Required Practical 2: Thermal Insulation

Aim

Comparing the effectiveness of different materials as thermal insulators

Outline the basic steps of the practical.

1\. Wrap glass beakers with different insulating materials

2\. Boil water in a kettle and pour into the beakers

3\. Record the initial temperature of the water in each beaker

4\. Record how the temperature changes every few minutes

Give examples of materials which you could test the insulation properties for using this method.

● Newspaper

● Corrugated cardboard

● Bubble wrap

● Polystyrene

● Cotton wool

● Tin foil

Method

1. First place a small beaker inside a larger beaker
2. Use a kettle to boil water
3. Transfer 80cm^3 of hot water into the small beacker
4. Use a piece of carbord as a lid for the large beaker, the lid must have a hole for the thermometer
5. Place a thermometer through the hole into the cardboard lid- The bulb of the thermometer must be in the hot water
6. Record the starting temperature of the water and start a stopwatch
7. At this point, record the temperature of the water every 3 minutes for 15 minutes
8. Repeat the experiment using the same volume of hot water
9. use insulating material to fill gap between two beakers
10. Use a range of different insulating materials
11. Use the same mass of insulating material

IV

Type of insulating material

Dv

Temperature

Cv

Volume of water

Mass of insulating material

Starting temperature of the water

How can you secure the materials once wrapped around the beaker?

Using rubber bands.

Why do you leave one beaker with no insulation wrapped around it?

To act as a control beaker. It can be used to compare the temperature drop of the water with and without insulation.

As well as wrapping the beaker with the insulation, what else should you do to insulate it?

Cut out a circle for the lid of the beaker to reduce heat loss from the top. The lid should have a small hole for the thermometer to fit into.

How can you compare the effectiveness of the different insulators?

Compare the temperature change that has occured over a fixed interval of time. The smaller the temperature change, the more effective the insulator is.

Graph

Plot cooling curves

The water will cool down most slowly the most effective the insulating material

As well as the effectiveness of different types of insulators, what else can you test using this method?

The effectiveness of different thicknesses of the same insulator.

Aim 2

Thickness of material effects thermal imsukatin

Method 2

1. Start with a beaker contains 80cm^3 of hot water
2. Measure the temperature of every three minutes for 15 minutes
3. Repeat the experiment but this time we wrap two layers of the paper around the beaker
4. Repeat experiment 4 more tiles using 4 layers , then 6 layers

Iv

Number of layers of paper

Dv

Temperature

Cv

Starting temperature of water

Volume of water

Conclusion

More layers of paper the slower the water cools down

Because more layers is a more effective thermal insulator than fewer layers

What safety precautions should be taken when carrying out this experiment?

● Avoid touching the beaker after heating

● Place on a heatproof mat when hot

● Take care when pouring boiling water to avoid scolding

● If a beaker cracks, avoid using it and inform a technician