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Offline Shingoshi

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« on: 28/08/2007 06:17:07 »
This question is for creating a very low subzero refrigerant.
1. Is it safe to mix acetone, methanol and hydrogen peroxide together?
2. Would it be safe to mix them with trichlor?
3. Would this form an azeotropic compound suitable as a refrigerant?
4. What would the freezing points of these solutions be?

Shingoshi

Please note: newbielink:http://www.virtualsciencefair.org/2007/park7l2/conclusion.html [nonactive]
Concerning the stability of Hydrogen Peroxide in Ethanol.

Quote
The mixture between ethanol and hydrogen peroxide is safe and stable as hydrogen peroxide is fully miscible with ethanol which is able to dissolve both polar and nonpolar substances due to its polar hydroxyl group and nonpolar hydrocarbon structure.
« Last Edit: 08/09/2007 13:20:54 by Shingoshi »


 

Offline eric l

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« Reply #1 on: 28/08/2007 09:50:00 »
I would not recommend mixing hydrogen peroxide (concentrated I suppose) with any organic solvent.  I don't have the data here, but you exoect more details (links) within the next hours.
 

Offline eric l

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« Reply #2 on: 28/08/2007 10:07:44 »
You can find a good page of information on azeotropic mixtures in Wikipedia (http://en.wikipedia.org/wiki/Azeotrope_(data))
If you need more, there's always Wiley's "Azeotropic Data" (about 2000 pages, priced 705 ) (http://eu.wiley.com/WileyCDA/WileyTitle/productCd-3527308334.html) but as far as I remember it does not give melting/freezing points.
As for the safety hazards for hydrogen peroxide :
(and many more)
 

Offline Bored chemist

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« Reply #3 on: 28/08/2007 11:28:48 »
Are we talking about azeotropes here or eutectics?
Anyway, don't use hydrogen peroxide for anything unless you have to.
 

Offline Shingoshi

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« Reply #4 on: 28/08/2007 11:39:19 »
I get the point about H2O2. I won't be using it. More trouble than it's worth. And maybe wouldn't even give the results I wanted anyway.  I was simply looking for a fluid to replace water to get a lower freezing point. I want a liquid which can't freeze in my cooling system, while still being able to flow at -100C. I've noticed that Formaldehyde freezes at -117C. But I don't know how much of that is lost in the presence of water, at what ratio.

I need an azeotropic fluid, because part of my system will be vaporizing this fluid to create a low pressure area in which the liquid being pumped through an ejector/eductor will undergo rapid depressurization to acquire my refrigeration effect due to phase-change.

I had already looked at Wikipedia and the date there for azeotropes. Just read the data on eutectics, not thoroughly though. It seems that applies to metals. I am looking for a fluid with the lowest melting point possible, which doesn't itself require cryogenic storage.

Shingoshi
« Last Edit: 28/08/2007 12:19:19 by Shingoshi »
 

Offline lightarrow

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« Reply #5 on: 28/08/2007 12:31:34 »
This question is for creating a very low subzero refrigerant.
1. Is it safe to mix acetone, methanol and hydrogen peroxide together?
2. Would it be safe to mix them with trichlor?
3. Would this form an azeotropic compound suitable as a refrigerant?
4. What would the freezing points of these solutions be?

Shingoshi
Why do you want to mix these compounds? I strongly advise you not to do it. From what you write you are NOT an expert chemist.
What do you mean with trichlor?
I think you are not conscious of what you want to do. I advise you again: Many people died because they didn't know Exactly what they were doing.
 

Offline Shingoshi

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« Reply #6 on: 28/08/2007 12:58:36 »
This question is for creating a very low subzero refrigerant.
1. Is it safe to mix acetone, methanol and hydrogen peroxide together?
2. Would it be safe to mix them with trichlor?
3. Would this form an azeotropic compound suitable as a refrigerant?
4. What would the freezing points of these solutions be?

Shingoshi
Why do you want to mix these compounds? I strongly advise you not to do it. From what you write you are NOT an expert chemist.
What do you mean with trichlor?
I think you are not conscious of what you want to do. I advise you again: Many people died
because they didn't know Exactly what they were doing.

If I were inclined to doing this without being properly informed, I wouldn't have bothered writing my questions here!

I already said I won't be using H2O2. Should I have written that in capital letters?  Acetone-Methanol-Water is already used for this. I just wanted lower temperatures than could be acquired with water.
 

Offline eric l

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« Reply #7 on: 28/08/2007 13:31:57 »
My first reaction was quick and incomplete (which is why I promissed more within the next hours) because I feared you were in for dangerous exoeriments.  Bored Cemists abd Lightarrow have confirmed that, And I think we are all glad that you no longer persue that H2O2-course. No need to blame anyone for repeating a warning.

"Azeotropic" has everything to do with boiling point, few tables on azeotropic mixtures give information about freezing point.  And in most cases, you will find data (boiling points) for atmospheric pressure, while you state you want to create low pressure zones.  (That 3-volume book I mentioned does give boiling points at other pressures).

I'm affraid you're in for a lot of testing.  Keep it safe and check material safety data sheets for every ingredient before mixing things.

Lots of luck. 
 

Offline Bored chemist

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« Reply #8 on: 28/08/2007 14:25:01 »
Formaldehyde is a gas and unpleasant to work with. Forget it.
Methanol, used in some anti freeze will get down to -98 C. There's an acetone / methanol azeotrope which boils at about 55C. I think it will still be liquid at -100 C.
Obviously, it's somewhat toxic, flammable and attacks plastics.
 

Offline lightarrow

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« Reply #9 on: 28/08/2007 19:58:52 »
I already said I won't be using H2O2. Should I have written that in capital letters?
Sorry, I didn't see your second post.
Quote
  Acetone-Methanol-Water is already used for this. I just wanted lower temperatures than could be acquired with water.
I give you some substances melting and boiling points in C:

Ethanol                -114      78.3
Ethyl ether           -116.3    34.6
Toluene                -95.0   110.6
CS2                     -111.6    46.2
Tetrahydrofuran    -108.5    66.4

I wouldn't advise the last two, for their toxycity and danger of fire (ethyl ether too but less dangerous).
Ethanol and Toluene forms an azeotrope: 68% Ethanol  and 32%Toluene.  Boiling point: 76.7C. I don't know the melting point of this mix; from the melting points of the pure substances, it could seem less than -100C, but, who knows.
« Last Edit: 28/08/2007 20:14:17 by lightarrow »
 

Offline Shingoshi

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« Reply #10 on: 28/08/2007 21:13:36 »
Let's face it! There are few if any compounds which remain in liquid form at room temperature, that won't freeze before -90C, which aren't either toxic, flammable or both. Ammonia, which has a long history as a refrigerant, is extremely toxic, as are many of the compounds derived from it. So repeating warnings about toxicity and flammability are without merit. It is virtually impossible to engage this topic without them.

So, let me highlight my two primary considerations.

1. Remains a liquid at room temperature.
2. Doesn't freeze above -90C.

Additionally. Should not be a banned or restricted substance, but readily available to consumers.

Flammability aside. I would not want to work with substances which are by nature explosive. Flammability (by ignition) can typically be managed. Explosivity (by detonation) typically is not. This system will be thoroughly contained, as is any other phase-change refrigeration system. The nature of it being closed reduces risk of flammability, but increases the risk of explosion.

The odor of Formaldehyde is irrelevant. Though I think at this point I am inclined to use ammonia instead of water to be mixed with methanol/acetone. Since ammonia is not pure, but has a high portion of water in it (in commercial form) anyway. Although, just out of curiosity, how would Formaldehyde behave with acetone/methanol? Does anyone have any data on the freezing point of that solution? Formaldehyde looks very nice at -117C!

Shingoshi
 

Offline lightarrow

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« Reply #11 on: 28/08/2007 23:51:50 »
So, let me highlight my two primary considerations.

1. Remains a liquid at room temperature.
2. Doesn't freeze above -90C.

Additionally. Should not be a banned or restricted substance, but readily available to consumers.
Ethanol is banned in your country?
 

Offline Shingoshi

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« Reply #12 on: 29/08/2007 04:29:01 »
So, let me highlight my two primary considerations.

1. Remains a liquid at room temperature.
2. Doesn't freeze above -90C.

Additionally. Should not be a banned or restricted substance, but readily available to consumers.
Ethanol is banned in your country?

I need to look into it. I was under the impression that it is. I may be wrong. But I know that whatever form it comes in, it is denatured. They don't want anyone drinking it!

Shingoshi
 

Offline eric l

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« Reply #13 on: 29/08/2007 08:34:10 »


The odor of Formaldehyde is irrelevant.


Not at all :  the concentration at which you start to smell it is above the MAC (maximum admissible concentration for working spaces)  see also http://physchem.ox.ac.uk/MSDS/FO/formaldehyde.html code IHL/TCLO (inhalation - lowest published toxic concentration)
This MAC values have been revised (read lowered) about 10 years ago, after new studies; we used to consider formaldehyde as relatively safe, because we would smell way before the toxic concentration was reached.  With the new standard, we needed sensors all over the place
 

Offline Shingoshi

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« Reply #14 on: 29/08/2007 09:07:54 »


The odor of Formaldehyde is irrelevant.


Not at all :  the concentration at which you start to smell it is above the MAC (maximum admissible concentration for working spaces)  see also newbielink:http://physchem.ox.ac.uk/MSDS/FO/formaldehyde.html [nonactive] code IHL/TCLO (inhalation - lowest published toxic concentration)
This MAC values have been revised (read lowered) about 10 years ago, after new studies; we used to consider formaldehyde as relatively safe, because we would smell way before the toxic concentration was reached.  With the new standard, we needed sensors all over the place

Thank you. But you missed my point. Basically I was saying I should never be in a position to smell it. My only concern (exposure) would be when I am installing the system, not during it's operation. But I appreciate your comment, and it is well taken.

Quote
Hey lightarrow, Thanks! You guys should check this out. I only found it because of our discussion. Here's the link to something interesting. Seems like an alternative to Peltiers for computer cooling systems, which is what this will ultimately be used for.
newbielink:http://www.che.cemr.wvu.edu/publications/projects/prod_design/magnetic_refrigerator.pdf [nonactive]
Forget the above. I should have read further!

Shingoshi
« Last Edit: 29/08/2007 09:59:26 by Shingoshi »
 

Offline Bored chemist

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« Reply #15 on: 29/08/2007 20:22:34 »
Denatured alcohol will probably work fine.

"Thank you. But you missed my point. Basically I was saying I should never be in a position to smell it. My only concern (exposure) would be when I am installing the system, not during it's operation. But I appreciate your comment, and it is well taken."
And when things go wrong, then what? It never makes sense to chose a toxic or otherwise hazardous chemical where a relatively safe one will do.

Formaldehyde will react with acetone or methanol. Anyway, did you not read what I said earlier- it's a gas so it doesn't meet the criteria you asked for. It boils at minus twenty or so. Oh, and it's a suspect carcinogen too.
Really forget it.

Methanol with a little water in will not freeze at -100. It's flammable and toxic but so (as you say) are the others. This would be my second choice if I couldn't get methylated spirit or some such.

CS2 is very unpleasant to work with, unless you like compounds that are neurotoxic, almost spontaneously inflammable and that smell like a particularly rank fart.
THF isn't very toxic but it forms explosive peroxides on exposure to air so I'd not use it if I were you.
Ammonia is corrosive as hell, particularly if it has water in it.
 

Offline Shingoshi

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« Reply #16 on: 06/09/2007 19:00:23 »
Hey guys,
Sorry for continuing this. But I have a crazy question. Since water is capable of absorbing some gases, I am wondering if and/or to what extent ethanol can absorb propane? I have looked using Google, but haven't found any direct information.

Thanks,
Shingoshi
 

Offline Bored chemist

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« Reply #17 on: 06/09/2007 20:29:33 »
I don't know about propane but I know you can dissolve enough butane in ethanol to get a mixture that's fizzy when it warms up to room temperature. I don't recomend this drink, it tasted funny and was too cold to enjoy.

If you can find any data on the solubillity at some pressure then you can calculate the solubillity at another pressure. To a fairly good aproximation, the solubillity is proportional to the pressure. I think what you need to look up are "Henry's law constants"

I also feel I ought to point out that there are easier ways to blow yourself into the hereafter with less risk of taking innocent bystanders with you.
 

Offline Shingoshi

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« Reply #18 on: 07/09/2007 01:11:26 »
Why would anyone want to drink butane! You have got to be kidding.

I was sure what other gas I could mix with ethanol, that wouldn't immediately evaporate, defeating my attempt to create a mixture. This all goes back to azeotropes. I was wondering if I got enough propane into the ethanol, if I could drop the freezing point of the ethanol to be closer to that of the propane. In my searching google, I came across a patent application for some sort of medical application using a mixture of water, ethanol and propane as a disinfectant. But the portion of propane in the mixture was very low.

I was wanting to keep using a liquid for my design for the simplicity of maintenance. Thanks to all of your suggestions, ethanol seems the best. But then propane dissolved in ethanol didn't seem to be that unmanageable. Everything that I am doing will be in an enclosed system, like that of a refrigerator. Except that I will be using hoses that are overspec. So I don't know the degree of increased risk by doing this.
 

Offline Shingoshi

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« Reply #19 on: 07/09/2007 02:33:09 »
Hey guys,
This has got to be funny. I did a Google search for "freezing point table azeotropic compounds" (without the quotes), and came up with this discussion as the first link. How's that for affecting the world we live in!

http://www.thenakedscientists.com/forum/index.php?topic=9728.msg119838

Congrats to all!
 

Offline Shingoshi

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« Reply #20 on: 10/12/2007 05:29:01 »
Which if any of the following mixtures are azeotropes?
1. Ethanol and Mineral Oil
2. Ethanol and Turpentine (@-50*C freezing point)
3. Mineral Oil and Turpentine
4. Ethanol, Mineral Oil and Turpentine

Shingoshi
2007.Dec.09 Sun, 09:37 --800 (PST)
 

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