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Chemistry – Form 5 Secondary – Track 3 – 2014 Page 1 of 11
DIRECTORATE FOR QUALITY AND STANDARDS IN EDUCATION
Curriculum Management and eLearning Department
Educational Assessment Unit
Annual Examinations for Secondary Schools 2014
FORM 5 CHEMISTRY TIME: 1h 45min
Name: _________________________ Class: _______________
Useful Data: Atomic numbers and relative atomic masses are shown in the periodic table printed below.
One mole of any gas occupies 22.4 dm3 at standard temperature and pressure.
Faraday constant = 96500 C mol-1
Q =It
PERIODIC TABLE
1 2 3 4 5 6 7 0
1
1H
4
2He
7
3Li
9
4Be
11
5B
12
6C
14
7N
16
8O
19
9F
20
10Ne
23
11Na
24
12
Mg
27
13Al
28
14Si
31
15P
32
16S
5.35
17Cl
40
18Ar
39
19K
40
20Ca
45
21Sc
48
22Ti
51
23V
52
24Cr
55
25Mn
56
26Fe
59
27Co
59
28Ni
5.63
29Cu
65
30Zn
70
31Ga
73
32Ge
75
33As
79
34Se
80
35Br
84
36Kr
85
37Rb
88
38Sr
89
39Y
91
40Zr
93
41Nb
96
42Mo
99
43Tc
101
44Ru
103
45Rh
106
46Pd
108
47
Ag 112
48Cd
115
49In
119
50Sn
122
51Sb
128
52Te
23
11Na
127
53I
23
11Na
131
54Xe
133
55Cs
223
87Fr
137
56Ba
139
57La
178
72Hf
181
73Ta
184
74W
186
75Re
190
76O s
192
77Ir
195
78Pt
197
79Au
201
80
Hg
204
81Tl
207
82Pb
209
83Bi
210
84Po
210
85At
222
86Rn
Key a
bX
relative atomic mass
symbol
atomic number
Marks Grid [ For Examiner’s use only ]
Question
No.
Section A Section B
1 2 3 4 5 6 7 8 9
Max
Mark 10 10 10 10 10 10 20 20 20
Theory
Total
Actual
Mark
Theory Paper: 85% Practical: 15% Final Score: 100%
Track 3
Page 2 of 11 Chemistry – Form 5 Secondary – Track 3 – 2014
SECTION A – Answer ALL questions. This section carries 60 marks.
1 This question is about carbon and its compounds. Match each of the following carbon-
containing substances with the correct description. Each substance can only be used once.
carbon monoxide calcium carbonate carbonic acid
carbon dioxide soot graphite
diamond methane coke
carbon
Description Substance
a. Fine solid particles emitted in the smoky exhaust of engines in
which the fuel is not burnt completely
b. A form of carbon that conducts electricity
c. Substance formed when carbon dioxide gas reacts with water
d. An element that is found in group 4 of the periodic table
e. It is the main component of limestone
f. A form of carbon that is burnt in the blast furnace to obtain a
high temperature
g. Poisonous gas produced when fuels are burnt in a limited supply
of air
h. A form of carbon that is transparent and very hard
i. A gas produced from the complete combustion of fossil fuels
j. A gas which burns easily and is commonly used as a fuel
[10]
2 Use the periodic table on the first page of the exam paper to help you answer this question.
Near each statement write the symbol of an element that corresponds to the description.
Description Symbol Description Symbol
[10]
a. A transition metal f. A halogen
b. An alkali metal g. An alkali earth metal
c. The element made of the smallest
atoms
h. The most reactive metal in the
third row (period 3)
d. An element that has 5 outer shell
electrons
i. The most reactive non-metal in
the third row (period 3)
e. A non-metal that has 6 outer shell
electrons and 3 electron shells
j. The most unreactive element in
the third row (period 3)
Chemistry – Form 5 Secondary – Track 3 – 2014 Page 3 of 11
3 Jason decided to investigate the order of reactivity of 4 metals with dilute sulfuric acid. The
acid he used had a molar concentration of 0.5 mol dm-3
.
He tested the following metals:
aluminium zinc iron magnesium
He noted that in all four test-tubes, bubbles of gas were formed, as shown in the picture
below.
a. (i) Using your knowledge of the activity series of metals, predict which metal corresponds
to each test-tube reaction in the diagram.
Reaction A Reaction B Reaction C Reaction D
[2]
Metal
(ii)
Write a balanced chemical equation, including state symbols, to represent the
reaction of magnesium with dilute sulfuric acid.
_______________________________________________________________________ [3]
b. (i) Mention two ways of ensuring that the testing of all four metals with the acid is ‘fair’.
_______________________________________________________________________
_______________________________________________________________________
[2]
(ii) Explain why it would not be a good idea to use sodium metal for this type of experiment.
______________________________________________________________________ [1]
(iii) Jason tested the gas produced with a burning splint and in each case, it burnt with a pop
showing that it is hydrogen. Write a balanced chemical equation to represent this
reaction.
_______________________________________________________________________
_______________________________________________________________________
[2]
Page 4 of 11 Chemistry – Form 5 Secondary – Track 3 – 2014
4 Martina, a chemistry student, sets up the apparatus shown below in order to prepare a dry
gas. Dilute hydrochloric acid solution is placed in the dropping funnel and potassium
sulfite powder in the reaction flask. The tap of the dropping funnel is opened to allow the
dilute hydrochloric acid to pour onto the potassium sulfite. The tap is immediately closed.
a. (i) Write the names corresponding to the diagram labels A, B, C and D:
A_____________________________ B_____________________________
C_____________________________ D_____________________________
[2]
(ii) Write a balanced chemical equation showing the reaction of dilute hydrochloric acid
with potassium sulfite.
_______________________________________________________________________ [2]
(iii) Which gas is being prepared in this experiment?
_______________________________________________________________________ [1]
b. (i) Martina was going to use a gas syringe to collect the gas but unluckily, the only syringe
available in her lab broke. On the diagram draw and label an alternative piece of
equipment that can be used to collect the gas. Name the collecting technique used and
explain why you chose it.
_______________________________________________________________________
_______________________________________________________________________
[4]
(ii) Explain the purpose of the liquid D shown in the diagram.
_______________________________________________________________________ [1]
Chemistry – Form 5 Secondary – Track 3 – 2014 Page 5 of 11
5 Cracking is an important part of the crude oil refining process. Luke decided to try cracking
on a small scale in the chemistry laboratory by using the apparatus shown below. He used the
compound decane as the ‘long-chained hydrocarbon’ to be cracked.
a. (i) What is the role of aluminium oxide or broken porcelain in this experiment?
_______________________________________________________________________ [1]
(ii) Explain why cracking is used in the oil industry.
_______________________________________________________________________
_______________________________________________________________________
[2]
b. The equation below represents the reaction that occurs when decane is cracked:
C10H22 → C8H18 + C2H4
(i) Write the chemical name of the two products.
C8H18_________________________________________________________________
C2H4__________________________________________________________________
[2]
(ii) Write A on the diagram above where you would expect C2H4 to be collected and write B
where you would expect C8H18 to be collected. [2]
c. (i) C8H18 belongs to the family of compounds (homologous series) known as alkanes. To
which series does C2H4 belong?
_______________________________________________________________________ [1]
(ii) Draw the structures of C2H4 and C8H18.
[2]
Page 6 of 11 Chemistry – Form 5 Secondary – Track 3 – 2014
6 Nicole investigated the rate of reaction of
marble chips (calcium carbonate) with dilute
nitric acid.
She reacted 1.0 g of marble chips with
100 cm3 of 0.2 mol dm
-3 nitric acid solution
in a conical flask as shown in the diagram to
the right.
During the investigation, Nicole took
readings of the mass of the flask and
contents over a period of time.
She then plotted the results on the graph
shown below.
a. (i) Write a balanced chemical equation to represent this reaction.
_______________________________________________________________________ [2]
(ii) Explain the purpose of the cotton wool in this experiment.
_______________________________________________________________________
…this question continues on the next page…
[1]
Chemistry – Form 5 Secondary – Track 3 – 2014 Page 7 of 11
b. Use the graph on page 6 to find:
(i) The initial mass of the flask and contents.
_______________________________________________________________________
[1]
(ii) The time when the reaction stopped.
_______________________________________________________________________
[1]
(iii) The final mass of the flask and contents.
_______________________________________________________________________
[1]
c. (i) Calculate the change in mass of the flask and contents due to the reaction.
_______________________________________________________________________ [1]
(ii) Explain what caused the change in mass of the flask during this reaction.
_______________________________________________________________________ [1]
(iii) Explain which section of the graph (page 6) A, B or C represents the highest rate of the
reaction.
_______________________________________________________________________
_______________________________________________________________________
[1]
d. Nicole tried out the experiment a second time. This time she reacted 1.0 g of marble chips
with 100 cm3 of 0.4 mol dm
-3 nitric acid solution (instead of 0.2 mol dm
-3).
Sketch on the same graph on page 6 the curve you would expect her to obtain.
(Assume that the cotton wool weighed exactly like the one in the first experiment.)
[1]
Page 8 of 11 Chemistry – Form 5 Secondary – Track 3 – 2014
SECTION B – Answer TWO questions only on the foolscap provided.
This section carries 40 marks.
7 Read the newspaper passage below before answering the questions.
Arizona wildfire tragedy: 19 firefighters lose their lives
Over the parched Granite Mountains, 19 of the most well-trained and physically fit firefighters in the United States of America died while battling one of the deadliest wildfire since the 1930s. On the hot afternoon of 30 June 2013, the
firefighters had made their way to the dry area around Yarnell Hill to take on what seemed a small fire that had been triggered by lightening a day or two before. Some of the trees and shrubs were alight. But the wind suddenly blew up and changed the situation drastically. A fire that looked beatable suddenly roared to life, cutting off their escape routes.
The firefighters deployed their personal shelters, capsule-like devices
designed to deflect heat and trap breathable air, in a last-ditch effort to survive.
Some of the men made it into their shelters and some did not, according to a helicopter crew flying over the area. The helicopter crew looked on helplessly but could do nothing to help the firefighters.
19 out of the 20 firefighting squad members lost their lives.
a. (i) Burning wood from trees acted as fuel. Name another source of fuel for this wildfire. [1]
(ii) Name two products released from the complete combustion of wood, which is similar to
fossil fuels.
[2]
(iii) Briefly describe a chemical test to show the presence of each of the two products you
mentioned in a. (ii) above.
[2]
(iv) From what you read above, deduce the conditions that make a wildfire likely to start. [5]
(v) Using your knowledge of chemical reactions, explain how the wind made the fire more
dangerous.
[2]
(vi) The firefighters’ shelters were designed to ‘deflect heat and trap breathable air.’ What
two dangerous products were the firefighters exposed to?
[2]
b. (i) Wildfires contribute to world pollution. Explain the polluting effects that you would
expect wildfires to have on the environment.
[3]
(ii) Combustion of hydrocarbon fuels is an even bigger contributor to world pollution than
forest fires. Write a balanced chemical equation to represent the combustion of the
hydrocarbon octane, which is present in petrol. Include state symbols.
[3]
Chemistry – Form 5 Secondary – Track 3 – 2014 Page 9 of 11
8 Some clothes cannot be washed in water
because they would change shape or shrink.
Therefore they are taken for dry-cleaning.
Dry-cleaning is also used to remove dirt and
greasy stains that water and detergents cannot.
In dry-cleaning, special solvents (liquids) that
dissolve grease are used. A dry-cleaning
machine is like a big washing machine that
uses a solvent instead of water. The solvent is
recycled and used over and over again.
Chemists can ‘design’ dry-cleaning solvents so
that they have exactly the properties needed.
‘I should have taken my t-shirt
for dry-cleaning instead of
washing it at home!’
A dry-cleaning machine
When choosing a solvent for dry-cleaning,
chemists look at the following properties:
Whether it is flammable or not
If it is poisonous or not
Its boiling point :
o If it is too high it will prove costly
to recycle
o If it is too low it will vaporise in
the machine
a. (i) Once the clothes are removed from a dry-cleaning machine, they are ‘wet’ with the
solvent. Name the process by which the solvent can be removed from the clothes and
state two ways of making this process happen faster.
[3]
(ii) Petrol is a very volatile liquid that is very good at dissolving grease. Give two possible
reasons why it is not used as a solvent in dry-cleaning. [2]
b. The manager of a dry-cleaning business has asked you to give her some advice on which
solvent to use for a dry-cleaning machine. The table below gives you some important
properties of five solvents:
Solvent A B C D E
Ability to dissolve grease excellent very
good
very
good
excellent excellent
Does it burn (flammable)? no
no no yes no
Is its vapour poisonous? slightly
no no no no
What is its boiling point? 127 ºC
400 ºC 130 ºC 120 ºC 45 ºC
Decide which one of the five solvents would make the best choice for use in dry-cleaning and
explain your reasons for making that choice.
[6]
…this question continues on the next page…
Page 10 of 11 Chemistry – Form 5 Secondary – Track 3 – 2014
c.
You are given a sample of dry-cleaning solvent that has dissolved
impurities in it. You are asked to devise a way to purify the
solvent so that it can be recycled.
(i) Name the laboratory technique that can be used to obtain the
pure solvent from the impure solution.
[1]
(ii)
Draw a fully labelled diagram of the apparatus you would
use to obtain a sample of the pure solvent in the laboratory.
[4]
(iii) Explain the processes which are happening in each section
of the apparatus.
[4]
9 A laboratory analyst working in a Pharmaceutical
Company was given 4 reagent bottles each
containing a white substance. The old labels had
rotted away. The analyst’s job was to identify
which substance had been stored in each bottle.
The analyst carried out the following steps:
He checked the inventory of the cupboard
where the bottles had been stored and
discovered that each bottle contained a
magnesium compound.
These included:
o Magnesium sulfate (Epsom salts)
o Magnesium hydroxide (Magnesia)
o Magnesium chloride (Oral magnesium supplement)
o Magnesium bromide (Tranquilliser medicine)
He labelled the substances in the bottles A, B, C and D.
He observed the appearance of each substance and noted it.
He took a sample of each of the four substances and checked whether each was soluble in
water or not.
The results of steps 3 and 4 are shown below:
Appearance Solubility in water
Substance A white crystalline solid Dissolves in water to form a colourless
solution
Substance B white powder Dissolves in water to form a colourless
solution
Substance C white crystalline solid Dissolves in water to form a colourless
solution
Substance D white crystalline solid Does not dissolve in water
…this question continues on the next page…
Chemistry – Form 5 Secondary – Track 3 – 2014 Page 11 of 11
a (i) Explain why the analyst labelled all four substances before he started doing any tests on
them. [1]
(ii) By using the table on page 10, explain why the substance in bottle D could be identified
immediately without the need of further chemical tests. State the name of the substance
in bottle D.
[2]
(iii) Substance D can be classified as a base. What is a base? [1]
(iv) Name one substance that would react with substance D to produce a salt and water. [1]
b.
To discover which substances were stored in
bottles A, B and C, the analyst then
performed a series of chemical tests for
anions.
(i) Explain why the analyst did not need to perform any cation tests in order to reach his
goal of identifying the 3 remaining substances.
[1]
(ii) Describe two chemical tests which the analyst could perform on solutions of the
substances A, B and C in order to identify them conclusively.
Each of your 2 answers should include:
A brief description of the method
The observations which would be noted (including negative results) when the
reagent is added to substances A, B and C
The conclusion drawn from each observation
[12]
(iii) Write a balanced chemical equation for any one of the reactions you mentioned in
question b (ii) above.
[2]
