IBDP Official Exam Material
FREE Past Paper Questions by Topic
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Topic C: Energy
For both SL and HL students
1a. [2 marks]
1.57 % of the mass of a rock weighing 46.5 kg is uranium(IV) oxide, UO2. 99.28 % of the uranium atoms in the rock are uranium-238, U238.
Show that the mass of the U238 isotope in the rock is 0.639 kg.
1b. [2 marks]
The half-life of 238U is 4.46×109 years. Calculate the mass of 238U that remains after 0.639 kg has decayed for 2.23×1010 years.
1c. [1 mark]
Outline a health risk produced by exposure to radioactive decay.
1d. [1 mark]
Deduce the nuclear equation for the decay of uranium-238 to thorium-234.
1e. [1 mark]
Thorium-234 has a higher binding energy per nucleon than uranium-238. Outline what is meant by the binding energy of a nucleus.
2a. [1 mark]
Gasoline (petrol), biodiesel and ethanol are fuels.
Calculate the energy released, in kJ, from the complete combustion of 5.00 dm3 of ethanol.
2b. [1 mark]
State a class of organic compounds found in gasoline.
2c. [4 marks]
Outline the advantages and disadvantages of using biodiesel instead of gasoline as fuel for a car. Exclude any discussion of cost.
2d. [1 mark]
A mixture of gasoline and ethanol is often used as a fuel. Suggest an advantage of such a mixture over the use of pure gasoline. Exclude any discussion of cost.
2e. [2 marks]
Contrast the molecular structures of biodiesel and the vegetable oil from which it is formed.
2f. [1 mark]
When combusted, all three fuels can release carbon dioxide, a greenhouse gas, as well as particulates. Contrast how carbon dioxide and particulates interact with sunlight.
2g. [2 marks]
Methane is another greenhouse gas. Contrast the reasons why methane and carbon dioxide are considered significant greenhouse gases.
2h. [1 mark]
Suggest a wavenumber absorbed by methane gas.
3a. [3 marks]
Consider the following data for butane and pentane at STP.
Discuss the data.
3b. [2 marks]
In a natural gas power station, 1.00 tonne of natural gas produces 2.41 × 104 MJ of electricity.
Calculate the percentage efficiency of the power station.
1 tonne = 1000 kg
Specific energy of natural gas used = 55.4 MJ kg−1
Specific energy of natural gas used = 55.4 MJ kg−1
4a. [1 mark]
Octane number is a measure of the performance of engine fuel.
Suggest why a high-octane number fuel is preferable.
4b. [2 marks]
Reforming reactions are used to increase the octane number of a hydrocarbon fuel.
Suggest the structural formulas of two possible products of the reforming reaction of heptane, C7H16.
5a. [1 mark]
Red supergiant stars contain carbon-12 formed by the fusion of helium-4 nuclei with beryllium-8 nuclei.
Mass of a helium-4 nucleus = 4.002602 amu
Mass of a beryllium-8 nucleus = 8.005305 amu
Mass of a carbon-12 nucleus = 12.000000 amu
Mass of a beryllium-8 nucleus = 8.005305 amu
Mass of a carbon-12 nucleus = 12.000000 amu
State the nuclear equation for the fusion reaction.
5b. [2 marks]
Explain why fusion is an exothermic process.
5c. [2 marks]
Beryllium-8 is a radioactive isotope with a half-life of 6.70 × 10−17 s.
Calculate the mass of beryllium-8 remaining after 2.01 × 10−16 s from a sample initially containing 4.00 g of beryllium-8.
6a. [1 mark]
Ethanol is a biofuel that can be mixed with gasoline.
Write the equation for the complete combustion of ethanol.
6b. [2 marks]
Outline the evidence that relates global warming to increasing concentrations of greenhouse gases in the atmosphere.
6c. [2 marks]
Explain, including a suitable equation, why biofuels are considered to be carbon neutral.
6d. [1 mark]
State the type of reaction that occurs when ethanol reacts with vegetable oil to form biodiesel.
7a. [1 mark]
Natural gas is an energy source composed mainly of methane.
Calculate the specific energy of methane, in MJ kg−1, using sections 1, 6 and 13 of the data booklet.
7b. [1 mark]
Natural gas is burned to produce steam which turns turbines in an electricity generating power plant.
The efficiency of several sources for power plants is given below.
7e. [1 mark]
List the following products, which are also obtained by fractional distillation, according to decreasing volatility: asphalt, diesel, gasoline, lubricating motor oil.
7f. [3 marks]
Explain how methane absorbs infrared (IR) radiation by referring to its molecular geometry and dipole moment.
7g. [1 mark]
Compare methane’s atmospheric abundance and greenhouse effect to that of carbon dioxide.
8a. [1 mark]
Uranium-235, 235U, is bombarded with a neutron causing a fission reaction.
Two products of the fission of 235U are 144Ba and 89Kr.
Write the nuclear equation for this fission reaction.
8b. [1 mark]
Outline why the reaction releases energy.
8c. [2 marks]
The critical mass for weapons-grade uranium can be as small as 15 kg. Outline what is meant by critical mass.
8d. [1 mark]
The daughter product, 89Kr, has a half-life of 3.15 min.
Calculate the time required, in minutes, for the mass of 89Kr to fall to 6.25 % of its initial value.
9a. [1 mark]
E10 is composed of 10 % ethanol and 90 % normal unleaded fuel.
Ethanol has a Research Octane Number (RON) of 108.6.
Outline how higher octane fuels affect engine performance.
9b. [3 marks]
Show that, for combustion of equal masses of fuel, ethanol (Mr = 46 g mol−1) has a lower carbon footprint than octane (Mr = 114 g mol−1).
9c. [1 mark]
Biodiesel containing ethanol can be made from renewable resources.
Suggest one environmental disadvantage of producing biodiesel from renewable resources.
If you need the markscheme, including the examiners' reports for each question, and more exam and teaching materials on this topic, contact me through the contact page