Paper 1 - Investigating Specific Heat Capacity - 21 Flashcards
what is the specific heat capacity of a substance
the amount of energy needed to raise the temperature of 1kg of a substance by 1°C
what are the units for specific heat capacity
J/kg°C
what equipment do you need for this experiment
7 points
1) power supply
2) heater
3) stop watch
4) thermometer
5) block of material
6) ammeter
7) insulating layer
how can you investigate the specific heat capacity of a solid material
6 points
1) you’ll need a block of the material with two holes in it for the heater and thermometer
2) measure the mass of the block and wrap it in an insulating layer, then put the thermometer and heater in the holes
3) measure the initial temp of the block and set the p.d of the power supply to be 10V, turn on the power supply and start the stop watch
4) as the block heats up use the thermometer to measure its temp every minute
5) keep an eye on the ammeter, the current through the circuit shouldn’t change
6) when you’ve collected about 10 readings turn off the power supply and do some calculations to find the specific heat capacity of the material
why do you need an insulating layer around the material
to reduce the energy transferred from the block to the surroundings
what happens when the power supply is turned on that makes the temperature rise
3 points
1) the current in the circuit does work on the heater
2) transferring energy electrically from the power supply to the heater’s thermal energy store
3) the energy is then transferred to the material’s thermal energy store by heating causing the materials temp to rise
how can you calculate the specific heat capacity of the material
4 points
1) taking the measurements of the current and p.d of the power supply you can calculate its power using P=VI
2) you can then use this to calculate how much energy has been transferred to the heater at the time of each temp reading using E=Pt, where t is the time since the experiment began
3) is you assume all the energy supplied to the heater was transferred to the block you can plot a graph of energy transferred against temperature
4) then find the gradient of the straight part of the graph to work out the specific heat capacity of the block
how can you investigate the specific heat capacity of liquids
by placing the thermometer and heater in an insulated beaker filled with a known mass of the liquid
what can you do to improve this experiment
3 points
1) make the hole in the material a little bigger than the thermometer
2) this means you can put a small amount of water in the hole with the thermometer
3) this helps the thermometer to measure the temperature of the block more accurately as water is a better thermal conductor than air
