Purpose: The purpose of this experiment is to find out the best thermal insulator. A thermal insulator is a material that doesn’t conduct heat (or doesn’t conduct as much heat), viz. poor conductors. With that, thermal insulators don’t let heat pass through them.
Question: What is the best insulator?
Hypothesis:
If it is a better insulator (a worse conductor), the water will lose less heat (keep more heat) and the change in temperature will not be as much. It is because insulators doesn’t absorb heat so they keep it in.
If aluminium foil is the best insulator, the change in the water temperature will be less. It is because insulators keep in (or out) heat, so not much heat goes away; Insulators keep in heat because they cannot conduct heat or cannot conduct much heat; Aluminium foil is a good insulator because it has a light coloured and shiny surface that reflects thermal radiation which is infrared radiation.
Variables:
Independent variable: Type of material
Dependant variable: Temperature of the water
Constants: cup, amount of water, amount of time
Control: Do it once with no insulator
Materials: a styrofoam cup, insulators, thermometer, A few cups of hot water, timer, notes
Procedure:
- Boil some water and pour about 2 cups (cups as measurement) into the styrofoam cup.
- Put a lab thermometer in the water
- Make a small hole in your type of material you are using as an insulator. Put the thermometer through the hole and push your insulator down to cover the cup with it. You can use tape or rubber band to make sure the cup is sealed so the hot air doesn’t come out and affect the results.
- Wait until the thermometer shows the highest temperature and record it. And then start timing immediately.
- Write down the temperature every minute. Do it until the 30th minute and then stop.
Observation:
No matter using aluminium foil or wool cloth, the temperature decrease for about one degree celsius per minute, although sometimes the temperature of the water goes down more or less.
Results:
Aluminium Foil
Time Temperature (degrees celsius)
0 81
1 79
2 76
3 74
4 72.5
5 71.5
6 71
7 69.5
8 68
9 67
10 66
11 65
12 64
13 63
14 62
15 61
16 60.5
17 60
18 59
19 58
20 57
21 56.5
22 55.5
23 55
24 54.5
25 54
26 53
27 52.5
28 52
29 51
30 50
The difference between starting and the ending temperature: Aluminium foil- 31ºC
Wool cloth
Time Temperature (degrees celsius)
0 83
1 79.5
2 77
3 75.5
4 73.5
5 72
6 70.5
7 69
8 68
9 66.5
10 65
11 64
12 63
13 62
14 61
15 60
16 59
17 58
18 57
19 56
20 55.5
21 54.5
22 54
23 53
24 52.5
25 52
26 51
27 50.5
28 50
29 49
30 48.5
The difference between starting and the ending temperature: Wool cloth- 34.5ºC.
The graph below shows the data of both insulators I used- both wool cloth and aluminium foil. It also shows the comparison of the two observations for using aluminium foil and wool cloth as the thermal insulating cover.
In the above line graph,
Green is representing wool cloth,
Red is representing aluminium foil.
For wool cloth, the temperature of the water decrease faster, and then it starts to keep in the heat, and the temperature decreased slower.
For aluminium foil, the temperature went down quite quick at first, but then it slowed down and the temperature decrease became steady.
If the time is divided into three parts: 1st part, wool cloth loose temperature quicker; 2nd part, both the cup of the two materials have the same temperature decrease; 3rd part, wool cloth loose temperature quicker again.
The below graph shows the change in temperature of the whole grade:
Change in Temperature of Different Groups Using Different Materials- Whole Grade
The materials used for each group:
- Control- None
- Royce Mushroom- Royce Chocolate Cooling Bags (2), Tin Can (Metal Can), Polyester
- Coat- 1 Winter Coat, 5 Napkins, 1 Tin foil, 1 Hoodie, 1 Cotton
- Sarrah’s Love- Tin Foil, Polyester, Foam, Plastic Box
- The Young Scientist- Aluminium Foil
- The Young Scientist- Bubble Wrap
- Hat- Hat, Aluminum (and hands)
- Unicorn Three Skin- Aluminium, tape
- Cream Puff 0 Some- Wool cloth
- Cream Puff 0 Some- Aluminium Foil
- Snoopies- Jacket, sand, cotton, tin foil, Plastic bags, plastic tiny, tape.
- Chicken Mcnuggets- Wrapped with tin foil covered with 2 computer mouse pads
- and 3 computer cover with tape holding them together. Then covered it with a jacket, toilet paper and lastly, a towel which was used to cover the tinfoil.
- Snowy-Oceanz- Styrofoam Cup, Tin Foil and Packing Tape.
- Little Purple Ponies- Wrapped in cotton covered in paper shreds and taped with electrical tape. Then covered in more normal packing tape, the top was covered in aluminium foil. And the final layer was covered in a lot of toilet paper.
The more materials are used to cover up the cup, the temperature decrease is slower. Which means, it can keep in more heat when there are many layers of materials.
Conclusion:
The results of my group shows that aluminium foil is a better thermal insulator. The reason behind is that aluminium foil reflects radiation because its surface is shiny and bright-coloured (silver). When the cup is sealed (or when aluminium foil is wrapped around) and it reflects radiation, the radiation has nowhere to go. The radiation will keep bouncing back and forth in the cup.
The results of the whole grade shows that: the more layers of materials are used to cover up the cup, the better the insulation. And for the best group of materials, apart from having many layers, it also has aluminium foil. The answer to “what is the best insulator”, is more layers of materials (thick layer), and aluminium foil, and poor conductors like tissue and tape. More layers insulate heat more. It is because with more layers, the thickness increases and air pockets form (air is not good conductor as its particles are far apart). Therefore, it creates a longer path for the heat to come out through conduction, and with more layers, the hot air inside comes out more hardly. All makes less heat-loss. Convection doesn’t affect the results because the cup is well-sealed. Radiation cannot come out because there is aluminium foil. Aluminium foil is a good thermal insulator as it reflects radiation with its shiny and bright-coloured surface.
My hypothesis is partly correct.
Evaluation:
We didn’t do the control, so we used the other classes which might be a little different due to the environment and condition. Also, when we started, we started timing a little bit late, and it was quite messy. However, we then managed it. I think the experiment was controlled. We used a timer and check the temperatures at the right time. We check the temperatures carefully. We made sure that the cup was sealed. The amount of water is the same. The amount of time was the same. We used the same brand of cup. We measured the difference instead of the ending temperature so it wouldn’t be affected by the starting temperature.
Although it is good, to make it better, I think we can do it a few times and take the average of the temperature difference, so if anything happened we will noticed.
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