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Need to chill your beer? I’ve got the solution

After a long, hot day, would could be better than an ice-cold beer? jimflix!/Flickr

It’s now my second summer in Australia. The first wasn’t too bad but this year the frequency of days in the high-30s is a little too high for this English girl. Today’s going to hit 39°C in Melbourne, and the cooling at my place is broken. I think I’ll stay in the lab today and take advantage of the synchrotron’s steady 23°C and wait for things to chill off this evening.

But the one thing that would take the edge off this evening is one of the beers I’ve got, ah, not in the fridge. Well that puts a dampener on things.

Putting beer on ice is a good option … but we can do better. Speed Light

But perhaps there is a way to speed up the cooling of my after-work-on-a-39-degree-day beer.

I could put in the freezer, but the rule of thumb for temperature control is that you want to maximise contact between your sample (the beer) and the coolant. I think I could do a little better than a few cold air molecules bumping into the sample every so often.

The standard tool of an ice bath is a super idea. Floating enough ice in water will mean that the whole thing will equilibrate for a good long while (until all the ice melts) at the melting point of the ice, 0°C. But things would speed up if you could equilibrate the mixture of ice at a lower temperature.

The trick is to make the water into a solution by dissolving something into it. It doesn’t even really matter what you dissolve into the water – though table salt is what you’re most likely to have – the effect will get stronger with the more materials added and dissolved into it. This effect is known as freezing point depression.

Try it later if you like: take 1 cup of table salt and dissolve in 3 cups of water. Add lots of ice and you should get a cooling bath for your stubbies that’s below -10°C. Hey, by the end of today you might even fancy a dunk in it yourself!

Here’s the beer cooling effect demoed. (And of course you know that it’s thermodynamics rather than chemistry at play now!)

But it doesn’t have to be table salt to cause this effect (though I would only recommend using table salt at home); anything that dissolves into water will have this effect. It’s the freezing point depression effect that is thought to have formed much of the super-varied landforms we see on the icy moons of the solar system, worlds like Saturn’s Enceladus and Jupiter’s Europa.

There’s not much sunlight that reaches out to Jupiter and Saturn and the daily temperature at Europa, for instance, is a chilly -150°C. If these moons were only made of pure ice, chances are we’d not see half the weird landforms we do. So something is mixing with the ice to allow it to melt sometimes, to form the strange alien landscapes that we see on this moon.

This mosaic of the Conamara Chaos region on Jupiter’s moon, Europa, clearly indicates relatively recent resurfacing on Europa’s surface. Irregularly shaped blocks of water ice were formed by the break up and movement of the existing crust. The blocks were shifted, rotated, and even tipped and partially submerged within a mobile material that was either liquid water, warm mobile ice, or an ice and water slush. NASA/JPL

One of the things I’ve been investigating at the synchrotron has been mixtures of sulfuric acid and water. When frozen these mixtures form a variety of solids, made up of sulfate (a sulfur atom bonded to four oxygen atoms) and water molecules.

Each of these solids form with different numbers of water molecules, and in a variety of crystal structures. These sulfate and water solids, known as hydrates, are thought to be all over the surface of Jupiter’s moon Europa, with the sulfate being spewed from Europa’s sister moon Io.

Adding sulphuric acid to water has quite a large freezing point depression effect. In fact, in the correct proportions the solution will not freeze to -73°C. This stronger effect is probably due to the sulfate molecules interacting a bit more strongly than table salt would with the water molecules. -73°C is a bit of an overkill (not to mention dangerous with high-concentrations of acid) to cool your beer but temperatures just below the surface of Europa could easily reach this point, probably higher, allowing for melting and possible volcano-like activity.

I’m taking the fact that I can only consider drinking beer ice cold as sign I’m rapidly adopting the Australian way of life. And, in future, I will endeavour to get my beers in the fridge early when hot days are forecast.

Join the conversation

13 Comments sorted by

  1. Jane Rawson

    Editor, Energy & Environment at The Conversation

    Useful science! I remember in high school our teacher showing us how wrapping a cloth soaked in methylated spirits around a stubby would cool it in no time at all. Might have been the only time the whole class paid attention...

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    1. terry lockwood

      maths/media/music/drama teacher

      In reply to Jane Rawson

      I spent a wonderful afternoon recently at Maclarenvale wrapping my fizzy white glass with a damp paper napkin wrapped around it. It was 40 deg and windy but this seemed to keep the contents cooler. I had a spray bottle to keep the paper wet. Low tech is good tech.

      I now make this a general practice at various beer/music venues all in the name of research. It is going to be a research project for my science students come February minus the beer.

      p.s. Where was the 'don't try this at home kids' note on the sulfuric acid bit, Helen?

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  2. Sean Manning

    Physicist

    Great article.
    I often wrap a wet paper towel around the drink beofre putting it into the freezer. No where near as fast as a sub zero ice bath but still pretty good.

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  3. Elizabeth Bathory

    9-5 project drone.

    This gets my vote for best article on The Conversation EVER.

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  4. Sue Ieraci

    Public hospital clinician

    Great bit of science....isn't this also why you put salt into the ice-water in your old-fashioned ice-cream churn?

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  5. Petar Rajic

    Researcher

    I remember a similar experiment with a soft drink bottle in high school - my Chemistry teacher used methylated spirits and water, explaining that she would never use salt as it would be irresponsible to release it into an already heavily-saline river system (as we were in an inland city at height of drought, where treated sewerage was apparently released into the Murray-Darling system).
    Throwing the used saline solution recommended by the author into stormwater drains would be irresponsible in any context, but we wouldn't have to worry about pouring it down household drains in coastal cities as long as sewerage is dumped into the sea, right?

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  6. Ahelmil Arun

    logged in via Facebook

    As a ex Brit myself, I can understand the longing for a cold stubbie, but, and it's a big but: is it beer? The pale gold liquid so tasty on a hot day here in Oz just isn't the brown nectar of olde England, drunk in a sleet storm by a roaring fire in an unfriendly pub!

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  7. Roger Carter

    logged in via Facebook

    This is what we need, more immigrants with real skills like this! Let's face it, cooling beer fast is one of the true technical challenges of our time and you have given us some great hints here.
    OK, I am now planning my concentrated sulfuric acid beer cooling bath; but one thing is worrying me. What will happen when I snatch the bottle out of the bath, whip off the top, put it to my lips and up end it? I can just picture those concentrated sulfuric acid drops running down onto my lips... I leave the rest to your imagination.

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  8. Arthur James Egleton Robey

    Industrial Electrician

    Things are improving since I was a young man. See all the women on this site taking beer seriously.
    I can die peacefully now. The world is in good hands.

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  9. John Kelmar

    Small Business Consultant

    Interesting, but not always practical, except for the salt addition.

    However I used to pack Dry Ice into my portable cooler when I went on a camping trip. This was great for the beer, as i used to place a beer can on the Dry Ice for about 10 seconds and found that it cooled to around its freezing point in that time - don't try this with a glass bottle.

    Dry Ice kept the meat frozen for five days, but made the eggs go "bubbly".

    The best thing was there was no residue left when the Dry Ice melted/evaporated, so all my food remained clean and dry.

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  10. Mat Hardy

    Lecturer in Middle East Studies at Deakin University

    One of the great and eternal debates I remember was whether it was better to leave the plug in or out of the bath when using it to store ice and beer. Which method would cause the ice to melt faster and/or the beers to stay colder for longer?

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    1. Roger Carter

      logged in via Facebook

      In reply to Mat Hardy

      My amateur guess would be to leave the water in and not drain it. As you drain the very cold water out you are replacing the spaces between the ice with ambient temperature air which will make it melt faster. Also, the water increases the cooling contact area with the bottles. As water has a very high specific heat, the just melted ice water is a good medium to transfer the heat from the bottles (it has a high capacity to absorb heat).
      Those with more up to date thermodynamics feel free to correct me...

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  11. Dan Carter

    Soil Scientist

    Boys in the bush fill an esky with dry pelleted urea, add warm beer, add water and get nearly instantly cold beer. The dissolution of urea in water is highly endothermic ie heat is taken out of the water and the mixture chills the beer rapidly. Caution: stubbies are slippery when taken out and the dissolved urea solution is too concentrated for plants. Please dilute before disposal, because it makes a for a good lawn fertiliser.

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