International Baccalaureate Physics
4/PSOW
Energy Density of Fuels
IB Criteria Assessed
All fuels that can be burned have a particular energy density, or how much energy is
packed in per kilogram of fuel. Usually, for something like cars, we want fuels that
have a high energy density, so we don’t have to lug so much around with us. One
benefit of gasoline over coal is that it has a higher energy density. In this lab, you
will compare the energy density of fuels that can be used easily in the laboratory.
Data Collection and Processing,
Conclusion and Evaluation
Criteria
assessed
2
3
Level
awarded
D
Aim:
1.
2.
Aspect
1
To compare the relative energy density of fuels.
To compare our measured energy densities with the actual literature values.
DCP
CE
Theory:
ISM score
The equation for energy density is….
Energy density = energy of fuel / mass of fuel
A rough assumption will be that the energy from burning the
fuel can be put directly into heating water.
Diagram:
Temperature Probe
If so, energy to heat water is = mc∆T, where
Water
m = mass water
c = specific heat capacity of water
∆T = rise in temp. of water
Liquid Spirit Burner
The mass of fuel used can be measured by the difference in
mass of a spirit burner as it burns.
Laptop
Electronic
Balance
Method:
1.
2.
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7.
8.
9.
Set up the apparatus as shown in the diagram.
Use a reasonable amount of water given the size of your flame. 100 mL is a good starting point. Record this.
Record the initial temp of your water.
Lower the water (which should be on wire gauze) just over the flame.
Zero the scale so that it shows negative values as flame burns.
Set the laptop and temperature probe so that they measure water temperatures. Stir constantly.
Record appropriate data so as to obtain the energy density of water.
Record the uncertainties in the collected data.
Repeat this method using other fuels. Keep in mind that other fuels may heat the water much slower or faster, and you
may want to use different amounts of water to allow for this.
Data Processing and Presentation:
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Collect appropriate data and present this in a way which will allow for easy interpretation.
Include the uncertainties of measurement in your recorded data.
Plot a suitable graph from which you can analyze the energy density of the fuels.
Include the uncertainty in your calculated answer.
Conclusion and Evaluation:
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Make valid conclusions related to fuel densities found. Compare the fuel densities relative to each other, and to literature
values.
Evaluate the method, including any modifications you had to make to overcome problems
Include an evaluation of the apparatus used.
Suggest ways in which the procedure (and apparatus) could be modified in order to improve future investigations.
The above information was given to the student by the instructor. What follows is the student’s own work.
© Dickinson / Dingrando - ISM
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