HKCEE Chemistry Past Paper fossil fuels

Topics: Petroleum, Oxygen, Coal Pages: 8 (1827 words) Published: November 19, 2013
CE : Section 5 Fossil Fuels

1.93 1(c)
Alkenes can be obtained from petroleum fractions by a process called 'cracking’. Using a suitable petroleum fraction, a student carried out this process in the laboratory and collected the gaseous product over water.

(i)What is 'cracking’ ?
(ii)Draw a labelled diagram of a laboratory set-up that can be used for carrying out the process and collecting the gaseous product.
(iii)An important safety precaution in the experiment is to prevent sucking back.
(1)What is the potential hazard if sucking back occurs ?
(2)How can sucking back be prevented ?
(iv)If the gaseous product decolorizes a solution of bromine in tetrachloromethane, can you conclude that the gaseous product in ethene ? Explain your answer.
(8 marks)

2.93 3(b)(iii)
When chemical wastes such as methylbenzene and tetrachloromethane are burnt in the incinerator in the plant, several pollutants including sulphur dioxide are produced.
(1)Explain why sulphur dioxide is emitted from the incinerator.
(2)Name TWO pollutants other than sulphur dioxide which are emitted from the incinerator and state ONE harmful effect for each pollutant. (5 marks)

3.94 6(a)
The following experimental set-up was used to determine the empirical formula of an oxide of copper.

In the experiment, 8.58 g of an oxide of copper, after complete reaction, produced 7.62 g of copper.
(i)*Deduce the empirical formula of the oxide of copper.
(ii)Write an equation for the reaction that occurred in the combustion tube.
(iii)State TWO potential hazards associated with this experiment, and suggest a safety precaution for each hazard.
(iv)At the end of the reaction, heating was stopped. However, it was necessary to continue passing the town gas through the combustion tube until the tube had cooled down. Explain why.
(Relative atomic masses : Cu = 63.5, O = 16.0)
(8 marks)

4.95 8(a)
The fumes emitted from a factory using diesel fuel contain several gaseous pollutants. One of these pollutants, Z, has a choking smell and can decolourize bromine water.
(i)(1)What is Z ?
(2)What is the effect of Z on the environment ?
(3)Suggest ONE way to reduce the amount of Z in the fumes.
(ii)(1)Suggest ONE other pollutant that is present in the fumes.
(2)Explain how this pollutant is formed.
(3)What is the effect of this pollutant on the environment ?
(4)Suggest ONE way to reduce the amount of this pollutant in the fumes.
(iii)If a fire is caused by the burning of diesel fuel, what type of fire extinguisher should not be used to put out the fire ? (8 marks)

5.96 1
A student suggested the following immediate actions to deal to three domestic accidents. However, these actions are considered inappropriate.

Suggested action
(1)Some drain cleaner, which contains mainly concentrated sodium hydroxide solution, is split onto the hand. Use vinegar to neutralize the sodium hydroxide solution left on the hand. (2)During cooking, some oil in a cooking pan catches fire.

Use water to put out the fire.
(3)Leakage of town gas occurs in a kitchen.
Turn on an exhaust fan in the kitchen to remove the town gas.

In each case, explain why the action is inappropriate and suggest a proper action. (8 marks)

6.96 3
'Fossil fuels' such as petroleum and coal constitute the world's major source of energy. However, many countries have been developing alternative energy sources.
(a)Why are petroleum and coal called 'fossil fuels'?
(b)give TWO reasons why it is necessary to develop alternative energy sources.
(c)Nuclear power is used as an alternative to fossil fuels in many countries. Suggest ONE advantage and ONE disadvantage of using nuclear power.
(d)Suggest ONE energy sources, other than nuclear power, that can be used as an alternative to fossil fuels. (6 marks)

7.96 9(a)
The diagram below shows a longitudinal section of a fire...
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