The materials I decided to investigate in this inquiry included aluminum foil, paper towel and newspaper. The mugs were large and only half filled with the hot water. A large portion of the heat was expected to be transferred from the water to the mug. Based on my knowledge of the specific heat of substances; I predicted that the aluminum foil would keep the substance warmer while the paper towel would not keep the water in the mug warm because of its porous surface.
The greatest challenge I experience was locating another thermometer. The course thermometer was damaged during shipping and as a result I had to rely on a kitchen thermometer normally used for testing internal meat temperatures. Due to the design of the thermometer, its accuracy was limited but it did reveal that the mug insulated with the aluminum foil had remained the warmest (130oF). The second warmest was the mug insulated with the paper towel (120oF) while the third warmest was the mug insulated with the newspaper (110oF). The control mug which did not have a lid cooled to 90oF. The exterior of the mugs all felt similar in temperature while the lids themselves varied in temperature. The results were due to the specific heat of the selected substances and the porcelain mugs.
The results obtained helped explained why the travel mugs which are designed to keep liquids warm are often constructed of stainless steel. The stainless steel takes a large amount of time to absorb heat which in turn is released back into the liquid which keeps it warm longer. I believe that the paper towel may have kept the liquid warmer than the newspaper because of the insulating capacity of air. The paper towel surface was porous which trapped air. As this air warmed it created an insulating barrier which helped trap the heat inside the mug. The newspaper cover became saturated with water vapour (phase change) which would have contributed to heat lost.
I think students would enjoy this experiment if I could relate it to items they consume like hot dogs or pizza. Pizza has a tendency to remain hot longer because the heat of the sauce is trapped by the cheese layer (insulator). By testing three pizzas (one with sprinkled cheese, one without cheese and one with thick layer of cheese slices, we could investigate the insulating properties of cheese. The pizzas could be removed from the oven and the sauce temperatures regularly measured to see which ones cools the fastest (worst insulator) or slowest (best insulator).
I bet everyone of my grade 8 students would be engaged (and hungry) during the lesson.
Your kids would love to complete this experiment with pizza!
ReplyDeleteYour results varied a lot more than mine. I used foil, paper towel, newspaper, and plastic wrap as insulators on top of each mug. My results were within two degrees Celsius of each other. I did not leave a control, but now I'm thinking that I probably should have. Interesting post!
It was interesting to see your results with the control sample. I did not have a sample without a cover but wondered what the temperature would have been without one. Testing pizza would be interesting, I may have to try that with my kids over the summer. Good idea!
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