Latent heat + Insulation practical Flashcards
Draw and label a diagram showing the experiment in measuring the specific latent heat of vaporisation of water
file:///C:/Users/44748/Documents/measuring%20specific%20heat%20capacity,%20latent%20heat%20and%20density.pdf
Describe the experiment measuring the specific latent heat of vaporisation of water
1) Switch on the kettle and allow the water to boil
2) As soon as the water starts to boil, record the mass and start the stopwatch
3) Allow the kettle to boil for about ten minutes and record the mass
Calculate the specific latent heat of vaporisation of water
using the experiment
Power of the kettle = 40 watts
Time = 10 minutes
Initial mass = 200g
Final mass = 90g
E = m x Lv (subscript v)
Energy = Power x Time
Energy = 40 x (10 x 60) - to get the time into seconds
Energy = 24000 J
Mass = intial mass - final mass
Mass = 0.2 - 0.09 = 0.11 kg
E = m x Lv
24000 = 0.01 x Lv
Lv = 24000/0.01
Lv = 2,400,000
The power of the kettle is 40 watts
What does this statement mean
40 joules of electrical energy is being used per second
What are the problems with this experiment
Explain why the value for the specific latent heat of vaporisation of water is lower than it should be
A large amount of energy will be lost from the kettle and water to the surroundings, therefore the value for energy should be lower than the actual value hence the value for the specific latent heat of vaporisation of water should be lower.
Describe the experiment for investigating insulation
1) Using the plastic jug, pour 150 ml of hot water into the insulated beaker
2) Cover the beaker with insulation and insert the thermometer
3) Record the temperature and continue to record the temperature for every minute for 10 minutes
4) Repeat this experiment, but cover the beaker with a different insulating material. The same mass of water should be used each time.
Draw and label a diagram showing the experiment of investigating insulation
file:///C:/Users/44748/Documents/required%20practical%20investigating%20insulation.pdf
Draw a graph
Time (in mins) Temperature (in °C)
0 77
1 77
2 76
3 75
4 74
5 73
6 72.5
7 72
8 71
9 71
10 70
file:///C:/Users/44748/Documents/required%20practical%20investigating%20insulation.pdf
Draw to a conclusion using these results
file:///C:/Users/44748/Documents/required%20practical%20investigating%20insulation.pdf
Conclusion
Foam was the best insulator because it produced the smallest change in temperature
4 layers of foam provided the best level of insulation, because after this there was little variation in temperature change
State the dependent variable of the insulation experiment
Temperature is the dependent variable
The dependent variable is the variable that is measured for each change in the independent variable
State the independent variable of the insulation experiment
The type/layers of insulating material is the independent variable
Independent variable - the variable that is changed
State the control variable of the insulation experiment
The volume of the water, the mass of the insulating material and the starting temperature of the water for each experiment are the control variable
Control variable are variables that we do not allow to change
What does the energy transfer per second through a layer of insulating material depend on
What would be needed, to have the greatest amount of energy transfer through an insulating material
The energy transfer per second through a layer of insulating material depends on:
the temperature difference across the material
the thickness of the material
the thermal conductivity of the material
The greater the temperature difference across the material, the less thicker and the lower thermal conductivity of the material, the greater energy transfer through a layer of insulating material
