

Distilled water will always contain some ions no matter how pure There is a simple sense in which even the purest distilled or "deionised" water will always have ions in it. Water self ...
matt_black's user avatar
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5 votes

Could fluorinated gases be removed from the atmosphere?

Short answer? No. All gases are prefectly mixed in the atmosphere, except if you can catch them directly an the source. That's just thermodynamics. It's already an imo crazy idea trying to remove CO2 ...
Karl's user avatar
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5 votes

"Cleaning" of HNO3 solution using distillation

What is a piece of cake for $\pu{1 L}$ might become a nightmare for $\ce{10 000 L}$. So think twice… $\ce{HNO3}$ forms an azeotrope with maximum of boiling point $\pu{120.5 ^\circ C}$ at $w(\ce{HNO3}) ...
Poutnik's user avatar
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5 votes

Distillation thermometer position

The temperature drop is obviously due high heat loses on the way up. It is usually minimized by proper thermal isolation of the upward path. The favorite way in student labs is wrapping the glass by $\...
Poutnik's user avatar
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4 votes

Distilling small volume

In order to both achieve sufficient separation and minimize loss during fractional distillation, you want a large inner column surface for optimal contact of the vapour phase (upstream) and the ...
Klaus-Dieter Warzecha's user avatar
4 votes
Accepted

Can the enrichment of Uranium be done via manipulating the boiling/melting point difference between differing isotopes of the same element?

Of course isotopes may be separated by distillation, but it's useful, AFAIR, only for hydrogen isotopes. For uranium, gas centrifuge is proven much cheaper, to some orders of magnitude: https://ru....
sa7's user avatar
  • 520
4 votes

Alcohol (ethanol) distillation: mystery congener

Like 'Jamie Gaidis' I was convinced at least some of the suspected $\ce{EtAc}$ is formed during the distillation step but presently I no longer believe that. Instead I believe that compound is formed ...
Gert's user avatar
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4 votes

Does distilled water still have ions in it? Does deionized water lack ions, but still have other "stuff" in it?

Distilled water main impurity is due to the dissolution of atmospheric $\ce{CO2}$ which produces some acidity due to the reaction $\ce{CO2 + H2O -> H3O+ + HCO3^-}$. Usually it is sufficient to ...
Maurice's user avatar
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4 votes

NMR and dienes to isolate certain isotopes?

Look up the difference of the isotopic masses between hydrogen and deuterium (a factor of about 2),* and the two isotopes of uranium (difference here $\approx1.5\%$), e.g. in NIST's table of atomic ...
Buttonwood's user avatar
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