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I just stumbled across an ancient video of some people putting a 60 pound block of dry ice in a swimming pool. Pretty cool stuff.

It's pretty interesting to me that in the video, the dry ice sublimates much quicker in the water than in the air.

I am wondering why this might be? Is it possible that water is acting as some sort of catalyst? If so, how can I picture this on a microscopic level? (That might not be possible to answer but the catalyst portion is.)

I was thinking that the $\ce{CO2}$ might be motivated to form carbonic acid, and by Le Chatelier's principle, the dry ice would sublimate even faster.

I'm not so sure that makes sense though...

I don't know. Any thoughts?

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  • $\begingroup$ Try it with water ice. With a bit of patience, you'll see the effect is still there - ice melts faster in water than in air. So, no - carbon dioxide is not the magic part, and neither is the solvent. What else is a difference between water and air? :) (hint: did you ever swim in cold weather? Which felt colder, water or the air?) $\endgroup$ – Luaan Sep 17 '15 at 14:08
  • $\begingroup$ Note that this doesn't happen with small amounts of dry ice -- there's so little convective motion that the water next to the ice freezes and insulates it. It's like a solid phase Leidenfrost effect but I'm not aware of any particular name associated with the process. $\endgroup$ – Eric Towers Sep 17 '15 at 14:09
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It's just about heat capacity + heat conductance, nothing more. $\ce{CO2}$ sublimates much quicker in the water because water is much better at heat exchange than air. Anybody who ever experienced swimming in water at 15°C and walking in air at 15°C can attest to that.

Catalysts for heat exchange are usually made of copper and other metals. (Also, usually they are not called catalysts.) You have one in your computer, attached to the CPU.

As to formation of carbonic acid, it hardly has any influence on the process (though it does happen to a certain extent, of course). Most $\ce{CO2}$ escapes in gaseous form anyway.

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