MadSci Network: Chemistry |
I discussed this experiment with some of my colleagues and we think that the CO2 (carbon dioxide) causes a stirring effect which distributes the temperature more evenly in the soda. The ice cubes serve as nucleation sites for the bubbles (a place for bubbles to grow). As the bubbles grow and then release they cause the ice cubes to circulate in the liquid. This circulation causes the warmer layer below the ice to mix with the colder upper layer of soda and ice. Have you ever noticed that when you use a straw to drink a liquid that the liquid at at the bottom of the cup is warm and requires a stir to evenly distibute the cooling? The "still" beverages (water and tea have no bubbles) will have a cold layer on top next to the ice and a warmer layer on the bottom. This would cause the ice to melt slower.
Here is an experiment to try. Allow some soda to get flat overnite, then try the experiment again. This was a really terrific question!! Keep up the good work and I'll see in the lab soon!!
Mad Scientist Dave
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