Why did the beer freeze?

Tom Mattson

OK, so I'm at my favorite watering hole last weekend, and someone orders a Corona with lime. The bartender puts the lime in, and the beer starts to freeze. Everyone in the place looks at me and asks me why, and I don't know. "Don't you know anything useful?" they demand, but I can only stammer something about how thermo isn't my specialty.

So, anyone have any ideas? Or do I have to find a new place to hang out?

BoulderHead

The only idea I would have is to make sure any new hangout serves cold Coronas.

While waiting for a chemist I'd like to throw in a couple more to see if anyone has ever encounter that;

1) Ice melts faster in plain old water than in sugar water (well, a coke that is).
2) Coffee seems less viscous than water and sloshes about readily.

mcleodnine

First guess would have to be that the lime or parts of it acted as a seed crytal for the ice to form.

Mike H

Tom,

Back in the old days before current refrigeration methods, people would develop what might be termed "freezing solutions" - basically if you mixed a certain proportion of chemicals together, upon dissolving and reacting, they'd cause the solution to cool. Usually it involved some acidic compound, a basic compound, and a neutral compound (typically a salt) as memory serves. Am guessing that the introduction of the lime (and its associated citric acid and such) started such a reaction and caused freezing. The entire beer didn't freeze (right?) and it was just around where the lime (or its sqeezed juice) was introduced to the Corona. So yes, it was a matter of thermodynamics after all, heh. As for specific compounds reacting, am not totally sure. Might make an interesting experiment, though. Anyone willing to splurge for a case of Corona and some limes for me to analyze? :)

BoulderHead,

When you dissolve sugar in water (or other reasonably soluble compounds in a liquid), you lower the liquid's freezing point (blame colligative properties) by a certain amount. As such, if you were to toss ice cubes into the liquid, the ice cubes are that much further above the freezing point than they otherwise would be with plain water. Of course, with Coke (or other carbonated soft drinks), they tend to be slightly corrosive to begin with (just ask your dentist), so that probably accelerates things as well. As for coffee being less viscous, speaking as a long time coffee drinker, I've never noticed coffee being less viscous. I know (at least in my experience) instant coffees tend to be basically just be hot water with some grains dissolved in them, but well brewed coffee normally has some body and bite to it. Once again, I'd be willing to conduct such a study (although you'd probably have to fund the coffee habit of my entire lab - where we've named our workstations after coffee types).

mcleodnine

MikeH - so would that mean there's an endothermic reation taking place when the lime juice meets the chilled beer?

My initial reply was based on my understanding of what I've heard referred to as 'cold-filtered' or 'ice-filtered' beer. Chilling the beer causes ice to form with crystal growth starting on sediments or precipitates in the brew. Skimming the ice from the batch removes this junk and also raises the alcohol content.

BoulderHead - I've never noticed coffee to be less viscous unless transported in a styrofoam cup for a long commute to work. The proximity of wool clothing also seems to enhance the effect.

Mike H

mcleodnine, a big yep to the endothermic reaction part. I should probably reiterate that depending on what combination of chemicals you're working with, some of the effect will be due to the dissolving process and not necessarily any reaction which may take place. I should note that the old fashioned freezing solutions were fashioned so that you'd have a container of water in a larger container, and in the space between the water container and the vessel you'd whip up your freezing solution, sucking energy out of the water and causing it to freeze. That way you wouldn't have who knows what chemicals in your fresh new ice.

Am not sure on how beer is processed after it's been filtered, although it's conceivable there might some effect due to nucleation, especially if the lime is cold enough.

BoulderHead

Mcleodnine,
Yes, the ‘solution’ to my question might be found in the properties of attraction where the nicer the clothes being worn and the more important the event you’re going to, the more likely it is to be spilled (demon possessed coffee perhaps?).
What I thought I was observing on occasion was that I could carry a cup of water without much problem at all but fill the cup with an equal amount of coffee and the slightest movement seemed to cause the coffee to slosh further up the side of the cup. Eventually I concluded that the coffee might be lowering the viscosity of the water or some such thing as that.

Mike H,
Now I’m confused. When you say that the properties of the Coke might accelerate things are you saying that the ice would melt quicker in the Coke? ‘Cause what I’ve noticed would be the opposite. Do I understand correctly that by lowering the freezing point of the water (adding sugar) the transfer of energy between the solution and the ice-cube is slowed down in some way, causing the ice to take longer to melt?
I think walking with a cup of coffee in one hand and a cup of water in the other, then switching which hand you are doing the holding in (to minimize bias), might be a quick way to determine if I have actually stumbled onto something or just crazy….
That sounds expensive, how about if I send you guys a box of donuts instead. [:D]

Artman

Hot liquids are less viscous then cold liquids (as an example, heating oil to make it flow), but I don't think there would be much difference between the viscousity of hot water and equally hot coffee.

Just throwing out a possibility here, if the beer was stored at a subfreezing point for water, but above the freezing point of beer, which I would think would be a little lower due to the small alcohol content, could the lime juice have seperated the water from the alcohol the way lemon juice seperates grease and water, allowing the lower temperature to freeze the water? Sound possible?

BoulderHead

*slaps forehead*
Yes, it might have only been that all along, thanks.

Artman

Then again, it may just be the attraction to clothing, which does seem to increase directly with the quality of the garment.

I have noticed two other relationships: The attraction to clothing increases inversely proportional with the darkness of the coffee to the lightness of the fabric, and the probability of a staining spill is greater increased when the pants are part of a suit.

BoulderHead

Drat the luck, I was hoping Demons would have been involved in this. I could have constructed a magic circle of half-filled coffee cups resting upon a priceless Persian rug and challenged the powers of Darkness….
Instead I’ll just have to be more careful next time. [:D]

Tom Mattson

OK, I'm taking this as my first lead. I'm going back there tonight and asking the bartender to put a small cup of water in the cooler. If it freezes, then I'll start looking up colligative properties in my chem book.

FZ+

Or maybe you are in a state of heightened awareness when the coffee is around? Perhaps it causes locallised time dilation of a sort....

climbhi

Are you carrying the coffee in the same type of cup, it might be that there is less surface tension with the coffee and whatever kind of cup it is being held by (here at my campus the coffee cups seem really slick on the inside) then there is with the water and whatever kind of cup it is in (assuming a standard glass cup). But if you have them in the exact same cup then my only guess is the difference in heat.

Mike H

BoulderHead,

Managed to think it over again, and there are probably a couple of effects going on in solution. Soft drinks are usually slightly acidic, and therefore a bit more reactive than pure water, which alone might accelerate things. However, I think probably the drive towards equilibrium probably outweighs it - you have a mixture of sugar and water (and other things) in the Coke, and just (essentially) pure water in the form of ice.

ObsessiveMathsFreak

I think sherbert causes the same effect in water, or is it lemonade. people used to put it in their drink to keep cool in the days before refridgeraters, and hence ice at the time.

Just some kind of endothermic reaction.

But maybe cryatals are involved.

Do you want to know the scary part.

You friend, after seeing this bizzare reaction, DRANK the liquid. Go figure.

Tom Mattson

OK, I tested this by having the bartender put a cup of water in the same cooler as the Coronas, and it did not freeze even after a few hours.

OK, this is the next contestant on The Theory is Right. Does anyone have any references for this? I've never studied crystal growth.