MadSci Network: Chemistry
Query:

Re: Does carbonated water freeze faster than non-carbonated water?

Date: Mon Mar 6 17:49:03 2000
Posted By: Raymond Cheong, Undergraduate, Chemical Engineering, University of Maryland
Area of science: Chemistry
ID: 952044283.Ch
Message:

Hi Carol,

In general, the temperature at which a liqiud freezes decreases as the concentration of dissolved materials increases. In the case of carbonated water, carbon dioxide dissolves as:

CO2 + H2O --> H+ + HCO3-

So, it is actually dissolved HCO3- in solution that would change the freezing point.

But don't confuse freezing temperature with rate of freezing. All other things being equal, the rate is dependent on the thermal conductivity: a measure of how fast heat can be added/removed. According to a previ ous MADSci response impure water has a slightly smaller thermal conductivity. Therefore, I would predict that carbonated water freezes slightly slower than non-carbonated water.

In fact, you could very easily test this at home. Take two identical cups, and put in equal amounts of water and carbonated water. Let them sit at room temperature, then place them in the freezer. This way, the container and initial temperature are controlled (i.e. the same). Periodically check the cups to see if the water has frozen, but don't move or disturb the cups. You will probably want to try it several times to see if you get same result.

Thanks for the good question, and stay curious!

Your MAD Scientist,
Raymond Cheong


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