How many times have gone to the fridge for a drink, only to find that your favorite cans aren’t in there? It’s 90 degrees out and you’re thirsty! Now, you’ve got to find the fastest way possible to chill your lukewarm cola. No worries. Science to the rescue!
Which method is the fastest way to cool a can of soda?
- 3 cans of soda
- Access to 1 freezer
- 1 wet paper towel
- 2 tablespoon salt
- 1 pot of ice
- Plastic wrap
- 3 rubber bands
- Set up your salted ice water bath by dissolving the 2 tablespoons of salt in water and adding it to a pot of ice.
- After a minute, use your thermometer to record the temperature of your ice bath.
- Using your thermometer, record the temperature of the freezer.
- Open the cans of soda and record the starting temperatures for each can, then seal them again with plastic wrap and a rubber band.
- Place your first can in the freezer.
- Wrap the wet paper towel around your second can and place it in the freezer.
- Place another can in the salted ice-water bath.
- Check the cans’ temperatures again after 5, 10, 15, and 20 minutes. Make sure to record the temperatures in your notebook each time.
- Plot your temperatures and times on graph paper.
You should have found that the salted ice water bath cooled the can to a good drinking temperature of about 44 degrees after about 5 minutes, while the wet paper towel can chilled the drink to the same temperature after around 10 minutes. The can in the freezer sould have only reached about 60 degrees or so (it needs a good 20 minutes to get nice and cold).
The salt lowers the freezing point of the water, allowing the ice in the ice bath to melt while still retaining its temperature. This makes the chilly water in the ice bath even colder. The paper towel can was also chilled fairly quickly because the as the water evaporates from the paper towel, it takes some of the can's heat away with it, causing the can to rapidly get colder. The poor freezer, while pretty cold, just didn’t make the grade because cold air just isn’t enough to do the job quickly. Water is a much better heat conductor than air, so heat is able to leave the can more quickly in the ice bath and wet paper towel setups.
There are countless ways to modify this experiment. You could add more cans of soda to get average temperatures for each freezing method. You can switch up methods by adding a fan and trying to cool the drink as it sits outside of the fridge. There are lots of new things to try when looking for an even better way to cool your drinks to a chilly 44 degrees. Just remember to use your creativity and everything you’ve learned about thermodynamics.