1. Many organisms use the aerobic respiration of glucose, C6H12O6, to release useful energy.
(a) The overall equation for aerobic respiration is the same as for the complete combustion of
C6H12O6.
(i) Write the equation for the aerobic respiration of C6H12O6.
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(ii) Explain, in terms of bond breaking and bond forming, why this reaction is exothermic.

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(b) The table shows some enthalpy changes of combustion, ΔHc.

(i) What is meant by the term enthalpy change of combustion, ΔH_c?

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(ii) The enthalpy change of formation, ΔH_f, of glucose, C₆H₁₂O₆, cannot be determined
directly. The equation for this enthalpy change is shown below.
6C(s) + 6H₂(g) + 3O₂(g) ->C₆H₁₂O₆(s)
Suggest why the enthalpy change of formation of C6H12O6 cannot be determined
directly.
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(iii) Use the ΔH_c values in the table to calculate the enthalpy change of formation of
C₆H₁₂O₆.

                                                     ΔH_f = ……………………………………. kJ mol^–1 [3]
[Total: 9]

2. The alcohols are an example of an homologous series.
The table shows the boiling points for the first four members of straight-chain alcohols.

(a) (i) What is the general formula of a member of the alcohol homologous series?
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(ii) Deduce the molecular formula of the alcohol that has 13 carbon atoms per molecule.
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(b) Alcohols contain the hydroxyl functional group.
What is meant by the term functional group?
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(c) (i) At room temperature and pressure, the first four members of the alcohol homologous
series are liquids whereas the first four members of the alkanes homologous series are
gases.
Explain this difference.
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(ii) Methylpropan-1-ol and butan-1-ol are structural isomers. Methylpropan-1-ol has a lower
boiling point than butan-1-ol.
Suggest why.
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(d) Alcohols, such as methanol, can be used as fuels.
(i) Write equations for the complete and incomplete combustion of methanol.
complete: …………………………………………………………………………………………….
incomplete: …………………………………………………………………………………………. [2]
(ii) Suggest what conditions might lead to incomplete combustion of methanol.
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(iii) In addition to its use as a fuel, methanol can be used as a solvent and as a petrol additive
to improve combustion.
State another large-scale use of methanol.
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(e) Butan-1-ol can be oxidised by heating under reflux with excess acidified potassium
dichromate(VI).
Write an equation for the reaction that takes place.
Use [O] to represent the oxidising agent.
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(f) Butan-1-ol is one of the structural isomers of C₄H₁₀O.
(i) Write the name and draw the structure of the structural isomer of C4H10O that is a tertiary
alcohol.
name: ……………………………………………………
structure:                                                                                                                          [2]

(ii) Draw the structure of the structural isomer of C₄H₁₀O that can be oxidised to form
butanone.                                                                                                                          [1]

[Total: 18]

3. Nitrogen monoxide is an atmospheric pollutant, formed inside car engines by the reaction between
nitrogen and oxygen.
N₂(g) + O₂(g) ->2NO(g)               ΔH = +66 kJ mol^–1
This reaction is endothermic.
(a) (i) Explain the meaning of the term endothermic.
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(ii) What is the value for the enthalpy change of formation of nitrogen monoxide?
answer = ……………………………………. kJ mol^–1 [1]
(b) (i) Complete the enthalpy profile diagram for the reaction between nitrogen and oxygen.
On your diagram
• add the product
• label the activation energy as E_a
• label the enthalpy change as ΔH.

[3]
(ii) Explain the meaning of the term activation energy.
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(c) A research chemist investigates the reaction between nitrogen and oxygen.
She mixes nitrogen and oxygen gases in a sealed container.
She then heats the container at a constant temperature for one day until the gases reach a
dynamic equilibrium.
(i) Explain, in terms of the rate of the forward reaction and the rate of the backward reaction,
how the mixture of N₂(g) and O₂(g) reaches a dynamic equilibrium containing N₂(g),
O₂(g) and NO(g).
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(ii) The research chemist repeats the experiment at the same temperature using the same
initial amounts of N₂(g) and O₂(g). This time she carries out the experiment at a much
higher pressure.
Suggest why
• much less time is needed to reach dynamic equilibrium
• the composition of the equilibrium mixture is the same as in the first experiment.
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(iii) The reaction between nitrogen and oxygen in a car engine does not reach a dynamic
equilibrium.
Suggest why not.
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(d) Nitrogen monoxide is a radical.
What does this tell you about a molecule of nitrogen monoxide?
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(e) Oxides of nitrogen, NOx, are atmospheric pollutants.
(i) Nitrogen monoxide reacts with oxygen to form NO₂.
Write an equation for the formation of NO₂ from nitrogen monoxide and oxygen.
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(ii) Aeroplane engines produce nitrogen monoxide.
Describe, with the aid of equations, how nitrogen monoxide catalyses ozone depletion in
the stratosphere.
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(iii) Outline the use of infrared spectroscopy in identifying air pollutants such as NO_x.
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[Total: 21]