cameroon gce june 2007 chemistry Paper 2
To DOWNLOAD CAMEROON GCE JUNE 2007 CHEMISTRY Paper 2 click on the link below
JUNE 2007
SECTION A
l. The four metals below are written in order of decreasing reactivity Magnesium, aluminium, iron, copper
(a) Suggest a reason why the reaction between magnesium, and aluminum oxide can not take place (l mark)
(b) write an Equation for the reaction between magnesium and copper (II) oxide (l mark)
(c) Suggest with a reason which of these metals
would be most suitable for making:
(i) Car bodies.
Reason…………………..
(ii) fireworks….
reason…..
(iii) window frames,
reason. (6marks)
(d) Copper is widely used for the construction of hot
(e)To produce aluminium economically,large quantities of electricity are needed. Bearing this in prints, suggest a reason for siting plants for extraction
of aluminium in mountains regions (l mark)
2. When molten sodium chloride is electrolysed using inert electrodes, a gas is produced as one of the products.
(a) The electrodes could be made of which substance?
.(l mark)
(b)Which gas is produced (l mark)
(c)Write ionic equations for the reaction occurring at
(i) The anode…
(ii)The cathode.. v (2marks)
(b) If a current of 4A is passed through sodium chloride for 20 minutes, calculate:
(i) the number of Faradays used in this experiment
(ii) the number of moles of sodium atoms produced
(iii) the volume of gas produced at room temperature
and atmospheric pressure (r.tp.) (6marks)
3. For the organic compounds given below :
A. Ethane B. Ethene C. Ethanol D. Ethylethanoate
(a)(i)Give the structural formula of each of the compounds
(ii) Give the homologous series to which each compound belongs.
COMPOUND
|
HOMOLOGOUS SERIES
|
A
|
|
B
|
|
C
|
|
D
|
|
(4 marks )
(a) Name the reagent and state the reaction conditions necessary for converting
(i) ethanol to ethene: reagents reaction conditions ;
(ii) ethene to ethane: reagents reaction conditions (2marks)
(b) Describe a chemical test to distinguish between ethane and ethene (2marks)
(c) (i)Which organic compound could be used to
prepare ethylethanoate from ethanol
(ii) Give one physical property by which ethyl ethanoate could be recognised
4. A stream of dry ammonia was passed over black copper(II) oxide in a strongly heated combustion tube. The gas issuing from the tube was first passed through a U-tube immersed in a beaker of cold water, and then collected over water. A colourless neutral gas was collected and the water over which it was collected became alkaline, Moisture condensed in the U-tube.
(a) What physical change will you observe of the copper(II) oxide at the end of the experiment’?
(1 mark)
(b) Which gas was collected
Give ONE test you could carry out to confirm your answer(3 marks)
(c) Why was the water over which the gas was collected
alkaline? (1 mark)
(d) Where did the moisture come from? (l mark)
(e) What property of ammonia is being
demonstrated (l mark)
(f) Write an equation for the reaction between
ammonia and copper(II) oxide (2 marks)
(Give ONE industrial use of ammonia (1 mark)
5. When lumps of zinc are added to dilute sulphuric acid,a reaction represented by the equation below takes place
Zn + H2SO4 —–>ZnSO4(aq) + H2(e) A H = -420 kj/mol
(a) Give TWO observations that could be made during
this reaction. (2 marks)
(b) State TWO ways in which this reaction could be
made to go faster (2 marks)
(c)Draw a labelled energy level diagram l or this reaction
(d)If 3.25g of zinc were added to excess dilute sulphuric acid,
(i) What volume of hydrogen at room temperature and atmospheric pressure (r.tp.) would be collected?
(ii) What mass of zinc sulphate crystals would be
obtained? (4 marks)
6. The inside of a copper kettle becomes covered with scale (calcium carbonate) when used in a “hard water” area.
(a) What is “hard water”? (2 marks)
(b) Mention the two types of hardness in water
(2 marks)
(c) Dilute hydrochloric acid is added to remove the scale.
(i) What TWO things would you notice happening when the acid is poured onto the scale?
(ii) Give TWO products formed when hydrochloric acid reacts with this scale.
(iii) Explain why dilute hydrochloric acid should not
be used to remove scale from aluminium Keltic ( 6 marks)
SECTION B
Answer any TWO questions in this section. All questions cany equal marks. Where arfropriate, and diagrams should be given to clarify your answers. Write your answers in the lined s which follow this section.
Useful data will be found on the last page
7. Ammonia and sulphur dioxide are often used for the manufacture of important industrial chemicals. Outline the manufac ture of one important mineral acid from each of these gases. State TWO important large scale uses of the acids …(25marks)
8.a) Describe an experiment to show how you would determine the heat of neu tralisation of hydrochloric acid and sodium hydroxide solution. In your description indicate what precautions must be taken and the data collected.
(b) In one such experiment 100cm3 of M HCL } were mixed with an equal volume of M NaOH(aq). Both solutions were initially at 25°C The temperature of the mixture was found to rise to a maximum of 31.8°C Use this information to calculate the heat of neutralisation of hydrochloric acid ……….. (25marks)
9.Some methods of preparing salts are:
(a) Action of acid on metals.
(b) Action of acids on insoluble bases
(c)Double decomposition
