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1. DF10: Governments and car manufacturers have both investigated ways of reducing
the emissions from car engines. One possible way is the use of `lean burn' technology
for petrol engines.

A lean burn engine uses more air to burn a fixed mass of fuel than does a normal
engine. This…

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(ii) DF10: Exhaust gases from petrol fuelled cars may be less spectacular, but toxic
pollutants such as nitrogen monoxide, NO, are present in the exhaust emitted.


Explain the origin of nitrogen monoxide emitted by p
etrol engines.

....................................................................................................................................

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....................................................................................................................................
[3]
[Total 6 marks]





3. DF10: Heterogeneous catalysts play an…

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3

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(iv) The threeway catalytic converter involves both a reduction and an
oxidation phase. Why is the conversion of NOx
to N2
described as

reduction?

...........................................................................................................................
[1]



(b) (i) Diesel exhaust contains a higher proportion of particulates than petrol
exhaust. Particulates are very small solid soot particles.

Suggest and explain why…

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4. DF5: Heterogeneous catalysts are often used in the reforming process. The process is
called `platforming' when the catalyst is platinum metal. Coke (from side reactions in
the process) reduces the efficiency of the catalyst.

Describe the stages involved in heterogeneous catalysis and explain why the formation
of coke can…

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DF5

5.
The diagram illustrates a model for heterogeneous catalysis.






The following phrases describe some of the steps labelled on the above diagram.

Write the numbers of the step or steps corresponding to each phrase.

Bonds in reactants weaken and break
Step(s) .................................................

New bonds in products form
Step(s) .................................................…

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DF5

6. Catalysts also play a role in the oil industry in the production of more useful
hydrocarbons from longer chain fractions.

Zeolite catalysts replaced the traditional silica/alumina catalysts in the 1960s.

The following box illustrates some of the reactions catalysed by zeolites.






(i)
Use words from the following list…

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name ........................................................................................................................
[4]



(iv) Suggest one
reason why the hydrocarbon formed in reaction B is more useful
than the hydrocarbon it is made from.

....................................................................................................................................

....................................................................................................................................
[1]
[Total 10 marks]



DF8

7. The longer a car engine runs, the more exhaust gases are produced. Use the steps
below to obtain…

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­1
answer .......................... mol s
[2]






9

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(iii) Calculate the volume of exhaust gases produced per second.


One mole of molecules of the exhaust gases occupies 60 dm3
at the high
temperature in the exhaust.



3 ­1
answer ........................ dm s
[1]
[Total 5 marks]

DF5



8. Catalytic converters can reduce still further the pollution from lean…

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