Nov. 19-21

Last weekend, I added the finishing touches to my thermos to test it in an in-class competition. The competition's objective was to retain the most amount of energy and to have the least temperature change.

The previous weekend, I reflected on what materials to use for the thermos in order to retain the most amount of energy. As I was thinking, I thought that insulators would be the best materials to use. Essentially, an insulator traps energy in for longer periods of time, so it takes longer to heat up and to let energy go.

Thinking about this, I decided to use a Styrofoam box as the outermost layer of the thermos with insulation inside, and the materials included: Styrofoam and a Styrofoam cup, carpet insulation, duct tape, super glue, tin foil, peanut tin cans, and plastic wrap. Next, I used carpet insulation and tin foil since they have water vapor barriers, which lessened the temperature change and kept the energy in. Duct tape and super glue retained heat inside the thermos since they are good insulators and keep the thermos intact to prevent more energy from escaping. The cotton T-shirts and the plastic wrap were wrapped around the cylindrical thermos to reduce heat loss and retain the temperature of any liquid in the thermos longer. The peanut tin cans served as the outermost lining of the cylindrical thermos and soaked moisture from the insulation, and the peanut can lid was used as the inner lid to keep energy in longer.


Last weekend, I stuffed the Styrofoam box with carpet insulation, glued it down, and secured it with duct tape around the Styrofoam cup. First, though, I had to use a hand saw to saw off the bottoms of the tin can from the peanut tin cans, and then I cut the carpet insulation into 2-3 circles and used those as the base of the peanut tin cans. I then wrapped the Styrofoam cup with 8 layers of T-shirts and tin foil.

Next, I performed three tests: at 10ºC, 20ºC, and 30ºC. What I did was I used tap water and made sure the temperatures were correct. I then performed three trials at those three temperatures individually by pouring them in the Styrofoam cup. Then, I sealed the lid on the thermos and recorded the temperatures using the thermometer through a straw that went through the top of the Styrofoam box.

On Monday, the competition commenced. I tested the water at 80ºC (353.5 K) at 355 mL. My procedure was to get the water in the thermos as quickly as possible. So, I used tongs to lift the flask with the water in it and pour it into the thermos. However, I had to keep in mind that time was my worst enemy–if I didn't seal the thermos quickly, the temperature change could increase since more energy would be able to escape. Thus, I sealed the thermos quickly and only adjusted it when I saw it fit. However, I took out the straw that may have reduced heat loss had I not have removed it, which may have partially accounted for the 
increasing change in temperature.

For twenty minutes, I recorded the temperature change in the water. When it was time, it was 70.5ºC, thus a 9.5ºC change over the course of 20 minutes. I wasn't pleased with this, so I decided to make improvements on my thermos. I had a hunch that on Monday if I had 10 more minutes to test my thermos, the temperature would be around 60ºC. So, I wanted the temperature change to be reduced by at least 10ºC. So, on Monday night, I added insulation and super-glued it on the lid inside the thermos to reduce heat loss.

Then, I tested on Tuesday for 30 minutes with the water at 80ºC at a volume of 355 mL. This time, I didn't take the straw out so that the temperature change could be lessened. 

I felt less stressed about messing up on this lab–rather, I felt excited and confident that I could do well. So, I readily poured the water into the Styrofoam cup and then sealed the thermos without removing the straw. Next, I recorded the temperature from 80ºC to 72.5ºC, thus a 7.5ºC change. This was 2ºC higher than the temperature of the water after 20 minutes on Monday. I speculated that since the water's temperature on Monday after 30 minutes could be 60ºC, the temperature of the water on Tuesday after 30 minutes could possibly be a 12.5ºC change from Monday's possible temperature.

Although this speculation is possible, it is true that since Monday's results were less than that of Tuesday's–even during 20 minutes of Tuesday's lab–the results improved because more insulation was added to prevent less heat from running away.

During this week, while I was doing my lab, I finished up my presentation. I thought I did really well on it. On the presentation, I added information on the materials I used, and I gave a brief explanation for each and explained why they were used. I defined what a thermos was in the first slide to demonstrate its overall purpose, which is to retain energy and keep temperature constant. Next, I recorded information on the lab and the temperature changes from the pre-lab, Monday's lab, and Tuesday's Lab. I also made graphs for the data from the labs, and I added pictures of my thermos. I also updated it over the weekend to scientifically explain that on Tuesday, the temperature change was less than that of Monday's because I added carpet insulation on the lid of the thermos, which retained more energy in, thus lessening the change in temperature.