http://www.dumblittleman.com/2007/07/how-to-chill-hot-beer-or-soda-in-3.html
ok Massimo what is the physic behind this? I thing the salt change the way the ice loose calor. Explain and justify your degree.
zerocold
http://www.dumblittleman.com/2007/07/how-to-chill-hot-beer-or-soda-in-3.html
ok Massimo what is the physic behind this? I thing the salt change the way the ice loose calor. Explain and justify your degree.
zerocold
July 9, 2007 at 6:24 pm |
Hey Zero, my name is Tommaso!
Anyway, I think the trick consists in using a liquid of high thermal conductivity to transfer heat away from the beer cans. Water is not a very good conductor of heat. Salt water is a better one. By adding salt to water you allow the heat to transfer more efficiently from the beer to the iced water. Further putting the container in the fridge helps reducing the temperature increase of the water.
Cheers,
T.
July 9, 2007 at 6:56 pm |
Hi TOMMASO, I’m so sorry, but all is due to the heavy drugs that I used to take when I was younger…
Anyway thanks for he explenation, I’m thinking of an exercice to assign to my private students to make them better understood thermodynamics.
Zero
July 10, 2007 at 12:22 pm |
[...] explains how to use salt to cool beer. That is, he asks for an explanation of the [...]
July 10, 2007 at 12:32 pm |
I can’t find the data on the difference in thermal conductivity between water and salt water, but I don’t think it’s enough to explain this effect. The salt does, however, lower the freezing point of the water a little bit. Then the ice can melt and in doing so draw lots of heat from the environment. The latent heat of melting for ice is significant. I found one person giving this explanation (ScienceTim) in the comments here:
http://blog.washingtonpost.com/achenblog/2006/01/toms_dumb_question_salt_water_1.html
July 10, 2007 at 8:21 pm |
Chase is right. By solving the salt into the icecubes, the entropy of the system will increase. But to be able to melt the icecubes, energy must come from somewhere. This energy is drawn from the hot beer.
July 10, 2007 at 8:47 pm |
Geez Tommaso, mu mum explained this to me in the context of making ice cream the old way. Zero should ask someones mum next time. Chase has the right of it.
July 15, 2007 at 11:31 pm |
Yes, I cannot justify my degree with thermodynamics… I long forgot most of it. Moreover, my guess that the conductivity of water was greatly increased by salinity is also wrong.
Indeed, it took me a good 15 minutes of advanced searching before I could put my hands on some unrestricted-access data on water thermal conductivity curves as a function of NaCl concentrations. And, lo and behold, it seems that the addition of water *decreases* the conductivity!
Here is the source:
http://www.osti.gov/bridge/servlets/purl/6269880-iPJPhB/6269880.PDF
Thermodynamics is indeed mysterious.
Cheers,
T.
August 19, 2007 at 11:00 pm |
i think its all about latent heat, the temperature change of the surroundings is most prevelant at the time of the change of state, ie the ice melting, so when the ice melts it is mixed faster with the water, so it will not work for as long, so, the longer the party the lower the concentration of salt, just a guess, i aint got no degrees or such the like, but it definitely works quicker than just water and ice alone, tell me if im wrong like, the other explanation involving the energy been drawn from the tinnies makes sense in my mind too, it does seem similar to my way of thinking
October 2, 2007 at 3:22 pm |
Great ideas and thoughts…it is about several thermodynamic concepts that make this magic happen. First, water has a large capacity for holding heat (not high heat conductivity), so the water can absorb the heat from the beer. Mixing helps the heat conductivity of the beer can-water mixture, moving cold water up next to the beer cans by mixing things around. Having ice in the water keeps the temperature differential high (cold water – warm beer); the larger the temperature differential, the faster the cooling process. The salt actually lowers (really!) the freezing point of the water so the mixture gets COLDER! Since this creates a larger temperature differential, the beer cools faster, and the party can continue that much sooner. Check this site out to learn more about the wonders of salt and water:
http://www.worsleyschool.net/science/files/saltandfreezing/ofwater.html
January 7, 2009 at 1:39 pm |
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October 12, 2009 at 8:33 am |
I’ve seen it as, the salt lowers the melting point of the ice, melting it while keeping its temperature, thus giving better contact to the warm container. Two liquids of differing temperatures (the melted ice and the coldish water) sum their temperatures faster than a solid and a liquid.