Question

For keeping goods cold during shipment, what is an advantage of dry ice (frozen carbon dioxide) ver water ice?

Answer 1

Well first off, the sublimation point of `CO_2` is `-78.5` `""^@C`. The freezing point of water is of course `0` `""^@C`.

Explanation:

So the temperature differential is clearly a factor in the shipping of frozen goods, or even semi-frozen goods like ice cream. As an added bonus, carbon dioxide sublimes at normal pressures; it doesn't melt as ice does, and slosh around in the bottom of your cooler. All this being said, most stuff is shipped using standard refrigeration units.

And all this for the price of global warming! (Of course, the dry ice would be obtained from fractional distillation of air, and further processing.)