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Physics of alcohol

Kwazy

Shared on Mon, 03/02/2009 - 16:25

In the Kwazy Household the vodka is stored in the most logical of places:  the freezer.  Last night the wife asked me to make her a martini.  After having fninished doing so, I left the 1/3 full 1.75L bottle of Kettle One on the kitchen counter instead of putting it away as I figured I'd make myself one in a few minutes.

A few minutes turned out to be an hour later.  Turns out that stuff about the ideal gas law from high school physics actually has real-world applications. 

Remember p1v1/t2 = p2v2/t2 ?

Well in this case, the volume in the bottle remained constant, thus we can use Charles Law stating p1/t1 = p2/t2

Without getting into the acutal math, we can just say that this means that if you tightly cap a bottle of vodka at 4 degrees after pouring a martini and let it  rise to the ambient room temperature of 70 degrees, the pressure inside the bottle will increase quite a bit.

And of more practical note:  If you decide to have a second martini after the temperature increase, when the last thread from the cap disengages from the bottle it will propel the cap up towards the ceiling with sufficient force to take out a lightbulb.

Lesson learned.

Comments

Flywalker's picture
Submitted by Flywalker on Mon, 03/02/2009 - 17:00
WHAT!!!!! Who the hell do you think is reading your blog?
NewBoyX's picture
Submitted by NewBoyX on Mon, 03/02/2009 - 17:06
Been there, done that.
Devonsangel's picture
Submitted by Devonsangel on Mon, 03/02/2009 - 17:44
LMAO! Seriously, how much of that did you remember and how much did you have to look up?????
Kwazy's picture
Submitted by Kwazy on Mon, 03/02/2009 - 17:50
:) I remembered the ideal gas law, but I couldn't remember if Boyles' or Charles' Law isolated pressure/time from volume...had to look that up.
pyr0lyZer's picture
Submitted by pyr0lyZer on Mon, 03/02/2009 - 17:56
Ahh..Physics...my favorite subject of all time. With a little thermodynamics thrown in!! In this case, though, the one big assumption is that the state change from 1 to 2 was quasi-steady state, otherwise these equations don't apply and you have to integrate the phase changes over time...yes, I'm just trying to sound smart. I'm probably wrong but I think I'm close if I remember my thermo correctly.
Kwazy's picture
Submitted by Kwazy on Mon, 03/02/2009 - 18:05
Assuming equilibrium is attained, I wouldn't see how steady-state would be a requirement as we're not measuring the rate at which the variables changed. Then again, the principle prop of the experiment has resulted in considerable cerebral atrophy over the years.
LtBlarg's picture
Submitted by LtBlarg on Mon, 03/02/2009 - 18:21
Very Funny !!!
KittenMag's picture
Submitted by KittenMag on Mon, 03/02/2009 - 23:36
I don't buy it... write out a full formula or it doesn't it count.
NewBoyX's picture
Submitted by NewBoyX on Tue, 03/03/2009 - 05:38
Remember to always show your work.
Kwazy's picture
Submitted by Kwazy on Tue, 03/03/2009 - 08:51
@Kitten...OK, I'll go for it. No laughing from the teachers! Assuming the glass bottle as a solid pressure vessel, we can call volume constant such that v1=v2. Air is not an ideal gas (there is no such thing), but over this temperature and pressure range behaves very similarly, so we will assume it is. The temperatures must be converted to an absolute scale to allow them to be used in any ideal gas equation. To convert to Rankine we add 460 to each, so t1=464R and t2=530R. We'll assume standard atmospheric pressure for the house since I don't have a barometer...t1=14.7psia Solving Charles' law for the only unknown variable is p2, thus: p2 = (p1 * t2) / t1 p2 = (14.7 * 530) / 464 p2 = 16.8 psi Subtracting out the atmospheric pressure, 16.8-14.7 = 2.1 psi increase. That doesn't sound like a lot, but the bottle cap weighs much less than an ounce, and halogen lamp bulbs are rather delicate :D

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