chemists re water and methanol

[PhilC]

I'm curious about the natural tendancies of water mixed with methanol. If I leave the car sitting for a period of time, does the water and methanol mixture tend to separate (ie is it a good idea/necessary to stir)?

Thanks in advance

Phil

 

[dave6666]

Methanol and water are best shaken, not stirred...

Actually, I work at a chemical plant and I just called on of our lab chemists. At 50-50 mix it was speculated they would separate. Alcohol does not like water was the general consensus.

I would shake or stir as needed. Just slam the brakes real hard once each outing...

 

[Tom F&L GoR]

BZZZZT!!!! Incorrect answer!!

Lower molecular weight alcohol (methanol, ethanol, propanol) loves water and you will be hard pressed to separate the two. The -OH group of methanol ( CH3-OH ) makes it very water-friendly since water is H-OH.

Alcohol and water like each other so much, they will separate from gasoline. I think (I hope!!) this is what the chemists were saying. A 10% ethanol + 90% gasoline (E10 fuel) will absorb up to 10% water and then the ethanol and water will separate from the gasoline, leaving you with a stratified liquid - water+alcohol at the bottom and gasoline on top.

It is for this reason that ethanol must be transported separately to the gasoline terminals (can't go by pipeline) and consequently there is a second, parallel fuel distribution system in order to market ethanol containing fuels. While the air quality benefits of E10 are moderately exaggerated , the cost of delivery is insanely inefficient... but that's another story.

 

[dave6666]

OK Tom, I'll give you the throne for now. BUT, I'm in engineering (and not a chemist)so I just called a lab tech. Tomorrow I'll have PhD chemists by the dozens at my disposal. We'll see if I forever bow to your presence...

 

[Paul Hawker]

Alcohol loves water.

Think of all the bottled drinking alcohol (ie. Vodka) that is a blend. 40 proof is 20% alcohol.

Pure alcohol will actually steal water from the air, making it difficult to maintain pure alcohol. 195 proof is about as high as you can get.

Windshield washer fluid usually contains isopropanal alcohol. They seem to stay blended quite well.

(But I like the idea of stomping on the brakes to mix the two.)

 

[dave6666]

OK. We may have an opening for a lab tech tomorrow...

 

[Tom F&L GoR]

I'm an engineer too, and saw "dirty" gasoline, phase separation, and pumping out tanks of water contaminated fuel. You get some funny reactions between water and fuel additives, too.

The pickup in a fuel storage tank at a gas station is above the bottom floor of the tank, so that if there is water, it is supposed to sink below the pickup and customers only receive gasoline. Periodically the station is supposed to pump out the water bottoms. If something happens to where the fuel becomes saturated, the 3% water bottom suddenly becomes 6% water+alcohol and the station pumps that mix into cars.... arrgh.

That probably doesn't happen anymore, since the use of alcohol blends has "dried up" all the tanks, but when gasohol first started, it was a distribution system problem.

 

[PhilC]

Thanks for the replies. One less thing for me to concern myself with. Have a great day.

Phil

 

[PAvenomRT/10]

When was the last time you saw your bottle of wine, liquor or other alcoholic beverage separate into 2 distinct layers? As Tom said, lower molecular weight alcohols like methanol and ethanol are readily miscible with water and do not separate out. No need to shake or stir.
Pavenom RT/10

 

[dave6666]

OK gentlemen, got to talk to some REAL chemists today, and the consensus was unanimous. Methanol and water do stay mixed.

BTW, we have an opening for a lab tech...

 

[dave6666]

When was the last time you saw your bottle of wine, liquor or other alcoholic beverage separate into 2 distinct layers?

Whatdaya mean? Every time I get faced at a bar I deal with separation.

 

[PAvenomRT/10]

BTW,
I am a real chemist.
PAvenom RT/10