Shot of Ethanol: Is 100% Possible?

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Discussion Overview

The discussion revolves around the possibility of obtaining 100% ethanol, addressing both theoretical and practical aspects of ethanol purity, particularly in the context of laboratory and medical applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that 100% ethanol is theoretically possible but difficult to achieve due to ethanol's affinity for water, which leads to contamination from the air.
  • Others mention that while 100% ethanol can be produced, it typically requires specific methods such as using benzene to remove water or employing chemical reactions.
  • A participant notes that medical-grade ethanol is available as USP grade, which is claimed to be 100% pure, but questions arise about the necessity of such purity compared to 95% ethanol for most applications.
  • Some participants discuss the practical challenges of achieving 100% ethanol, including environmental factors and the costs associated with obtaining it.
  • There are mentions of alternative methods to remove water from ethanol, including the use of calcium oxide and hydrides like LiAlH4.
  • One participant raises a question about the role of hydrogen bonding in limiting the concentration of ethanol.
  • Several participants highlight the existence of azeotropes and the potential for breaking them through pressure modification or molecular sieves.

Areas of Agreement / Disagreement

Participants express a range of views on the possibility of achieving 100% ethanol, with some asserting it is theoretically possible while others emphasize practical limitations. There is no consensus on the necessity or practicality of 100% ethanol for various applications.

Contextual Notes

Limitations include the dependence on specific methods for achieving high purity, the role of environmental factors in contamination, and the unresolved nature of the discussion regarding the necessity of 100% ethanol in medical contexts.

Snap
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100% ethanol ??

Hi All

First off, this is one cool site, lots of neat info.

Now for my question. I have to clear an argument with one of my students. I work in an emergency department and I was teaching them the role of different alcohol poisonings and how we treat the overdoses. Ever so long ago (15yrs) I was told in bio-chem that 100% ethanol was not possible due to the nature of the molecule. This student works in a lab and said that there was 100% ethanol available.

SO... is it possible? or is it really 98%'ish and for the sake of argument labs label it as 100 %

Thanks all
Snap
 
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I haven't heard that.

But ususally, ethanol is denatured, meaning a small amount of another solvent is purposefully added to it.

A lab I used to work at used un-denatured (= natured?) ethanol, but they had to register with the local Alcohol Control Board. As I understood, that was "pure" ethanol, but I didn't work with it directly so I don't know the details. I do remember that the bottles wouldn't last long, not because we were imbibing, but because it would get contaminated easily by water.
 
100% ethanol is possible, just not from typical distillation. Don't ask me how I know because I will just plead the 5th. :cool:
Pure ethanol has a great affinity for water and will absorb it from the air until it is only about 96% pure.
 
Thanks all

Since I only have dial-up at home I could only find out that there is 99.99% pure due to the fact they have to use benzene to remove the 4% water and then remove the benzene. Perhaps a better question is "medical grade ethanol" 100% ? and why would you bother if you could get 96% since I am sure it is very expensive to get that extra 4 % when we mix the ethanol in a saline solution to get 10% solution


Thanks
 
Snap said:
Thanks all

Since I only have dial-up at home I could only find out that there is 99.99% pure due to the fact they have to use benzene to remove the 4% water and then remove the benzene. Perhaps a better question is "medical grade ethanol" 100% ? and why would you bother if you could get 96% since I am sure it is very expensive to get that extra 4 % when we mix the ethanol in a saline solution to get 10% solution


Thanks

Yes, 100% medical grade ethanol is sold as USP grade.

I use this to recrystallize deliquescent materials. The 190 proof (95%) grade will cause these materials to 'oil out' instead of recrystallizing.
 
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Yes, for some applications, we need 100% ethanol as well, as water in it will interfere with what we are doing, and yes, it is a LOT more expensive and requires a license to purchase. For most other uses, we use histology grade, which is 95% ethanol and 5% isopropanol and methanol (I don't think how much of each is specified, but if it mattered, I'm sure it could be found out). For medical applications, I don't know of any reason you'd ever need more than 95% ethanol, as long as there was no methanol contamination, and usually 70% is adequate for all the usual purposes.
 
does that considering the hyrogen bonding that can Alcohol form between molecules itself?..if so..certainly alcohol can not ever be in conc. of 100%.
 
in theoretical degree, it is possible.
by repeating the fractional distillation of a solution of ethanol and water, you will finally get about 96% of ethanol solution in terms of purity. Then, using CaO to help you remove the remained water.

but in fact, it does not exsit. by both environmental factors and practical factor.
 
mysqlpress said:
in theoretical degree, it is possible.
by repeating the fractional distillation of a solution of ethanol and water, you will finally get about 96% of ethanol solution in terms of purity. Then, using CaO to help you remove the remained water.

but in fact, it does not exsit. by both environmental factors and practical factor.
It doesn't exist? What do you mean? You cannot certainly make 100% ethanol by distillation, but you can synthesize it in many ways.
If you use sodium ethoxide, you would need to *add* water, to make ethanol! :

Na(OCH2CH3) + H2O --> NaOH + CH3CH2OH

This reaction is also an example of how you can eliminate water from ethanol.
 
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  • #10
To eliminate water completely from ethanol an example is to use an hydride, as LiALH4:

LiAlH4 + 4H2O --> LiOH + Al(OH)3 + 4H2
 

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