Insulation is quite the opposite of conduction. It doesn’t have many free electrons to transfer the heat energy.
The question is that why are some materials conductors and some insulators?
The table below explains the answer.
From the above table we can see than insulators cannot conduct because in each mm there is only about one electron which is free to move. The rest of the electrons are firmly fixed to their atoms.
Prediction
To help me predict the best insulator, I used the table below of the insulation of houses as a guidance.
All the above figures are for a temperature difference across the surface of 20 C.
From the above I predict that in my experiment the best insulator would be carpet, then glass wool and then maybe wool or cotton. I predicted the above as these materials contain large amounts of trapped air, which help in making them good insulators.
Fair Test
To make this experiment fair, I will make sure the water, which is placed in the tub, is the same amount with the same temperature. I will also use the same tub throughout the experiment. I will wash the tub with cold water after each experiment and also immerse the thermometer in a beaker of cold water to gain accurate results the next time.
Safety Procedure
In this experiment to wear a laboratory coat is not really necessary, because you do not come into direct contact with acids or alkalis, but it would be better to wear one. Gloves should also be worn. Also to reduce risks I decided to use a kettle to heat the water in, instead of a bunsen burner. This would make it easier for me and will not be time consuming too.
Apparatus
- Beaker
- 20ml boiling water
- Kettle
- Thermometer
- Tub & lid
- Materials to test on
- Beaker of cold water
- Stopwatch
Diagram
Method
- Put water to warm in the kettle
- Fill the container with the material to be tested on
- Once the water is boiled fill 20 ml in a beaker and place it in the center of the container with the material all round it, close the tub
- Start the stopwatch
- Place the thermometer through the hole in the lid to check the initial temperature
- Keep recording the thermometer readings every 120 seconds up till 600 seconds. Note the difference in the initial and final temperatures
- Place the thermometer in a beaker of cold water after use
- Once the experiment is done wash the container and fill it again with some more of the same material
- Carry out the same procedure three times for each material following the same procedure.
Conclusion
I found that the carpet was the best insulator, thereafter loft insulation and thirdly cotton wool. I found that even after ten minutes the above three materials were quite warm.
The experiment went according to my prediction except that I thought each material would lose more heat than that which is stated.
I also noticed that the heat drops incredibly fast in the first few minutes and then the heat drops relatively slowly.
This experiment proves that these materials have very few free electrons and this is why the heat is not conducted but rather insulated, as energy spreads through them much more slowly.
Evaluation
Although my experiment proves that these materials have few free electrons thus making the insulators or poor conductors, I feel that my results are not quite reliable. This is because there was a hole in the lid, which may have affected my results as heat could have escaped from there. Also, I feel I should have used the same amount of each material, by weighing them, and then leaving each for the same amount of time, this would make my results more accurate.
If I were to do the experiment again I would also test on some conductors too, to compare the results. I would also keep the thermometer immersed in the water all the way through so I can see how the temperature drops.
The final temperature for knitting wool remained the same as the temperature at 480 seconds. I feel this was because I had used the same beaker of cold water throughout the experiment to cool the thermometer down and so the beaker of cold water may have become hot by the time I carried out the last experiment.
I could improve my results by experimenting on different types of each material, for example different carpets as I feel that the results would be different on each carpet, as their insulation properties would be different and so I would get a better average to compare against.