Chemistry Question

C

C-Hawk

New member
Question is as follows....

I filled a glass with 40% ethanol solution and left it open on the lab bench. When I came back next morning to the lab, I found that the ethanol concentration in the glass was still 40%. How is this?
 
I guess the first question is what was the other 60%? You didn't say that the level was the same, so I would deduce that the evaporation rate of the other 60% was the same, so that the concentration was the same, but volumn was less??
 
What is the container? ex a glass or bowl.
Surface area is one factor. A bowl containing liquid will have a larger surface area than the liquid in a glass. Temperature is another factor. Is it stored at ambient temperature?

I believe the alcohol solution will be close to the vapor pressure of water and should evaporate in the same manner as water. So add a control.
Using the same but a different container, add the same volume of water. Mark the outside level of the containers or use a straw and record the depth. Record the temperature, date and time then check the container and record the variables at defined times. Make a table. Make a graph! and repost your results.

I tried this experiment several times. The glass of alcohol was always had less volume than the glass of water with no alcohol.

What happened?

I used bourbon and water in container A and tap water in container B. After 5 minutes, I got bored and drank container A. This is why I got a blue ribbon in science fairs.

I suppose I can think of a P-chem, too

just having fun !
 
Several years ago I did an experiment to determine the percentage of alcohol in gas.... I needed graduated cylinders and all that neat junk to do... (I actually had them those days) but for the life of me today I can't remember the process.... (probably diden't work)

I do have a neat water test kit from MDR called a Water Probe Indicator.... all you do is brush this liquid onto a stick and put the stick in the fuel tank....the liquid will turn from yellow to bright red if there is any water in the fuel....(works in diesel and heating oil too)

Joel
SEA3PO
 
Roger the evaporation of alcohol is also directly related to the heat of the liquid that the alcohol is suspended in....and the type of alcohol you are using.....

Methyl Alcohol boils off at 149 degrees F.
Ethyl Alcohol boils off at 173 degrees F.
Isopropyl Alcohol boils off at 180 degrees F.

Just make sure yer still never gets above 212 degrees and you will be just fine.

Joel
SEA3PO
 
oldgrowth":2tcl0l4k said:
Brent – looks like you know how to perform a scientific test.
________
Dave dlt.gif
Click to expand...

Excellent reproducibility
Other factors to consider
Having too much fun and pass out or run out of reagents.
 
SEA3PO":18zzwrfq said:
Several years ago I did an experiment to determine the percentage of alcohol in gas.... I needed graduated cylinders and all that neat junk to do... (I actually had them those days) but for the life of me today I can't remember the process.... (probably diden't work)

I do have a neat water test kit from MDR called a Water Probe Indicator.... all you do is brush this liquid onto a stick and put the stick in the fuel tank....the liquid will turn from yellow to bright red if there is any water in the fuel....(works in diesel and heating oil too)

Joel
SEA3PO
Click to expand...

Is WPI accurate? What are the limits? I expect fuel should have some water considering the pathway from production to consumer.
 
Fishtales":acel87xo said:
I filled a glass with 40% ethanol solution and left it open on the lab bench. When I came back next morning to the lab, I found that the ethanol concentration in the glass was still 40%. How is this?
Click to expand...
There is a low-boiling azeotrope of water and ethanol at 5%water/95% ethanol, but that does not apply here.

I guess my first question is how did you ascertain that the % ethanol had remained constant?
 
Some of ya are on the right trail :cocktail

My guess is that rather than a "binder" it is a perfect soluable mix (water)

So in effect we are talking about 80 proof vodka here.

The Vapor Pressure for ethanol is: 40 mmHg @ 13°C

My guess is that the vapor pressure for water is such that they both are reduced equally.

If you spilled alcohol and water seperatly the alcohol would evaporate before the water, but when we set down our adult beverage and pick it up sometime later we may be confident that its highly sought after properties remain undiminished.

I'm soon to be off to the lab (liquor cabinet) to prepare further experiments. >snort<
 
Fishtales":poj6th2q said:
Question is as follows....

I filled a glass with 40% ethanol solution and left it open on the lab bench. When I came back next morning to the lab, I found that the ethanol concentration in the glass was still 40%. How is this?
Click to expand...

How many times was the glass refilled?

When was the last refilling of the glass?

And by whom?

And furthermore:

How was the % of ethanol determined?

Did it taste the same before, during, and after the investigation?

How was your day home on sick leave?

How many days did the experiment set back your retirement date?

Is there anyone else you can blame this on?

Maybe this guy?

fire-breathing-7.jpg


Joe. :lol:
 
Properties of ethanol-water mixtures. The numbers of H bonds per water and per ethanol decrease as the mole fraction of ethanol increases.
 
Maybe it's a Whack-a-Mole Glass?


:cocktail :cocktail :cocktail :cocktail :cocktail :cocktail :cocktail :cocktail :cocktail :cocktail

Or a "Whack-a-Mole Cocktail?

:cocktail :cocktail :cocktail :cocktail :cocktail :cocktail :cocktail :cocktail :cocktail :cocktail

Joe. :teeth
 
Brrent-

I had to research that one! (Only have a vague memory of ever seeing one of those games.)

Maybe we should have a "Whack-a-Mole Cocktail Contest" at one of the C-Brat Get-Togethers?

Just kidding!

Joe. :wink:
 
It should be fun. Maybe Whack a Bayliner would have more meaning.

I played Whack a Mole in the arcade but got hooked on foosball in college. Bought a Irving Kaye foosball table. It is built like their pool tables. Heavy, sturdy and long lasting.
 
I missed out on some of this.... is that how you pronounce "guacamole"?

John

My guacamole does not disappear overnite, it just turns black...
 
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