Exploring Heat Transfer

Setting up the activity for this week’s application required various techniques in order to obtain reliable data. The activity’s procedure is to obtain 4 mugs and pour hot water into each one, then select various materials to cover the mugs and after thirty minutes check the temperature and see which material makes the best insulator. The first step was to achieve the following constants (variable

s): 1) 4 identical mugs made out of glass, 2) mark each mug at the same measurement as to have the same amount of hot water poured in each mug, and 3) maintain the temperature of the hot water in all 4 mugs at the same degree before covering with the selected materials. I had to obtain a more reliable thermometer than the one provided in the science kit. Finally, I selected the 4 materials I would use to cover each mug: aluminum foil, ceramic, glass, and plastic.

First inquiry question would be: what material will make the best insulator? After adding the hot water into the 4 mugs, I quickly covered each mug with on of the selected materials and waited thirty minutes to read the temperature of the water. My hypothesis based on prior knowledge would be that the aluminum foil would maintain the heat better than the others. I personally use stainless steel mugs to carry my hot coffee on my way to work. I relate the stainless steel mug to the aluminum foil cover I will put around one of the mugs. I believe as stainless steel makes excellent insulators, aluminum will also do the same being a metal.

After thirty minutes, the temperature of the hot water was higher in the mug covered with aluminum foil, then followed the mug with the hard plastic cover, then the one with the glass cover, and finally the one with the least heat retention was the mug with the ceramic cover. Aluminum foil proved to be the best insulator as expected
When aluminum foil was rapped around the mug, pockets of air were trapped. It is proven that trapped air acts as an insulator against conduction and convection (Tillery, Enger, & Ross, 2008). This is one reason it was a good insulator, but the main reason is that aluminum reduces heat transfer produced by radiation and reflects the radiation back into the hot water. Thermal radiation is reflected rather than absorbed. Remembering always that aluminum foil is also a heat energy conductor. This could set the stage for inquiry questions like the following: if all the covered mugs had air trapped in them, why was the aluminum foil the best insulator? or what properties of the aluminum foil help it be the best insulator among these selected materials?
References:
Tillery, B. W., Enger, E. D., & Ross, F. C. (2008). Integrated science (4th ed.). New York: McGraw-Hill.