Insulators

Investigate the effectiveness of different materials as thermal insulators and the factors that may affect the thermal insulation properties of a material.

Students must investigate the effectiveness of various materials as thermal insulators, as well as look at how the number of layers of a specific material affects the insulating properties. A variety of materials could be included for students to test (for example: newspaper, aluminium foil, cotton). Students will use the rate of cooling water method to investigate this.

Equipment (per participant)

• Safety glasses
• 100ml beakers (x 5)
• 250ml beakers (x 5)
• Kettle
• Thermometer (x 5)
• Stopwatch
• Heatproof mat

• Square of cardboard with a hole in
• A selection of insulating materials
• Scissors
• Elastic bands

Method

Activity 1: Comparing the effectiveness of different materials as insulators to heat.

Students should place a 100ml beaker inside a 250ml beaker and boil a kettle.
They must carefully add 80mls of boiled water from the kettle to the 100ml beaker and cover the 250ml beaker with a cardboard lid.
A thermometer is inserted through the hole in the cardboard lid so that it sits in the water in the 100ml beaker. Students then record the starting temperature of the water and start the stopwatch. They must measure the temperature every 3 minutes over a 15 minute period and record in a suitable table.
The procedure is then repeated by adding the same amount of a different insulating materials between the two beakers, ensuring they use 80mls of water each time.
Students plot their results on a graph which will show a cooling curve for each material. Can students tell from their results which material was the best insulator and why do they think this might be

Activity 2: How the thickness of material affects the insulation of heat.

Students take a 100ml beaker and wrap the sides of the beaker in one insulating material (leaving the base of the beaker bare), using elastic bands to secure the wrapping.
They must now boil the kettle and carefully add 80mls of boiled water to the beaker. The 100ml beaker is covered with a cardboard lid and the thermometer is inserted
through the hole in the lid so that the thermometer sits in the water in the 100ml beaker.
Students record the starting temperature of the water and start the stopwatch. They must record the temperature of the water every 3 minutes over a 15-minute period in a suitable table.
The procedure is repeated, adding an increasing number of layers of the same insulating material to the beaker each time.
Students then use their results to plot a graph showing the cooling curve for each of the number of layers of insulation used.

Technician tips

• Care should always be taken when dispensing boiled water from the kettle.
• Lids for the beakers could be pre-made with a hole for the thermometer to save time and prevent thermometer breakages.
• Students should use the same ‘amount’ of insulating materials during the first activity to control this variable.
• This required practical could be split over a couple of laboratory sessions allowing for equipment cooling.