Science Smarts: Cool off
By PATTY ROOKS on July 22, 2023.
I was just listening to the weather report for this weekend and oh my it is going to be a HOT one; perhaps even record breaking temperatures. To be honest, it has been so hot for so long, I am running out of ways to cool off on these long hot summer days. Thanks to my summertime helpers, I was reminded of a fun way to do it at our house; and it even involves science. Let’s get started! *Remember to ask an adult before you do this experiment. Materials Two coffee cans – one large and one smaller so it will fit in the large one Duct tape Ice Coarse (pickling) salt Measuring cups Measuring spoons Sugar Heavy (whipping) cream Milk Vanilla Mixing spoon Procedure 1. Place the small coffee tin inside of the large tin. 2. Pack ice evenly between the two cans about 3/4 of the way up the sides. 3. Measure 175 mL (3/4 cup) milk into the small can. 4. Measure 250 mL (1 cup) of heavy cream. Pour into the small can. 5. Add 80 mL (1/3 cup) sugar. 6. Stir well. 7. Add 5 mL (1 tsp) of vanilla. 8. Make sure this is combined well and the sugar has been dissolved. You may have to stir it for a bit. 9. Put the lid on the smaller coffee can and secure in place with duct tape. 10. Fill the rest of the large coffee can with ice. It should be all of the way up the sides and perhaps on top of the small can. 11. Sprinkle 250 mL (1 cup) salt over the ice. 12. Put the lid on the large can and secure with duct tape also. 13. Shake, kick, and roll the can for at least 15 minutes and then check. 14. If the ice cream is not hard yet, you may have to add more ice and salt and shake some more. Make sure you put the lid back on! 15. Enjoy! What is going on? It always amazes me how ice cream forms so simply. The science behind making this delicious treat can be related to the science of melting those icy sidewalks in the winter. When salt and ice mix, the freezing point of the ice is lowered causing the ice to melt. Hmm, where is the heat coming from to cause the ice to melt you might wonder. Well, the heat that causes the ice to melt in this case is from the warmer cream mixture in the second container. This is why you have to keep shaking or kicking the can – by shaking the mixture up, you are continually moving the warmer cream mixture from the middle of the can to the outside where it can begin to freeze evenly. By lowering the temperature that the ice freezes in the container, we are able to create temperatures below 0°C which is necessary for the cream mixture to freeze into delicious creamy ice cream. Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at praxis@praxismh.ca, http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. Address: #12 826 11 Street S. E., Medicine Hat, Alberta, T1A 1T7 Phone: 403-527-5365, email: praxis@praxismh.ca. 36-35
