Science Buddies: "Ask an Expert"

We performed an experiment measuring the rate of cooling for Dr. Pepper, Diet Coke, Water, Milk and OJ. This was the order from the fastest to cool to slower. Can you help us explain why carbonated drinks cooled faster than water ????

Hello and welcome to the forum.

You need to know what is in your carbonated drink. Is it a sugary soda? If so, it has a lot of corn syrup in it. What you're looking at is the specific heat of these two substances. Use your favorite search engine to investigate the specific heat of water versus whatever is in your carbonated beverage. I found that corn syrup has a specific heat about 65% that of water, so I would expect corn syrup to cool about 50% faster than water. Good luck and let us know what you find out!

Keith

Thank you for your assistance. This is very helpful in our research. Unfortunately, I can't find a website that publishes the specific heat capacity of corn syrup or high fructose corn syrup. Can you point me to a few ?

Hi: I just used google to search "specific heat corn syrup" and found this: http://www.gaumer.com/Resources/RefLiquids.pdf
HTH
Keith

It kind of depends on the exact conditions in which you measured the cooling. A factor to consider is that the CO2 bubbles rising up through the beverage will cause some heat transfer by convection. The bubbles will pick up heat and water vapor as they rise. The bubbles will also tend to mix the liquid, which means that the temperature will be more even throughout the liquid. I'd investigate "diffusion" as it pertains to heat transfer.

One way to tell the difference might be to stir the liquids gently during cooling and see if that reduces the variation.

Stirring, even gentle stirring has some side-effects. Whatever material you introduce to stir with will have differential surface tension between liquid and gas phases (as will the inside surface of the container). The additional fluid forces resulting from stirring will change the dynamics of the what is happening. If you are using different liquids, the difference in surface tension between them combined with stirring forces may create more of a difference in behavior than the original effect you were attempting to test.