Student practical (Aiming for 4)

Name ...... Class ...... Date ......

Required practical 1: Measuring specific heat capacity

Specification reference:

  • P.1.1.3 Energy changes in systems
  • P.3.2.1 Internal energy
  • P.3.2.2 Temperature changes in a system and specific heat capacity
  • P.8.2.1 Required practical activity 1
  • MS 1a, 3c, 3d
  • WS 2.4, 2.6, 3.3

Aims

In this experiment, you will make measurements of energy transferred and temperature change and use these to find the specific heat capacity of aluminium.

Learning outcomes

After completing this practical, you should be able to:

  • take measurements to find the specific heat capacity of a substance
  • calculate the specific heat capacity of a substance
  • describe substances as being difficult or easy to heat up
  • list the factors that affect how much energy is needed to raise an object’s temperature.

Safety

  • Do not touch electrical equipment, plugs, or sockets with wet hands.
  • Do not touch the heater: it becomes very hot when in use, and can stay hot for a long time after it is switched off.
  • Switch the heater off if you think it is overheating.
  • Switch the heater off when you have finished using it.
  • When the thermometer is not being used, make sure it is placed where it cannot easily roll off the table.

Equipment and materials

  • 12 V, 24 W low-voltage heater
  • 12 V power supply for heater
  • joulemeter
  • two connecting leads
  • aluminium block with holes for a heater and a thermometer
  • insulation for block (including a thick insulating mat to place under it)
  • rubber bands or tape to fix insulation around block
  • thermometer

Setting the scene

Objects of the same mass but made of different substances need different amounts of energy to raise their temperature by the same amount.

Each substance has its own specific heat capacity, which tells us how much energy is needed to raise the temperature of 1 kg of that substance by 1°C.

The equation for calculating specific heat capacity from energy and temperature measurements is:

Method

1Check the mass of the aluminium block (it may be written on the block, or your teacher will be able to tell you).

2Wrap the insulation securely around the block, and place it on an insulating mat.

3With the power supply switched off, set up the apparatus as shown in the diagram.

4Check with your teacher that the joulemeter is correctly connected to the heater and the power supply.

5Place the thermometer in the aluminium block and measure the temperature of the block. Record this as the ‘starting temperature’ of the block.

6Switch the joulemeter on and record the ‘starting’ reading of the joulemeter.

7Switch the power supply on.

8Watch the reading on the thermometer, and when it reaches about 15°C above the starting temperature, switch off the power supply.

9Record the joulemeter reading and the thermometer reading.

10The thermometer reading might continue to increase for up to a few minutes after the heater has been switched off. Measure and record the highest reading of the thermometer after the heater was switched off.

Results

Mass of aluminium block in kg
Starting temperature of block in °C
Temperature when heater was switched off in °C
Highest temperature of block in °C
Starting reading on joulemeter in J
Final reading on joulemeter in J

Questions

1Complete the following paragraph by choosing the correct word or phrase from the underlined options.

While the heater is switched on, energy is transferred to / from the heater to/from the block by a force / heating. The temperature of the block decreases/increases. The amount of energy transferred is measured using the thermometer/joulemeter. The temperature change of the block is measured using the thermometer/joulemeter. (6 marks)

2You are going to use your results to calculate the specific heat capacity of aluminium. (4 marks)

energy transferred starting reading on joulemeter − final reading on joulemeter

 J− J

 J

temperature change highest temperature of block − startingtemperatureofblock

 C− C

C

C

3The true (accurate) value for the specific heat capacity of aluminium is 900 J/kg °C. Compare this with your experimental value. (1 mark)

4By comparing your result with the results of other groups, comment on the reproducibility of the result (how well different groups’ results agree with each other). (2 marks)

Student follow up

Different materials have different heat capacities. The heat capacities of three materials are given in the table below. You will need to use these in some of the questions below.

Substance / Water / Aluminium / Iron / Lead
Specific heat capacity in J/kg °C / 4200 / 900 / 390 / 130

1Aluminium’s specific heat capacity shows that 900 J of energy are needed to raise the temperature of 1 kg of aluminium by 1 °C.

aCompared with aluminium, is water harder or easier to heat up? Explain your answer.(2 marks)

bCompared with aluminium, is lead harder or easier to heat up? Explain your answer.(2 marks)

2In each of the pairs below, both blocks are going to be heated so that they change their temperatures as shown.

For each pair, circle which block needs more energy to heat it.

ablock A or block B(1 mark)

bblock A or block B(1 mark)

cblock A or block B(1 mark)

3In this question, calculate energies using the equation:

energy(J)mass(kg)×specificheatcapacity(J/kg °C)×temperaturechange(°C).

aCalculate how much energy is needed to raise the temperature of 1 kg of water by 5 °C.(3 marks)

bCalculate how much energy is needed to raise the temperature of 1 kg of lead by 5 °C.(2 marks)

© Oxford University Press 2016

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