NATIONAL SPORT SCHOOL
Mark
HALF-YEARLY EXAMINATION 2016
Track 3
FORM 4
Question
Max. Mark
CHEMISTRY
TIME: 1 hr 30 mins
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Global
Mark
Mark
85% of Theory Paper
15% Practical
100% Final Score
DO NOT WRITE ABOVE THIS LINE
Name: __________________________________
Class: ___________
Useful data: A copy of the Periodic Table is printed below.
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Page 1 of 13
SECTION A:
Answer ALL questions in this section, using the spaces provided. This section
carries 60 marks.
1a. In each equation below, state which substance is oxidised and which
substance is reduced:
i.
C6H12O6 (s)
+ 6O2 (g)
6CO2
(g)
+ 6H20(l)
substance which is oxidised: ____________________________________
substance which is reduced: ____________________________________
(2 marks)
ii. Zn(s) + CuSO4 (aq)
ZnSO4
(aq)
+ Cu
(s)
substance which is oxidised: ____________________________________
substance which is reduced: ____________________________________
(2 marks)
iii. Cl2(g) + H2S(aq)
2HCl(aq) + S(s)
substance which is oxidised: _____________________________________
substance which is reduced: _____________________________________
(2 marks)
b. Identify the oxidizing and the reducing agents in the following
reactions:
i.
Fe2O3 + 3CO
2Fe + 3CO2
the oxidizing agent is __________________________________________
the reducing agent is __________________________________________
(2 marks)
ii. H2S + Br2
2HBr + S
the oxidizing agent is __________________________________________
the reducing agent is ___________________________________________
(2 marks)
(Total: 10 marks)
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2a. This question is about the stability of sodium and copper compounds
when heated.
i.
What is the effect of heating sodium carbonate?
___________________________________________________________
(2 marks)
ii. What is the effect of heating copper carbonate?
___________________________________________________________
(2 marks)
iii. What is the effect of heating sodium nitrate?
___________________________________________________________
(2 marks)
iv. What is the effect of heating copper(II) nitrate?
____________________________________________________________
(2 marks)
2b. A copper rod and an iron rod stand in an electrolyte. If you connect a
bulb between them, it will light dimly. Suggest two metals you could use
to get a brighter light.
___________________________________________________________
(2 marks)
(Total: 10 marks)
3a. Write the 2 half equations for each of the reactions below:
i.
2Li + S
Li2S
___________________________________________________________
___________________________________________________________
___________________________________________________________
(2 marks)
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ii.
Cl2 + 2NaBr
2NaCl + Br2
___________________________________________________________
___________________________________________________________
___________________________________________________________
(2 marks)
3b. Write the ionic equation of this reaction, leaving out the spectator ions:
H2SO4 + Na2CO3
Na2SO4 + H2O + CO2
___________________________________________________________
___________________________________________________________
___________________________________________________________
(2 marks)
c.
Calculate the oxidation number of chromium in each of the following:
i.
Cr2O3 _____________________________________________________
ii.
Na2Cr2O7 __________________________________________________
iii.
CrSO4 ______________________________________________________
iv.
CrO42- _____________________________________________________
(4 marks)
(Total: 10 marks)
4a. From the list of elements provided below give the name of the most
reactive element and the name of the least reactive element:
calcium
copper
aluminium
iron
sodium
gold
i. the name of the MOST reactive element __________________________
ii. the name of the LEAST reactive element __________________________
(2 marks)
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bi. The MOST reactive element from the list above is one of the most difficult
elements to extract. Give reasons for this.
___________________________________________________________
___________________________________________________________
(1 marks)
ii. Gold has been known and used for thousands of years longer than
aluminium. Explain why.
___________________________________________________________
(1 mark)
c. In this question the activity of calcium and copper are compared.
i. Write below the equation of the reaction of calcium with dilute hydrochloric
acid if any reaction takes place. If no reaction takes place write
“No Reaction.”
___________________________________________________________
(2 marks)
ii. Write below the equation of the reaction of copper with dilute hydrochloric
acid if any reaction takes place. If no reaction takes place write
“No Reaction.”
___________________________________________________________
(2 marks)
d. Write an equation to show the reaction that occurs when some iron
filings are added to copper nitrate solution. You are also to include the
state of each substance.
__________________________________________________________
(2 marks)
(Total: 10 marks)
5. This question is about the Group VII elements, the Halogens:
Fluorine, chlorine, bromine and iodine.
a. Write down the electronic configuration and the states of the following
elements at room temperature:
i. fluorine: configuration - _________________ state: ________________
ii. chlorine: configuration - _________________ state: ________________
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(4 marks)
b. Does the reactivity of the halogens increase or decrease down the group?
____________________________________________________________
(1 mark)
c. When chlorine water is added to a colourless solution of potassium iodide,
the solution turns red-brown. Write a balanced equation for this reaction
and explain what happens.
____________________________________________________________
____________________________________________________________
____________________________________________________________
(2 marks)
d. The fifth element in Group VII is called astatine. It is a very rare element.
i. Do you expect it to be a gas, a liquid or a solid? Give your reason.
____________________________________________________________
____________________________________________________________
(2 marks)
ii. Do you expect astatine to be coloured or colourless?
____________________________________________________________
(1 mark)
(Total: 10 marks)
6. This question is about Group 0 elements: the noble gases.
a. Explain why the noble gases are unreactive.
___________________________________________________________
(1 mark)
b. What do a Neon atom and a sodium ion have in common? Explain
your answer.
____________________________________________________________
____________________________________________________________
(2 marks)
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b. What method can be used to separate the noble gases from the air?
___________________________________________________________
(2 mark)
c. What are the trends in density and boiling point for the noble gases,
going down the group?
___________________________________________________________
___________________________________________________________
(2 marks)
d. The sixth element in Group 0 is radon (Rn). Would you expect it to be
heavier or lighter than xenon?
___________________________________________________________
(1 mark)
e. Mention two uses of the noble gases.
____________________________________________________________
____________________________________________________________
(2 marks)
(Total: 10 marks)
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SECTION B:
Answer ANY TWO questions from this section, in the spaces provided. This
section carries 40 marks.
7a. This question is about electrolysis of dilute sulfuric acid. This experiment
is carried out using Hofmann’ s voltameter.
i. Draw Hofmann’ s voltameter in the space provided below; label the
two electrodes and the two products.
(5 marks)
ii. Which positive and negative ions are present in solution?
___________________________________________________________
(2 marks)
iii. Write the half equation which takes place at the cathode.
___________________________________________________________
(2 marks)
iv. Write the half equation which takes place at the anode.
____________________________________________________________
(2 marks)
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v. What is the ratio of the volume of product produced at the cathode to the
volume of product produced at the anode?
____________________________________________________________
(1 mark)
vi. Which two tests can be performed to confirm the nature of the products at
the cathode and the anode?
___________________________________________________________
___________________________________________________________
(2 marks)
7b. This question is about the electrolysis of copper (II) sulfate solution.
Below is a diagram of the apparatus used to carry out electrolysis of
this solution using inert (carbon) electrodes.
i. Write the two half equations that occur at the electrodes of the electrolysis
of copper (II) sulfate using carbon electrodes.
___________________________________________________________
___________________________________________________________
(4 marks)
ii. Describe and explain the change in colour and pH of the solution.
____________________________________________________________
____________________________________________________________
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(2 marks)
(Total: 20 marks)
8. This question is about extraction of important metals from their ore.
a. The first part is about extraction of aluminium. Below is the tank used for
its electrolysis:
i. What is the name of the aluminium oxide ore?
____________________________________________________________
(1 mark)
ii. What is the function of molten cryolite?
____________________________________________________________
(1 mark)
iii. Give the balanced equation for the extraction and the half equations which
occur at the cathode and at anode:
the equation: ________________________________________________
at the cathode: ________________________________________________
at the anode:
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(6 marks)
iv. Explain why the carbon anodes must be regularly replaced?
____________________________________________________________
(1 mark)
v. Aluminium Oxide is electrolysed for 2 hours using a steady current of
6000A. Find the mass of Aluminium formed. (RAM of Al=27 and 1 Faraday =
96500C)
____________________________________________________________
____________________________________________________________
____________________________________________________________
(3 marks)
8b. This part is about the extraction of iron from its ore, iron (III) oxide.
i.
What is the ore called?
__________________________________________________________
(1 mark)
ii.
What equipment is used for the extraction of iron?
___________________________________________________________
(1 mark)
iii.
A mixture called the charge is added from the top of the equipment. The
charge contains three substances; list these three substances below:
___________________________________________________________
___________________________________________________________
___________________________________________________________
(3 marks)
iv.
Write the 3 important chemical equations of the three stages in the
process:
___________________________________________________________
___________________________________________________________
___________________________________________________________
(3 marks)
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(Total: 20 marks)
9a. This question is about metals in groups 1 and 2 of the periodic table and
their compounds.
i.
What is the other name of the Group I elements?
__________________________________________________________
(1 mark)
ii.
Group I elements show a trend in melting points, does the melting point
of the elements increase or decrease going down the group?
__________________________________________________________
(1 mark)
iii. Give an equation, including state symbols of the reaction of sodium with
water.
___________________________________________________________
(2 marks)
iv. How would you describe the reaction mentioned above? Include at least
two observations that you would make.
___________________________________________________________
___________________________________________________________
(2 marks)
v. What simple test would you use to test the nature of the solution in (iii)?
__________________________________________________________
(1 mark)
vi. When potassium reacts with water, the products are the same. Explain
why it is impossible to collect the gas evolved in this reaction.
__________________________________________________________
__________________________________________________________
(1 mark)
vii. The reactivity of Group I metals, increases down the group, explain
why?
__________________________________________________________
__________________________________________________________
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__________________________________________________________
(3 marks)
viii.
Give two properties of alkali metals.
_________________________________________________________
_________________________________________________________
(2 marks)
9b. Group 2 metals are known as the Alkali-Earth metals.
i. Name two properties of the alkali earth metals.
__________________________________________________________
__________________________________________________________
(2 marks)
ii. Write the equation of the reaction that occurs when Magnesium burns in
air.
__________________________________________________________
(2 marks)
iii. Write the equation of the reaction of Magnesium with dilute sulfuric acid.
_________________________________________________________
(2 marks)
iv. Compounds of group 2 elements are very important. Amongst these
products is limestone which is found in maltese rocks. Write the
chemical formula of this compound.
_________________________________________________________
(1 mark)
Total: 20 marks)
---- END OF PAPER ---
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