Praxis: Slushy science
By Medicine Hat News on July 21, 2018.
WOW! It has been a hot couple of weeks here in southeastern Alberta. I have to commend the people that work outside in such extreme temperatures. Next time you see a firefighter, policeman, construction worker, farmer or rancher (not to mention MANY more professionals), take a minute to say thank you for all they do. They endure not only the extremely hot temperatures in the summer but the extreme cold temperatures in the winter to help each and every one of us out every day in their careers. Well, I do not know about you, but I need to cool off. Here is a little something fun to try out when the temperatures rise! Let’s get started. *Remember to ask an adult before doing this experiment. Materials – measuring cups – large zipper baggie – medium zipper baggie – ice – coarse or rock salt – your favourite fruit juice – clean glass – straw Procedure 1. Measure 250 mL (one cup) of fruit juice. Carefully pour this into the medium zipper baggie. Zip the baggie closed. Set aside for now. 2. Fill the larger zipper baggie with 750 mL (3 cups of ice). Measure 60 mL (1/4 cup) of salt and sprinkle it over the ice. 3. Place the smaller zipper bag into the larger one and close tightly. 4. SHAKE, SHAKE and SHAKE some more! 5. Be patient, it will take a little while, but you will have a delicious frozen drink in no time at all. 6. Carefully remove the smaller bag from the ice mixture, rinse off and pour into a clean glass, add a straw. Enjoy! What is going on? The same reason many cities use salt on icy roads in the winter is why we are using salt with the ice to make a delicious frozen treat in this experiment. When the salt and ice mix, the freezing point of the ice is lowered causing the ice to melt. Where is the heat coming from to cause the ice to melt? Well, the heat that causes the ice to melt in this case is from the warmer juice in the other zipper baggie. This is why you have to keep shaking and shaking and shaking the baggie. By shaking the mixture up, you are continually moving the warmer juice mixture from the middle of the zipper baggie to the outside where it can begin to freeze evenly. By lowering the temperature that the ice freezes in our container, we are able to create temperatures below 0 C which is necessary for the juice to freeze into delicious frozen slushy treat. If you have an interest in science and want to learn more about Praxis please join us at our AGM Aug. 22 at Paradise Valley Golf Course. The meeting starts at 7 p.m.. I hope to see you there Patty Rooks is senior scientific consultant at 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. 23-22
