Conduction, Convection and radiation. Conduction is the passing of heat along a medium to neighboring part with no visible motion accompanying the transfer of heat- for example, when the whole length of a metal rod is heated but only one end is held in the fire
Convection is the transmission of heat through a fluid(liquid or gas) in currents- for example when the air in a room is warmed by a fire or radiation.
Radiation is the heat transfer by infrared rays. It can pass through a vacuum, travels at the same speed as light, can be reflected and refracted and does not effect the medium through which it passes. For example- heat reaches the Earth from the Sun by radiation.
This is very similar to some of the definitions on the first page but it has gone in to more detail about what heat is and what effects it. For example, the definition of the infrared did not say that it was effected by reflection and refraction. This means it will be effected by different colour materials especially; black(it will absorb the heat), white(will not absorb the heat, will reflect heat to some extent) and silver(as it will reflect the heat back). Still air is also a good insulator as it traps the heat particles.
I am going to find out which substance is the best insulator. I will do this by testing different types of substances to see which one keeps in the most heat. I can do this by filling beakers wrapped in the different substances with hot water, then after a period of time the one with the hottest water has got to be the best insulator.
Diagram Apparatus I Will Need:
* Thermometer to take the temperature but it can also be used to stir before the temperature is taken to reduce convection.
* Glass beakers(18 for the main experiment), glass is a good insulator.
* Heat proof mat to stop heat escaping.
* Water
* Insulating materials.
* Measuring cylinder to measure out water (150ml)
* Stop clock
* Lid to reduce conduction
Method For Preliminary Experiment.
I am going to use different materials and test which one is the best insulator. The range of materials I am going to test are:-Silver foil, black paper, J-cloth, bubble wrap, rock wool and a control (glass beaker with no insulating). This means I am going to be testing 5 insulated beakers and 1 that is not insulated. For this experiment I will cover 5 beakers, each beaker will have a different insulating material wrapped around the side of it(only the side will be covered ). I will then place a lid with a hole in it on top of the beaker and the beaker will be placed on top of a heat proof mat. This should help prevent heat being lost from any other part of the beaker, except the side this will allow me to get an accurate reading of how effective the material is at insulation.
To do the experiment I must put 150 ml of hot water into all of the beakers, I will then cover the beaker with a lid and place the beakers onto a heat proof mat. Then every 2 minutes for 20 minutes I will stir the water and take its temperature.
The range of materials I will use is j-cloth, black paper, bubble wrap, silver foil and I will also do a control so I can compare the results I get from the insulated beakers to a non-insulated beaker.
To Keep My Investigation Fair:-
I will keep all of the independent variables the same. Here is a list of the independent variables that I will keep the same:-
* The amount of hot water I use.
* The time as my results would be inaccurate if they were done for different periods of time.
* The amount of material I use to insulate the beaker as my results would not be accurate if one beaker was more insulated than all of the others.
* I will stir the water before temperature is taken so the result has not been effected by convection.
The dependent variable that I have no control over is the temperature of the water as it may have cooled and be at different temperatures before the experiment has even started.
To Keep My Experiment Safe:-
* I will clean up any water spillage’s so there is no risk of slipping.
* I will also be careful not to spill any of the hot water on myself, my class mates or the floor.
Prediction
I predict that this will be the order in which they insulate, best to worst.
1. Bubble wrap will be the best insulator as has bubbles of still air that will trap the heat.
2. Rock wool as it is made out of lots of fibre’s that will have trapped air particles in-between them, so this will trap the heat.
3. Silver foil as it will reflect the heat back in to the beaker( stops infrared radiation).
4. J-cloth as it will have some trapped air, it is a thin material and does not have that many fibre’s and does not reflect or absorb much heat.
5. The control as it is not insulated it is there so I can compare the insulated beakers with a non-insulated beaker. But glass its self is a good insulator.
6. Black paper will have the worst temperature as it is an emitter of heat so will loose heat but the colour will also absorb and trap some of the escaping heat ( absorbs the heat from infrared radiation).
Preliminary Results Table
Temperature of Water in Each Beaker
Insulating
Time in Minutes
Material
0
2
4
6
8
10
12
14
16
18
20
J-cloth
50
48
47
46
44
43
42
42
41
41
41
Rock wool
50
48
48
46
45
45
45
44
44
42
41
Silver foil
50
48
48
46
44
42
42
41
40
39
38
Black paper
50
46
45
44
43
41
40
39
38
37
36
Bubble wrap
50
48
46
45
44
44
44
43
42
41
40
Control
50
47
46
44
42
42
41
40
39
38
37
My preliminary results show that the rock wool and the j-cloth were the best insulators because after 20 minutes the water in their beakers was 41 C , higher than all of the other beaker’s water that were wrapped in other insulating material.
For my main experiment I will keep the range of materials I used the same. I will increase the length of time my experiment runs for by 10 minutes as I believe this will give me a better range of times and increase the accuracy, as the longer the period of time the beakers are left to cool for the easier it is to see how effective each insulator is. I will still only cover the side of the beaker as I believe this is where most of the heat is lost from.
I will repeat the experiment 3 times as I believe this number of results will give me an accurate average. I will not include any results that I believe to be wrong in my average.
Method For Main Experiment
The method for my main experiment will be the same as the method for my preliminary experiment except I am going to keep increase the amount of time by 10 minutes as I believe this will be the best amount of time to get an accurate reading. I will do my main experiment results to one decimal place as I believe that this will give me the most precise results .When reading the temperature of the water from the thermometer I will take any number that is whole e.g. 24 to be 24.0 as I believe that this will improve my accuracy. To improve my reliability I will repeat each material three times as I believe this will give me a reliable average.
Results Table For My Main Experiment
Any number that are written in yellow are inaccurate and have not been included in my average.
Temperature of The Water In Each Beaker ( C)
Type of
Test Number
Time When Each Temperature Was Taken (minutes)
Material
And Average
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
J-cloth
Test 1
55
51
51
49
48
46
46
45
45
44
43
42
42
40
40
40
Test 2
55
50
48
47
46
45
43
43
43
42
41
41
40
39
39
39
Test 3
55
49
48
46
46
44
43
43
42
41
40
39
37
36
36
35
Average
55
50
49
47.3
46.6
45
44
43.6
43.3
42.3
41.3
40.6
39.6
38.3
38.3
38
Rock wool
Test 1
55
52
50
49
48
47
46
45
44
44
43
42
41
41
40
39
Test 2
55
51
49
48
47
46
46
45
44
43
42
41
41
40
40
39
Test 3
55
54
50
50
48
47
46
45
45
43
42
42
42
41
41
40
Average
55
51.5
49.6
49
47.6
46.6
46
45
44.6
43.3
42.3
41.6
41.3
40.6
40.3
39.3
Silver foil
Test 1
55
51
49
45
44
43
42
40
39
39
39
38
38
37
37
36
Test 2
55
52
50
48
47
45
44
43
42
41
40
38
38
37
36
36
Test 3
55
52
48
48
46
45
44
42
41
41
40
39
39
38
38
37
Average
55
51.6
49
48
45.6
44.3
43.3
41.6
40.6
40.3
39.6
38.3
38.3
37.3
37
36.3
Black paper
Test 1
55
50
47
45
44
42
40
39
39
38
38
37
37
36
35
35
Test 2
55
51
49
47
46
43
41
41
40
40
38
38
37
37
36
35
Test 3
55
51
48
46
46
43
41
40
40
39
38
37
37
35
34
34
Average
55
50.6
48
46
45.3
42.6
40.6
40
39.6
39
38
37.3
37
36
35
34.6
Bubble wrap
Test 1
55
53
51
49
48
47
46
46
45
44
43
41
40
39
38
37
Test 2
55
52
52
50
49
47
47
47
47
46
45
43
42
41
40
39
Test 3
55
51
49
47
46
45
45
44
44
43
42
41
41
40
39
37
Average
55
52
50.6
48.6
47.6
46.3
46
45.6
45.3
44.3
43.3
41.6
41
40
39
37.6
Control
Test 1
55
52
50
48
47
45
44
43
42
41
40
39
38
37
37
36
Test 2
55
51
50
48
47
46
45
44
43
42
41
40
39
37
35
34
Test 3
55
49
48
47
46
44
42
41
40
39
38
38
37
37
35
35
Average
55
50.6
49.3
47.6
46.6
45
43.6
42.6
41.6
40.6
39.6
39
38
37
35.6
35
My results show that the rock wool and the j-cloth are the best insulators as they had the hottest water after 30 minutes. To prove this my table of results shows that the finishing temperature was higher than the other insulators. The rock wool (which is a fiber glass substitute) was the best because it is a thick layer of fibres and contains pockets of still air. Still air is a good insulator because the convection currents are not able to be generated because the air molecules remain still.
The j-cloth was also the second best insulator as it had the second highest water temperature. J-cloth was a good insulator because it has a net like structure which traps air particles. The structure of the j-cloth is good for insulating as it traps escaping heat particles. But if the j-cloth gets wet the air particles are knocked out. Water is a good conductor so the heat is lost through the wet j-cloth easily, if the j-cloth absorbs water it will evaporate and take some of the heat with it.
The worst insulator was the black paper as it is an emitter of heat not a reflector of heat so it absorbs the infrared radiation. This means that heat can be lost easily. But the black paper is also a bad conductor so this would reduce some of the heat loss. The black paper is a bad insulator because it is made of paper, paper has a dense particle structure so it is harder for the conduction currents to run through it. Also because of its tight particle structure few heat particles are trapped.
Conclusion
I have found out that the more air particles there are trapped in fiber or net like material the hotter the water stays as the heat particles get trapped between the materials fibers with still air. I have found out that rock wool is the best insulator, j-cloth is the second best, then bubble wrap, then silver foil, then control and then the black paper. I conclude that rock wool was the best insulator you can see this on my graph, my graph shows that out of all the other materials I tested , rock wool kept the water the hottest. You can see this on my graph as the rock wool has got the steepest slope. I believe that conduction may have effected my results as the hot particles were rising to the top of the beaker even when we were taking the temperature. I could have continuously stirred the water while I took the temperature.
My graph shows that all of the materials had a very close temperature range, at 30 minutes the difference in temperature between the rock wool and the black paper was only 4.7 C.
I predicted that the bubble wrap would have kept the water the hottest because it is made up of many pockets of still air and that the black paper would have the lowest temperature because it would emit the heat not reflect it back into the beaker.
The order in which I predicted the materials would be in is wrong except for the last two as I said it would go control, black paper. I believe my reasons for putting them in that order are accurate even if I did not get them in the correct order.
In my opinion the bubble wrap should have kept the water the warmest as the particles of still air should have trapped heat particle and reduced any convection as the air particles would not move so the heat would not have been able to move. But I believe that my results are very accurate as most of my temperatures only had a difference of 2 C between them this has made the averages very accurate.
Evaluation
I believe my results are quite accurate and would be considered reliable as non of my results have a big difference in temperature. I have highlighted the results that I believe are wrong on my results table and have not included them in my averages. On my graph my points go up in curves or in some sort of curve. I have joined all of the points on my graph together but on some of my curves I have done a curve of best fit, I have done this because it will show me if any results are slightly wrong.
The trend I see from the graph is that the more trapped air particles or the denser the material the steeper the slope of the graph is. I believe that the way in which I carried out my experiment was good as I followed my method exactly. To improve the accuracy of my method I could have said I would use a ruler to get a more accurate measure of each substance, I could make sure that the materials all had the same surface area because the bigger surface area the more heat molecules it could have trapped. I could have also make sure that the room was the same temperature for each experiment because if the room was hot for one experiment and cold for another then the results would be inaccurate as the molecules would be hotter or colder and this could effect the fall in temperatures.
The results I have support my conclusion and my prediction, as what I predicted would happen did happen. The order of the concentrations for the most gas released in 5 minutes was also accurate, as it was in the order that I predicted.
To extend my investigation I could test if the temperature had any effect on the amount of gas released, I believe this would provide me with the relevant information about what the optimum temperature is for a reaction to take place. I could then test the optimum concentration and the optimum temperature together and see how much gas is released in 5 minutes and compare it to the separate results of the concentration and temperature.
