specific heat capacity

• Energy transmission


  Conduction, convection or radiation
• Conductivity of materials


  Time taken to transmit energy through them
• When materials are heated, the molecules gain kinetic energy and start moving faster
• Temperature


  Measure of the average kinetic energy of the molecules
• Different materials require different amounts of energy to change temperature
• Specific heat capacity


  The amount of energy needed to raise the temperature of 1 kg of substance by 1°C
• Specific heat capacity of materials

  • Water: 4,200 J/kg°C
  • Brick: 840 J/kg°C
  • Copper: 385 J/kg°C
  • Lead: 129 J/kg°C
• Lead


  Warms up and cools down fastest because it doesn't take much energy to change its temperature
• Brick


  Takes much longer to heat up and cool down, used in storage heaters to stay warm for a long time
• Most heaters


  Filled with oil (1,800 J/kg°C) or water (4,200 J/kg°C) as these emit a lot of energy as they cool down and stay warm for a long time
• Energy is transmitted by conduction, convection or radiation
• The conductivity of materials can be compared by examining the time taken to transmit energy through them
• There are different ways to investigate methods of insulation
• Practical activity to measure specific heat capacity

  1. Make and record potential difference, current and time accurately

  2. Measure and observe the change in temperature and energy transferred

  3. Use appropriate apparatus and methods
• Potential difference (or voltage)


  Measure of the energy given to the charge carriers in a circuit. Units = volts (V). This is the voltage between two points that makes an electric current flow between them.
• The aim of the experiment is to measure the specific heat capacity of a sample of material
• Method to measure specific heat capacity

  1. Place immersion heater into block

  2. Place thermometer into block and add oil

  3. Fully insulate block with cotton wool

  4. Record initial temperature

  5. Connect heater to power supply for 10 minutes

  6. Record highest final temperature reached
• The block has a mass of 1 kg and the heater was running for 10 minutes = 600 seconds
• The actual value for the specific heat capacity of aluminium is 900 J/kg°C
• The calculated value does not match exactly but it is in the correct order of magnitude
• Experiments are subject to some amount of experimental error due to inaccurate measurement, or variables that cannot be controlled
• Not all of the heat from the immersion heater will be heating up the aluminium block, some will be lost to the surroundings
• More energy has been transferred than is needed for the block alone as some is transferred to the surroundings
• This causes the calculated specific heat capacity to be higher than for 1 kg of aluminium alone