Thermal insulation

• Summary - Part 1:

  In this part of the experiment you will measure the rate of cooling of a beaker of hot water when insulated with different materials, to determine which is the best thermal insulator.
• Equipment - Part 1:

  large beaker (eg 800 ml)

  • small beaker (e.g. 250 ml)

  • thermometer

  • kettle to heat water

  • piece of cardboard

  • scissors

  • stopwatch

  • selection of insulating materials, eg polystyrene granules, sawdust, bubble wrap, newspaper
• Risk Assessment - Part 1:

  Take great care when pouring the near-boiling water from the kettle. If you splash any on yourself, immediately wash the affected area with cold water.
• Step 1:

  Use the kettle to boil water and then put 80 ml of this hot water into a 100 ml beaker. Place the small 100 ml beaker inside the large beaker.
• Step 2:

  Use a piece of cardboard, with a hole for the thermometer, as a lid for the large beaker. Insert the thermometer through the hole in the cardboard lid so that its bulb is in the hot water.
• Step 3:

  Record the temperature of the water and start the stopwatch. Record the temperature of the water every 5 minutes for 20 minutes.
• Step 4:

  Repeat steps 1 to 6, but this time fill the space between the small and the large beaker with an insulating material. Make sure that you use the same volume of water each time. Draw cooling curve graphs by plotting temperature against time for each insulator, and determine which is the best insulator.
• Summary - Part 2:

  In this part of the experiment you will measure the rate of cooling of a beaker of hot water when insulated with different thicknesses of the same materials, to determine factors that may affect thermal insulation properties of a material.
• Equipment - Part 2:

  beaker (eg 250 ml)

  • thermometer

  • kettle to heat water

  • piece of cardboard

  • scissors

  • stopwatch

  • insulating material, eg newspaper, corrugated cardboard, bubble wrap • rubber bands
• Risk Assessment - Part 2:

  Take great care when pouring the near-boiling water from the kettle. If you splash any on yourself, immediately wash the affected area with cold water.
• Step 1:

  Use the kettle to boil water and then put 200 ml of this hot water into a 250 ml beaker. Use a piece of cardboard, with a hole for the thermometer, as a lid for the beaker.
• Step 2:

  Insert the thermometer through the hole in the cardboard lid so that its bulb is in the hot water. Record the temperature of the water and start the stopwatch.
• Step 3:

  Record the temperature of the water every 5 minutes for 20 minutes. Repeat steps 1 to 5, but this time insulate the beaker by wrapping one or more layers of insulating material around the beaker. The insulating material may be held in place by using rubber bands. Make sure that you use the same volume of water each time.
• Step 4:

  Draw cooling curve graphs by plotting temperature against time for each number of different layers of insulation. From your graphs, write a conclusion about the effect of changing the number of layers of insulation.