Thermos Lab

In this lab, we made a thermos out of materials brought from home, which will keep heat while holding 250 ml for 2o minutes.

HYPOTHESIS: If we put boiling water in our thermos, then, after 20 min., it would have cooled down 5 degrees because the materials would have kept the majority of the heat from escaping.

VARIABLES:

Independent: Materials

Dependent: Temperature of water inside the can

Controlled: Amount of water, size of the can, size of material, temperature of environment, time recorded

Control: A real thermos

MATERIALS:

-2 sheets of Metallic paper

-4 sheets of Aluminum foil

-7 pieces of wood

-2 sheets of paper

-2 sheets of plastic paper

-1 Can (thermos)

-150ml of boiling water

-Glue guns (to glue on the wood)

-Tape (to stick materials on the can)

METHOD:

1. Cut the wood into 7 pieces of 3cm.

2. Surround the can with the materials tightly in the following order (the first material listed should be placed directly on the can): wood (must be glued onto can), paper, plastic paper, metallic paper, tin foil

3. Pour the boiling water into the can.

4. Fill in row in the data table reading “0:00”

1. Every 2 minutes, write the temperature down on the data table and record observations. Stop when the time has reached 20 minutes.

OBSERVATIONS (Results):

OUR THERMOS:

Time (min.)	Temperature (centigram)	Observations
0:00	73
2:00	71	The outside of the thermos is relatively warm
4:00	69	Outside of the thermos is steadily getting hotter
6:00	67.5
8:00	66
10:00	65	Outside of the thermos is noticeably hotter than before
12:00	63.5	Table which thermos is placed is hot - conduction
14:00	63
16:00	62
18:00	62
20:00	61

CONTROL:

Time (min.)	Temperature (centigram)	Observations
0:00	73	Steaming, outside is cool
2:00	72
4:00	70	Outside of the thermos is staying the same temperature
6:00	68
8:00	67
10:00	66
12:00	65.5	Table which thermos is placed is cool
14:00	64.5
16:00	64
18:00	63
20:00	63

GRAPH:

DATA ANALYSIS:

From the graph, it is evident that the control, a real thermos, works better than the thermos that we had made. Both of the thermoses started at 73〫C, however, the control was 63〫C after 20 min., while our thermos was at 61〫C. This means, our thermos was 2〫C colder than the control - although, that is not a big difference.

CONCLUSION:

Our hypothesis was incorrect. Although the majority of the heat the water contained was kept in the thermos as we had thought, our thermos had cooled down 13 degrees centigram in the space of 20 min. Before we had thought it would cool down 5 degrees centigram. Our thermos did somewhat work, however. The results were very alike to the control’s results. The reason for why the thermos worked was because the materials that were attached to the can acted as insulators. Insulators are objects that don’t let heat pass through them easily. These were needed for the thermos to work because, without these insulators, the heat of the water would escape to the outside of the can. This would happen because the heat of the water would travel to the insides of the can, and then to the outside - or in other words, conduction. However the insulators stop this from happening. Knowing that wood and paper were good insulators, we put these materials on the can first. I think one of the reasons the water lost 13 degrees was because we added tin foil to the thermos. This was because tin foil, made of metal, is known as a good conductor, which isn’t suitable for a thermos, as they let heat pass through them quickly. This happens because the free electrons cause all the other atoms to vibrate more rapidly because they often collide with each other. As they vibrate more and more they bump into their neighbors, then their neighbors vibrate more, and so on - like dominoes! However, when we were building the thermos, we decided to include the tin foil because we thought that the more layers we included, the better the thermos would be. However, I think the thermos would be more efficient if we had added styrofoam or other good insulators instead.