Comments on: Cocktails: The Science of Shaking http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/ The International Culinary Center's Tech 'N Stuff Blog Thu, 09 Jan 2014 18:17:16 +0000 hourly 1 http://wordpress.org/?v=4.0 By: davearnold http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-97227 Tue, 20 Sep 2011 22:16:57 +0000 http://www.cookingissues.com/?p=1491#comment-97227 You need to shake an ethanol solution with ice –not on its own. The same phenomenon is at work here as when you add salt to ice to make ice cream. The temperature of the whole system drops below it’s initial temperature. It’s all about entropy.

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By: davearnold http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-97223 Tue, 20 Sep 2011 22:15:12 +0000 http://www.cookingissues.com/?p=1491#comment-97223 If you take pure ice at 0 C and any ethanol solution and shake them, the temperature of the whole system (including the ice) will drop below 0. Shaking pure water in pure ice is different, the system will stay at 0 C. The ethanol in the liquid changes the balance of the Gibbs equation making the melting of ice favorable at 0 C. The temperature of everything will drop until the heat required to melt the ice is matched by the entropy win of melting into an ethanol solution.

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By: Emilie http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-97105 Tue, 20 Sep 2011 18:00:55 +0000 http://www.cookingissues.com/?p=1491#comment-97105 While I agree that it is the presence of alcohol that seems to be the explanation – I really could not understand your explanation on August 10. I do wonder if you were to just shake alcohol on its own, whether its temperature will lower. I think I’ll try this at home if my thermometer allows such a thing.

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By: Emilie http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-97097 Tue, 20 Sep 2011 17:46:08 +0000 http://www.cookingissues.com/?p=1491#comment-97097 That is correct — but I thought the question was whether shaking water with ice will turn the resulting stuff into something colder than ice. We are not talking about supercooling water, which I thought was something different entirely (but I could be mistaken). In any case, I actually asked a professor in thermodynamics this question — and will try to post whatever he says — I wasted too much time trying to read up on the laws of thermodynamics on my own. I did learn a lot, but nothing that would help me actually answer this particular question. It may have to do with the way alcohol evaporates.

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By: davearnold http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-96259 Mon, 19 Sep 2011 18:57:43 +0000 http://www.cookingissues.com/?p=1491#comment-96259 What I am saying is you can’t supercool water with ice crystals present in the water because the water will freeze onto the crystals instead of supercooling. When you supercool water and introduce some sort of nucleation site, ice crystals immediately begin to form and the temperature of the water rises to the freezing point. Further supercooling will be impossible.

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By: Emilie http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-93878 Fri, 16 Sep 2011 17:17:16 +0000 http://www.cookingissues.com/?p=1491#comment-93878 I don’t understand this “it would be very difficult to supercool pure water with ice crystals already present” — in the Modernist Cuisine, they talk about supercooled water (which actually remains liquid below freezing temperature because it is pure). I haven’t had the time to conduct the supercool water experiment, but relying on the Modernist Cuisine, your water plus ice will just turn to ice.

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By: davearnold http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-73732 Wed, 10 Aug 2011 14:41:55 +0000 http://www.cookingissues.com/?p=1491#comment-73732 Howdy Chris,
The alcohol is the reason the temperature goes lower than 0C. Water and ice by themselves will never go below 0 C (even with external chilling, because it would be very difficult to supercool pure water with ice crystals already present). The reason the cocktail system goes below 0C is that it is energetically favored for ice to melt into a water/ethanol mixture even at 0C. When that ice melts into the ethanol mixture, heat is required (it takes energy in the form of heat to melt the ice). That heat doesn’t make the ice hotter, it just changes the water from solid ice to liquid water. That required heat (the heat of fusion of water) needs to come from somewhere, and it isn’t from the environment (heat leaking from the environment into a cocktail shaker isn’t fast enough). The heat comes from the remaining ice and the drink itself. If you remove heat from something without changing its phase, it gets colder –so the drink gets colder.

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By: Chris http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-70101 Tue, 02 Aug 2011 23:21:40 +0000 http://www.cookingissues.com/?p=1491#comment-70101 I am following this idea, but there is one thing I do not understand. If melting ice absorbs heat (read: gets hotter), and ice melts at 0 degrees C, and your ice is also 0 degrees C, then how, upon absorbing heat, does it remain ice?

You mention that alcohol’s freezing point does not answer this question. What results are achieved using water instead of alcohol? I believe it is possible to cool water below 0, but not by much without adding anything. I understand the point of your post, but remain unconvinced that the alcohol not the primary reason for achieving these temperatures. I would like to see what temperature is achieved using water only in the shaker. I don’t think it would be quite so low, but am no expert.

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By: Dr. Justin's Dad http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-7566 Mon, 06 Sep 2010 23:57:26 +0000 http://www.cookingissues.com/?p=1491#comment-7566 But on balance this article is pretty good. Congrats for actually doing the experiment. For accuracy you have Judith Miller beat, hands down.

You probably don’t want someone with a PhD in physical chemistry to intrude here but:

“Things want to go to a lower energy state. Things are lazy.”

Sorry, things are not lazy, nor are they industrious. Things don’t care. The reason that a system will go to a state of lower energy is that when the energy from the system is dissipated to the surroundings, there is an entropy gain of the surroundings. Changes in entropy are the only driving force for anything.

“So who wins, enthalpy or entropy?”

It is always entropy, entropy is the only thing that matters, for driving a process. At low temperature the entropy of the surroundings wins. Ice freezes at low T because the entropy gain from dissipating heat (the enthalpy of freezing) to the surroundings beats the entropy loss in the system (from ordering the water molecules in the crystal). At high T the direction switches (ice melts) because the entropy gain from dissipating heat is less than at low T. It is all entropy, all the time. You just have to do the accounting.

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By: davearnold http://www.cookingissues.com/2009/07/22/cocktails-the-science-of-shaking/#comment-5392 Sat, 26 Jun 2010 21:12:21 +0000 http://www.cookingissues.com/?p=1491#comment-5392 Good question. It depends on the ambient temperature, the mass of the cocktail, amount of ice present, etc. I haven’t done the measurements in a while, but the answer is … a pretty long time if ice is present, not long if ice isn’t present.

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