Gas, water & alcohol

[Iamme]

If your car engine sputters it may be due to 'bad' gas. During this time of year supposedly, gasoline can condense down below ground in the underground gas tanks (so I have heard). People sometimes get gas contaminated by water.

You are supposed to pour in a bottle of this alcohol based water based drying agent, to get you fixed up. A lot of people buy the stuff and dump it in their tank, whether they need to or not...just to be on the safe side...they think.

Hmmm. I have a farm tractor. It has one of those clear sediment traps in the fuel line. It was all full of water. I first dumped out the glass bowl (obviously). Then I removed the gas as good as I could, out of the tank, and....well, I WAS going to dump in some of that alcohol based drying agent, but decided to conduct an experiment first. (I am good for doing this.)

I took an empty glass jar and put gas in it. Then I put water in it. Then, I put a generous amount of the alchol in it. And I shook it up and let it settle out. What I expected to find is the alcohol and water combined/maybe the gas as well. Instead, this is what I got, starting from the bottom up: A layer of water...a layer of alcohol...a layer of gas.

Hmmmmmm. What the heck good does that stuff do, ANYway?

[Mr. Skinny]

I think you meant to say that water vapor can condense in the underground storage tanks.

Did you run your experiment with one of the commercial products, or did you just use straight alcohol? The commercial product may have an ingredient that puts the water/alcohol into dispersion somehow so that it gradually gets passed through the engine.

If all the water settled to the bottom of the gas tank (as in your experiment) it seems like a recipe for disaster. Surely the commercial products wouldn't do that, would they?

[_Q_]

You might have a look at this message from Bruce Hamilton (http://yarchive.net/chem/gasoline_dewater.html) regarding water tolerance in gasoline. He even describes a procedure one might use to test the water tolerance of their own gasoline. Since no quantities were specified, I can't know, but it might be the case that the "water load" in lamme's experiment is simply beyond what can be handled with an acceptable quantity of alcohol. (That lamme observes three layers baffles me.)

The message above includes a portion extracted from his Gasoline faq (http://www.faqs.org/faqs/by-newsgroup/rec/rec.autos.tech.html) (dig around some, and you can find some sites that post the content of this faq all in one place in HTML format).


_Q_

[wollery]

My chemistry may be a bit rusty, but I'm pretty darn sure that all alcohols are extremely soluble in water, so how could you possibly have got a layer of alcohol on top of a layer of water?

[wayrad]

Originally posted by wollery
My chemistry may be a bit rusty, but I'm pretty darn sure that all alcohols are extremely soluble in water, so how could you possibly have got a layer of alcohol on top of a layer of water? If it was salty water, maybe he made Urschleim. :D

edited to add: a hilarious account of the discovery of the "primordial ooze", Bathybius haeckelii, can be found at
http://www.american-buddha.com/great.deep.htm

[patnray]

Having grown up in a colder environment, I am familiar with this subject. In a cold climate water vapor may condense in your own gas tank. The water will not mix with the gasoline, and being denser, it will settle to the bottom of the tank. IF enough condenses, and IF it gets sucked into the fuel line, it can cause sputtering of the engine. The products sold to relieve the problem are basically methyl alcohol. One side of the molecule is non-polar and mixes well with gasoline. The OH side of the molecule is polar and mixes with water. So it helps to disperse small quantities of water within the gasoline and prevent the sputtering. It only helps if there is a very small quantity of water. The problem is not as wide spread as people believe - there are other reasons for sputtering, especially when the engine is very cold. And you have to keep your tank near empty for long periods to get a significant amount of condensation. But "Dry Gas" is cheap, heavily marketed, and widely available. I knew people who used it regularly during the winter months to "prevent" problems....

[Iamme]

Mr. Skinny---What you said, and what i said, about the condensation are one in the same.

It was a commercial gas line dryng agent/anti-freeze, that is one of the well known brands.

[Iamme]

_Q_ & wollery---Yes, I indeed had 3 seperate layers. That's why I came to the conclusion that such a product claiming it dries the water out of gas is baloney. I had layers in the empty mayonaise jar of about 1/2 inch of each layer. And I too have heard that the alcohol dries out only small amounts of water. But...to even dry out small amounts...why would I believe this would happen based on my observation of it not mixing?

If drying is caused by some other principle...what would that principle be, when the water is trapped at the bottom? IF the water were say to evaporate...it would have to evaporate through the alcohol and then the gas. Then, even if it did...where would the vapors go? Many fuel systems today are 'closed', aren't they?...with that fuel vapor recovery canister?

[Iamme]

patnray---Informative. Thanx. :)

[_Q_]

Originally posted by wollery
My chemistry may be a bit rusty, but I'm pretty darn sure that all alcohols are extremely soluble in water, so how could you possibly have got a layer of alcohol on top of a layer of water?
The small alcohols (methanol, ethanol, propanol) are extremely soluble in water. Solubility in water decreases dramatically as one moves to larger (more carbon chain) alcohols. For a straight carbon chain, n-butanol (just one carbon longer than propanol) is only soluble to the tune of 8.3 g per 100 mL of water at room temperature. (The branched t-butanol is also very soluble in water.)

So yes, one can have a layer of alcohol on top of a layer of water.


_Q_

[_Q_]

Originally posted by Iamme
_Q_ & wollery---Yes, I indeed had 3 seperate layers. That's why I came to the conclusion that such a product claiming it dries the water out of gas is baloney. I had layers in the empty mayonaise jar of about 1/2 inch of each layer. And I too have heard that the alcohol dries out only small amounts of water. But...to even dry out small amounts...why would I believe this would happen based on my observation of it not mixing?

If drying is caused by some other principle...what would that principle be, when the water is trapped at the bottom? IF the water were say to evaporate...it would have to evaporate through the alcohol and then the gas. Then, even if it did...where would the vapors go? Many fuel systems today are 'closed', aren't they?...with that fuel vapor recovery canister?
lamme,

Part of the problem here may be that you're trying to draw conclusions from an experiment in which the proportions of materials used are very far away from normal reality. Look at the message to which I linked in an earlier message regarding "water tolerance" of gasoline, that is, how much water it can tolerate before a second phase forms. Look at how small the numbers are - much, much smaller proportions of water than you were using.

It might help if we knew what was in the additive you were using. It might be the case that it's completely soluble in gasoline when mixed in the normal proportions, but not in the proportions used in your experiment (way more additive than usual for a given amount of gasoline). It also might be not completely soluble in water. This would be consistent with your observation of three layers. Keep in mind that your layers don't necessarily have to be pure gasoline, additive, and water - it could be that the "gasoline" layer was gasoline, with as much additive as could be dissolved in it, plus as much water as that much additive will allow it to "hold".

If you want to test this, then try some experiments to check the solubility of the additive in, respectively, gasoline and water.

I'll also point out again that the message to which I linked earlier even suggests a procedure for checking the water tolerance of your own gasoline, both with and without the use of "water removing" additives. You'd be checking to see when no more water can be dissolved in a particular gasoline/additive mixture, ranging from untreated gasoline to the "normal" mix of gasoline and additive. Note also that the water tolerance can have much to do with the composition of the gasoline itself.


_Q_

[Iamme]

_Q_---Interesting. Maybe you're right. So...Iamme will now try to simulate the exact proportions of that which one could expect in a real situation (within reasonable parameters). I can't say when I'll do this...but I *will* do it. You can bet on it.

[Iamme]

I was just at the convenience store, and I walked past a display of "Heet" (dry gas). They had two kinds. One was the regular strength which contained methyl alcohol. Their other version absorbs 5 times more water. That one is isopropyl alcohol. That is the one that I used in my experiment!...where I was shocked to simply find the gas, alcohol and water in stratad layers.

I'll conduct another experiment with lesser water in the near future and will post about it.