(i) Explain why fusion, combining two smaller nuclei into a larger nucleus, releases vast amounts of energy. Use section 36 of the data booklet.

(ii) Outline one advantage of fusion as a source of energy.

Radioactive phosphorus, ³³P, has a half-life of 25.3 days.

(i) Calculate ³³P decay constant λ and state its unit. Use section 1 of the data booklet.

(ii) Determine the fraction of the ³³P sample remaining after 101.2 days.

(i) Calculate the specific energy of the lithium ion battery, in MJ kg⁻¹, when 80.0 kg of fuel in the battery releases 1.58 × 10⁷ J. Use section 1 of the data booklet.

(ii) The specific energy of gasoline is 46.0 MJ kg⁻¹. Suggest why gasoline may be considered a better energy source than the lithium ion battery based on your answer to part (a) (i).

(i) The energy density of gasoline is 34.3 MJ dm⁻³. Calculate the volume of gasoline, in dm³, that is equivalent to the energy in 80.0 kg of fuel in the lithium ion battery. Use section 1 of the data booklet.

(ii) The efficiency of energy transfer by this lithium ion battery is four times greater than that of gasoline. Determine the distance, in km, the car can travel on the lithium ion battery power alone if the gasoline-powered car uses 1.00 dm³ gasoline to travel 32.0 km.

Show that the mass of the ${}_{238}\mathrm{U}$ isotope in the rock is $0.639 \mathrm{kg}$.

The half-life of ²³⁸U is $4.46\times {10}^9$ years. Calculate the mass of ²³⁸U that remains after $0.639 \mathrm{kg}$ has decayed for $2.23\times {10}^{10}$ years.

Outline a health risk produced by exposure to radioactive decay.

Deduce the nuclear equation for the decay of uranium-238 to thorium-234.

Thorium-234 has a higher binding energy per nucleon than uranium-238. Outline what is meant by the binding energy of a nucleus.

Outline how the spectra of light from stars can be used to detect the presence of carbon.

Deduce the identity of X.

Outline why this reaction results in a release of energy.

Nuclear fusion reactors are predicted to become an important source of electrical energy in the future. State two advantages of nuclear fusion over nuclear fission.

State the equation for the complete transesterification of the triglyceride given below with methanol.

Outline why the fuel produced by the reaction in (a) is more suitable for use in diesel engines than vegetable oils.

Suggest why it is only in recent years that specific predictions of the future effects of fossil fuel combustion have been made.

Carbon dioxide has two different bond stretching modes illustrated below.

Predict, with an explanation, whether these stretching modes will absorb infrared radiation.

Outline, giving the appropriate equation(s), how increasing levels of carbon dioxide will affect the pH of the oceans.

Many combustion processes also release particulate matter into the atmosphere. Suggest, giving your reason, how this might affect the temperature of the Earth’s surface.

Calculate the energy released, in $\mathrm{kJ}$, from the complete combustion of $5.00 {\mathrm{dm}}^3$ of ethanol.

State a class of organic compounds found in gasoline.

Outline the advantages and disadvantages of using biodiesel instead of gasoline as fuel for a car. Exclude any discussion of cost.

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.

Contrast the molecular structures of biodiesel and the vegetable oil from which it is formed.

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.

Methane is another greenhouse gas. Contrast the reasons why methane and carbon dioxide are considered significant greenhouse gases.

Suggest a wavenumber absorbed by methane gas.

Discuss how the octane number changes with the molecular structure of the alkanes.

Catalytic reforming and cracking reactions are used to produce more efficient fuels. Deduce the equation for the conversion of heptane to methylbenzene.

State how these gases are produced, giving the appropriate equation(s).

Outline how the carbon monoxide is then converted to a hydrocarbon fuel.

One fusion reaction occurring in the sun is the fusion of deuterium, ${}_1^{2}H$, with tritium, ${}_1^{3}H$, to form helium, ${}_2^{4}He$. State a nuclear equation for this reaction.

Explain why this fusion reaction releases energy by using section 36 of the data booklet.

State the technique used to show that the sun is mainly composed of hydrogen and helium.

Coloured molecules absorb sunlight. Identify the bonding characteristics of such molecules.

Calculate the specific energy of octane, C₈H₁₈, in kJ kg^–1 using sections 1, 6 and 13 of the data booklet.

A typical wood has a specific energy of 17 × 10³ kJ kg^–1. Comment on the usefulness of octane and wood for powering a moving vehicle, using your answer to (a).

If you did not work out an answer for (a), use 45 × 10³ kJ kg^–1 but this is not the correct answer.

State the name of one renewable source of energy other than wood.

State two reagents required to convert vegetable oil to biodiesel.

Deduce the formula of the biodiesel formed when the vegetable oil shown is reacted with the reagents in (a).

Explain, in terms of the molecular structure, the critical difference in properties that makes biodiesel a more suitable liquid fuel than vegetable oil.

Determine the specific energy, in kJ$$g⁻¹, and energy density, in kJ$$cm⁻³, of a particular biodiesel using the following data and section 1 of the data booklet.

Density = 0.850 g$$cm⁻³; Molar mass = 299 g$$mol⁻¹;

Enthalpy of combustion = 12.0 MJ$$mol⁻¹.

“Knocking” in an automobile (car) engine can be prevented by increasing the octane number of the fuel. Explain, including an equation with structural formulas, how heptane, C₇H₁₆, could be chemically converted to increase its octane number.

Many like to refer to our “carbon footprint”. Outline one difficulty in quantifying such a concept.

Climate change or global warming is a consequence of increased levels of carbon dioxide in the atmosphere. Explain how the greenhouse effect warms the surface of the earth.

Outline how water and carbon dioxide absorb infrared radiation.

State one advantage and one disadvantage for each energy source in the table.

Calculate the specific energy of hydrogen, stating its units. Refer to sections 1, 6 and 13 of the data booklet.

Hydrogen has a higher specific energy than petrol (gasoline) but is not used as a primary fuel source in cars. Discuss the disadvantages of using hydrogen.

Identify which region, A or B, corresponds to each type of radiation by completing the table.

Oceans can act as a carbon sink, removing some CO₂(g) from the atmosphere.

CO₂(g) $\rightleftharpoons$ CO₂(aq)

Aqueous carbon dioxide, CO₂(aq), quickly reacts with ocean water in a new equilibrium reaction. Construct the equilibrium equation for this reaction including state symbols.

Describe how large amounts of CO₂ could reduce the pH of the ocean using an equation to support your answer.

Suggest an equation for the production of syngas from coal.

The Fischer-Tropsch process, an indirect coal liquefaction method, converts CO(g) and H₂(g) to larger molecular weight hydrocarbons and steam.

Deduce the equation for the production of octane by this process.

Suggest a reason why syngas may be considered a viable alternative to crude oil.

Outline the major technical problem affecting the direct use of vegetable oils as fuels in internal combustion engines and the chemical conversion that has overcome this.

State the formula of a fuel that might be produced from the vegetable oil whose formula is shown.

Outline why biofuels are considered more environmentally friendly, even though they produce more carbon dioxide per kJ of energy than petroleum based fuels.

Identify one naturally occurring greenhouse gas, other than carbon dioxide or water vapour, and its natural source.

Formulate an equation that shows how aqueous carbon dioxide produces hydrogen ions, H⁺(aq).

The concentrations of oxygen and nitrogen in the atmosphere are much greater than those of greenhouse gases. Outline why these gases do not absorb infrared radiation.

Explain the molecular mechanism by which carbon dioxide acts as a greenhouse gas.

Discuss the significance of two greenhouse gases, other than carbon dioxide, in causing global warming or climate change.

Compare and contrast the process of nuclear fusion with nuclear fission.

Dubnium-261 has a half-life of 27 seconds and rutherfordium-261 has a half-life of 81 seconds.

Estimate what fraction of the dubnium-261 isotope remains in the same amount of time that $\frac{3}{4}$ of rutherfordium-261 decays.

Natural uranium needs to be enriched to increase the proportion of ²³⁵U. Suggest a technique that would determine the relative abundances of ²³⁵U and ²³⁸U.

Explain how ²³⁵U fission results in a chain reaction, including the concept of critical mass.

Suggest one reason why there is opposition to the increased use of nuclear fission reactors.

Compare and contrast fission and fusion in terms of binding energy and the types of nuclei involved.

Suggest two advantages that fusion has over fission.

The amount of ²²⁸Ac in a sample decreases to one eighth $\left(\frac{1}{8}\right)$ of its original value in about 18 hours due to β-decay. Estimate the half-life of ²²⁸Ac.

Identify an element, other than carbon and hydrogen, found at significant concentrations in fossil fuels.

Petroleum contains many hydrocarbons. Explain how these are separated by fractional distillation.

Determine the specific energy and energy density of petrol (gasoline), using data from sections 1 and 13 of the data booklet. Assume petrol is pure octane, C₈H₁₈. Octane: molar mass = 114.26 g mol⁻¹, density = 0.703 g cm⁻³.

Outline why the energy available from an engine will be less than these theoretical values.

Outline two reasons why oil is one of the world’s significant energy sources.

Formulate an equation for the cracking of C₁₆H₃₄ into two products with eight carbon atoms each.

Identify, giving a reason, which product in (b)(i) could be used in petrol (gasoline).

Outline how higher octane fuels help eliminate “knocking” in engines.

The performance of hydrocarbons as fuels can be improved by catalytic reforming.

Outline how catalytic reforming increases a fuel’s octane rating.

Suggest another advantage and one disadvantage of solar energy.

Light can be absorbed by chlorophyll and other pigments.

Consider molecules A and B represented below.

Identify, with a reason, the molecule that absorbs visible light.

State a physical property of vegetable oils that makes them very difficult to use as fuel in internal combustion engines.

Describe how vegetable oils can be converted to a more suitable fuel.

Contrast the importance of carbon dioxide and methane as greenhouse gases.

Explain, using an equation, the effect of increased carbon dioxide in the atmosphere on the pH of lake water.

Explain fusion reactions with reference to binding energy.

Outline why the term breeder is used for the reactors.

Deduce the fission reaction when ²³⁹Pu is bombarded with a neutron to produce ¹³³Xe and ¹⁰³Zr.

Nuclear disasters release radioactive caesium into the atmosphere, which presents serious health risks.

Cs-137 has a half-life of 30 years.

Calculate the percentage of Cs-137 remaining in the atmosphere after 240 years.

Formulate equation(s) for the conversion of coal and steam to methane.

Calculate the specific energy, in kJ g⁻¹, of methane.

Comment on the specific energies of hydrogen and methane.

Calculate the mass, in kg, of carbon dioxide produced by the complete combustion of 72.0 dm³ octane, C₈H₁₈.

Density of C₈H₁₈ = 703 g dm⁻³

C₈H₁₈ (l) + 12.5O₂ (g) → 8CO₂ (g) + 9H₂O (g)

Explain the effect of the increasing concentration of atmospheric carbon dioxide on the acidity of oceans.

(i) Describe the changes that occur at the molecular level when atmospheric carbon dioxide gas absorbs infrared radiation emitted from the Earth’s surface.

(ii) Other than changes to the acidity of oceans, suggest why the production of carbon dioxide is of greater concern than the production of water vapour.

State the structural feature of chlorophyll that enables it to absorb visible light.

Vegetable oils are too viscous for use as liquid fuels. Describe, using an equation, how a vegetable oil, such as that shown, is converted to oils with lower viscosity by reaction with methanol, CH₃OH.

Suggest why a high-octane number fuel is preferable.

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.

The ¹H NMR spectrum of one of the products has four signals. The integration trace shows a ratio of the areas under the signals of 9 : 3 : 2 : 2.

Deduce the structural formula of the product.

Calculate the thermal efficiency of a steam turbine supplied with steam at 540°C and using a river as the choice of sink at 23 °C.

Power plants generating electricity by burning coal to boil water operate at approximately 35% efficiency.

State what this means and suggest why it is lower than the thermal efficiency.

Write the nuclear equation for this fission reaction.

Outline why the reaction releases energy.

The critical mass for weapons-grade uranium can be as small as 15 kg. Outline what is meant by critical mass by referring to the equation in (a)(i).

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.

Calculate the specific energy of methane, in MJ kg⁻¹, using sections 1, 6 and 13 of the data booklet.

Calculate the maximum electric energy output, in MJ, which can be obtained from burning 1.00 kg of methane by using your answer from (a).

Hydroelectric power plants produced 16 % of the world’s energy in 2015, down from 21 % in 1971.

Suggest why hydroelectric power production has a higher efficiency than the other sources given in (b) and why its relative use has decreased despite the high efficiency.

Reason for higher efficiency:

Reason for decreased use:

Methane can also be obtained by fractional distillation of crude oil.

Draw a circle on the diagram to show where the methane fraction is withdrawn.

List the following products, which are also obtained by fractional distillation, according to decreasing volatility: asphalt, diesel, gasoline, lubricating motor oil.

Explain how methane absorbs infrared (IR) radiation by referring to its molecular geometry and dipole moment.

Compare methane’s atmospheric abundance and greenhouse effect to that of carbon dioxide.

Determine the other product of the fission reaction of plutonium-239.

Outline the concept of critical mass with respect to fission reactions.

Outline one advantage of allowing all countries access to the technology to generate electricity by nuclear fission.

State one advantage of using fusion reactions rather than fission to generate electrical power.

⁹⁰Sr, a common product of fission, has a half-life of 28.8 years.

Determine the number of years for the activity of a sample of ⁹⁰Sr to fall to one eighth ($\frac{1}{8}$) of its initial value.

Crude oil can be converted into fuels by fractional distillation and cracking.

Contrast these two processes.

Determine the specific energy, in kJ g⁻¹, and energy density, in kJ cm⁻³, of hexane, C₆H₁₄. Give both answers to three significant figures.

Hexane: M_r = 86.2; ΔH_c = −4163 kJ mol⁻¹; density = 0.660 g cm⁻³

Specific energy: 

Energy density:

Hydrocarbons need treatment to increase their octane number to prevent pre-ignition (knocking) before they can be used in internal combustion engines.

Describe how this is carried out and the molecular changes that take place.

State one greenhouse gas, other than carbon dioxide.

Describe the effect of infrared (IR) radiation on carbon dioxide molecules.

Outline one approach to controlling industrial emissions of carbon dioxide.

The regular rise and fall of sea levels, known as tides, can be used to generate energy.

State one advantage, other than limiting greenhouse gas emissions, and one disadvantage of tidal power.

Advantage:

Disadvantage:

Write the equation for the complete combustion of ethanol.

Outline the evidence that relates global warming to increasing concentrations of greenhouse gases in the atmosphere.

Explain, including a suitable equation, why biofuels are considered to be carbon neutral.

State the type of reaction that occurs when ethanol reacts with vegetable oil to form biodiesel.

State the nuclear equation for the fusion reaction.

Explain why fusion is an exothermic process.

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.

Deduce the equation for the transesterification reaction of pentyl octanoate, C₇H₁₅COOC₅H₁₁, with methanol.

Outline why the ester product of this reaction is a better diesel fuel than pentyl octanoate.

Ethanol has a Research Octane Number (RON) of 108.6.

Outline how higher octane fuels affect engine performance.

Show that, for combustion of equal masses of fuel, ethanol (M_r = 46 g mol⁻¹) has a lower carbon footprint than octane (M_r = 114 g mol⁻¹).

Biodiesel containing ethanol can be made from renewable resources.

Suggest one environmental disadvantage of producing biodiesel from renewable resources.

Discuss the data.

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

The structure of chlorophyll is given in section 35 of the data booklet.

State the feature of the chlorophyll molecule that enables it to absorb light in the visible spectrum.

Evaluate the use of biodiesel in place of diesel from crude oil.

Strength:

Limitation: