2014 Senior External Examination
Chemistry
Friday 7 November 2014
Paper One — Question and response book
Time allowed
• Perusal time: 10 minutes
• Working time: 2 hours 30 minutes
Examination materials provided
• Paper One — Question and response book
• Paper One — Resource book
• Paper One Part A — Multiple-choice response sheet
9 am to 11:40 am
Candidate use
Print your candidate number here
1 4 –
–
Attach barcode here
Equipment allowed
• QCAA-approved equipment
• non-programmable calculator
Directions
Do not write in this book during perusal time.
Paper One has two parts:
• Part A — Knowledge of subject matter:
Section 1 — Multiple choice (attempt all questions)
Section 2 — Short response (attempt all questions)
• Part B — Scientific processes (attempt four questions only)
Number of books used
Supervisor use only
Supervisor’s initials
QCAA use only
Marker number
Suggested time allocation
• Part A: 1 hour 50 minutes
• Part B: 40 minutes
Assessment
Paper One assesses the following assessment criteria:
• Knowledge of subject matter
• Scientific processes
Assessment standards are at the end of this book.
After the examination session
The supervisor will collect this book when you leave.
For all Queensland schools
Planning space
Part A — Knowledge of subject matter
Part A assesses knowledge of subject matter and its simple application based on the eight topics
in the Chemistry Senior External Syllabus 1998 (amended 2006).
Part A is worth 80 marks.
Suggested time allocation: 1 hour 50 minutes.
Section 1 — Multiple choice
Section 1 has 10 questions worth 1 mark each. Attempt all questions.
Each question contains four options. Select the option that you think is correct or is the best
option. Respond on the multiple-choice response sheet.
Question 1
Which of the following is a correct classification?
Element
Compound
Mixture
A
air
carbon dioxide
copper sulfate
B
nitrogen
steel
sodium chloride
C
helium
iron ore
tap water
D
distilled water
diamond
the ocean
Question 2
The production of nitrous oxide, NO, proceeds according to the equilibrium equation:
4NH 3  g  + 5O 2  g 
4NO  g  + 6H 2 O  g 
H = – 907 kJ
Which of the following would favour the production of a high yield of NO?
A
low pressure, removal of NO
B
low pressure, high temperature
C
high pressure, low temperature
D
oxygen addition, high temperature
1
Question 3
The molecule represented by the structural formula below is the alarm pheromone produced by honey
bees.
CH3
O
CH CH2 CH2 O C CH3
CH3
This molecule could be classified as
A
an ester.
B
a ketone.
C
an alkane.
D
a carboxylic acid.
Question 4
The element magnesium has an atomic mass of 24.3. This means
A
each atom of magnesium weighs 24.3g.
B
one magnesium atom is four times as heavy as one carbon atom.
C
each atom of magnesium has a mass of exactly 24.3 atomic mass units.
D
one magnesium atom is about 24 times as heavy as one hydrogen atom.
Question 5
The formula for strontium iodate is Sr(IO3 )2 . What would be the formula for sodium iodate?
A
NaIO3
B
Na(IO3 )2
C
Na2 IO3
D
Na2 (IO3 )2
2
Question 6
A section of the periodic table has had the chemical symbols replaced by letters.
Q
R
S
T
Which element is most likely to exist as a lattice structure held together by covalent bonds?
A
Q
B
R
C
S
D
T
Question 7
Which of the following substances would you expect to be the least soluble in water?
N
A
ammonia
H
B
hydrogen chloride
H
C
chlorine dioxide
O
H
H
Cl
Cl
O
Cl
D
C
carbon tetrachloride
Cl
Cl
Cl
3
Question 8
As a person dives into the sea the pressure of gas in their lungs changes from 100 kPa to 150 kPa.
If their lungs initially held 6 L of gas, what is the new volume at constant temperature?
A
3L
B
4L
C
6L
D
9L
Question 9
The following energy profile relates to the two reactions:
2Cu  s  + O 2  g   2CuO  s 
H = –312 kJ
1
2
2Cu  s  + - O 2  g   Cu 2 O  s 
H = –170 kJ
2Cu  s  + O  g 
2
______________________
H = – 170 kJ
1
2
____________________________
Cu 2 O  s  + - O 2  g 
enthalpy
H = – 312 kJ
2CuO  s 
__________________________________________
What is the value of H kJ for the reaction below?
1
2
2CuO  s   Cu 2 O  s  + - O  g 
A
+284
B
+142
C
–142
D
–284
4
2
Question 10
An electrochemical cell was set up as shown in the diagram below.
connecting wire
zinc electrode
lead electrode
salt bridge
zinc nitrate solution
lead nitrate solution
For the cell shown,
A
there will be no electron flow in the wire.
B
electrons will flow from the lead electrode to the zinc electrode.
C
electrons will flow from the zinc electrode to the lead electrode.
D
electrons will flow through the salt bridge between the two solutions.
End of Section 1
5
Section 2 — Short response
Section 2 has eight questions worth 70 marks in total. Attempt all questions.
Write your responses in the spaces provided. Show all working.
If you need more space for a response, continue at the back of this book. Label any continued
response with the question number.
Question 11 — Materials: Properties, bonding and structure
a.
Explain the following terms:
i.
electron shell
......................................................................................................
......................................................................................................
......................................................................................................
(1 mark)
ii. electron configuration
......................................................................................................
......................................................................................................
......................................................................................................
(1 mark)
b.
Naturally occurring chlorine exists as the two isotopes
35 Cl
17
and
37 Cl
.
17
This indicates that the two nuclei of chlorine have:
i.
the same ...........................................................................................
ii. different
...........................................................................................
(1 mark)
c.
Explain why CO2 vaporises at –78.5 °C while SiO2 melts at 1700 °C.
..........................................................................................................
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(2 marks)
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d.
Draw Lewis diagrams for the following molecules and give the shape of each molecule.
Molecule
Lewis diagram
Shape of molecule
BF3
C2 H 2
(2 marks)
e.
The diagrams below represent four different types of substances.
A.
C.
B.
D.
Match the diagram with the type of substance.
Metal
..............................
Ionic solid
..............................
Covalent network solid
..............................
Covalent molecular solid
..............................
(2 marks)
f.
Give the formula for the hydrogen carbonate ion.
...................................................................
g.
(1 mark)
Name the substance that is represented by the formula P2 O3 .
...................................................................
(1 mark)
7
Question 12 — Reacting quantities and chemical analysis
a.
Explain the following term:
mass spectroscopy parent ion
..........................................................................................................
..........................................................................................................
..........................................................................................................
(1 mark)
b.
Balance the following equation:
Na 3 PO 4  aq  + Pb  NO 3  2  aq   NaNO3  aq  + Pb 3  PO 4  2  s 
(2 marks)
c.
Calculate:
i.
the mass of 0.1 moles of sodium chloride
......................................................................................................
......................................................................................................
......................................................................................................
(1 mark)
ii. the molar mass of a gas which has a density of 1.95 g L– 1 at STP.
......................................................................................................
......................................................................................................
......................................................................................................
......................................................................................................
(1 mark)
8
d.
A student is given a 1.0 L bottle which contains a 6.0M solution. How would she prepare a
250 mL sample of 0.8M concentration?
..........................................................................................................
..........................................................................................................
..........................................................................................................
..........................................................................................................
..........................................................................................................
(2 marks)
e.
Ammonia can be prepared by the following reaction:
N 2  g  + 3H 2  g   2NH 3  g 
How many litres of ammonia will be produced if 1.0 L of nitrogen is reacted with excess
hydrogen?
..........................................................................................................
..........................................................................................................
..........................................................................................................
..........................................................................................................
..........................................................................................................
(2 marks)
f.
The world’s oceans are estimated to contain 1.5 x 102 1 L of water. If 5.0 moles of sugar were
distributed uniformly throughout the oceans, how many of these sugar molecules would be in a
cup of seawater (250 mL)?
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(2 marks)
9
Question 13 — Oxidation and reduction
a.
Explain the following term:
anode
..........................................................................................................
..........................................................................................................
(1 mark)
b.
Determine the oxidation number of Mn in KMnO4 .
...................................................................
c.
(1 mark)
Identify the oxidising agent in the following chemical reaction. Explain your choice.
–
+
Cu  s  + NO 3  aq  + H  aq 
 Cu
2+
 aq  + NO 2  g  + H 2 O  g 
..........................................................................................................
..........................................................................................................
..........................................................................................................
..........................................................................................................
(1½ marks)
d.
Draw a labelled diagram to describe the chemical processes involved in obtaining pure copper
from an impure sample. Include equations in your response.
(2 marks)
10
e.
A galvanic cell was set up as shown in the diagram below. A piece of copper and a piece of
platinum were placed in a solution of CuC12 (aq) and connected by a wire. Chlorine gas was
bubbled through the solution over the piece of platinum.
.
Pt
Cu
Cl2 gas
2+
Cl–
Cu
i.
Identify the anode in the above cell. Explain your response.
.....................................................................................................
.....................................................................................................
.....................................................................................................
(1½ marks)
ii. Calculate the potential difference of the above cell.
.....................................................................................................
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.....................................................................................................
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(1 mark)
11
Question 14 — Organic chemistry
a.
Explain the following terms:
i.
functional group
......................................................................................................
......................................................................................................
......................................................................................................
(1 mark)
ii. elimination polymerisation
......................................................................................................
......................................................................................................
......................................................................................................
(1 mark)
b.
Name the organic substance with the following structure.
H
O C
H 3C C
CI
CH
CH2 CH2 CH3
CI
..........................................................................................................
(1 mark)
c.
A student incorrectly named the following two compounds. Write the correct names according to
the IUPAC naming system.
Incorrect name
i.
IUPAC name
3,3–dimethyl–4–methylpentane
ii. 2–ethylpropane
(2 marks)
12
d.
Complete the following table.
General formula
Structure which contains
four carbon atoms
carboxylic acids
amines
(2 marks)
e.
A student is given an organic compound that is either an alkane or an alkyne. State a test and
subsequent results that could be used to classify the compound.
..........................................................................................................
..........................................................................................................
..........................................................................................................
..........................................................................................................
(1 mark)
13
Question 15 — Chemical periodicity
a.
On the diagram below, identify the s, p, d and f block groups of elements.
(2 marks)
b.
Name an element which:
i.
has a half-full s subshell in its ground state electron configuration
.....................................................................................
ii. requires 3 additional electrons to obtain a full outer shell
.....................................................................................
iii. has a very low first ionisation energy
.....................................................................................
iv. forms an acidic oxide
.....................................................................................
v.
has the same group number and period number
.....................................................................................
vi. is similar chemically to the element with ten electrons
.....................................................................................
(3 marks)
c.
Explain the trend in atomic radius displayed by the period 2 elements of the periodic table.
.....................................................................................
.....................................................................................
(1 mark)
14
Question 16 — Gases and the atmosphere
a.
Describe, using the particle theory, what happens when an air hose is used to inflate a bicycle tyre.
..........................................................................................................
..........................................................................................................
..........................................................................................................
(1 mark)
b.
Explain the concept of vapour pressure and one factor on which it depends.
..........................................................................................................
..........................................................................................................
..........................................................................................................
(1 mark)
c.
8.4 g of nitrogen gas is present in a sealed 1.5 L container which is held at a temperature of 40 °C.
What pressure is exerted?
..........................................................................................................
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(2 marks)
15
d.
500 mL of nitrogen gas is collected over water at 25 °C at a pressure of 100.6 kPa.
N2(g)
delivery tube
H20
The nitrogen gas is not pure but is mixed with water vapour which exerts a vapour pressure of
2.8 kPa at that temperature. Find the volume that nitrogen alone would occupy if the conditions
were at STP.
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(2 marks)
16
Question 17 — Energy and rates of chemical reactions
a.
Define the following terms:
i.
exothermic reaction
.....................................................................................................
.....................................................................................................
.....................................................................................................
(1 mark)
ii. reaction mechanism
.....................................................................................................
.....................................................................................................
.....................................................................................................
(1 mark)
Gases A and B react to form gas C according to the reaction coordinate diagram below.
100
Potential energy
(kJ/mol)
b.
0
i.
Reaction coordinate
Is the reaction exothermic or endothermic? Explain your response.
.....................................................................................................
.....................................................................................................
.....................................................................................................
(1 mark)
ii. Would you expect this reaction to occur rapidly at room temperature? Explain your response.
.....................................................................................................
.....................................................................................................
.....................................................................................................
(1 mark)
iii. Suggest a method by which the reaction rate could be increased.
.....................................................................................................
.....................................................................................................
(1 mark)
17
c.
As a substance melts its temperature remains constant, even though heat is still being applied.
Describe the energies involved in the phase change.
..........................................................................................................
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..........................................................................................................
..........................................................................................................
..........................................................................................................
(1 mark)
d.
Use the standard enthalpies of formation to calculate the enthalpy change associated with the
decomposition of calcium carbonate,
CaCO 3  s   CaO  s  + CO 2  g 
Substance
H °f (kJ mol– 1 )
CaCO3 (s)
–1207
llllCaO(s)
–636
lllCO2 (g)
–393
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(2 marks)
18
Question 18 — Chemical equilibrium
a.
Consider a gas-fuelled bunsen burner producing a constant amount of heat. Has equilibrium been
established? Explain.
..........................................................................................................
..........................................................................................................
..........................................................................................................
(1 mark)
b.
i.
Use the Lowry–Brönsted theory of acids and bases to define an acid.
.....................................................................................................
.....................................................................................................
(1 mark)
ii. Use the Lowry–Brönsted theory to identify the conjugate acid-base pairs in the following
equation.
–
HSO 4  aq  + NH 3  g 
2–
+
SO 4  aq  + NH 4  aq 
(1 mark)
c.
i.
List two physical properties of acids.
.....................................................................................................
.....................................................................................................
(1 mark)
ii.
Describe a chemical reaction of bases.
.....................................................................................................
.....................................................................................................
(1 mark)
d.
Determine the pH of a solution which contains 1 x 10– 9 moles of OH– ions in a volume of 0.5 L.
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(2 marks)
19
e.
The Ksp of BaCO3 at 25 °C is 8.1 x 10– 9 . Calculate the mass (in grams) of barium carbonate that
will dissolve in 0.5 L of solution at 25 °C.
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(2½ marks)
f.
The following equilibrium is established by reacting PC13 (g) and Cl2 (g) in a closed container.
PCl 3  g  + C l 2  g 
PCl 5  g 
The initial concentrations of PCl3 (g) and Cl 2 (g) are both 2.0M and the concentration of PCl5 (g)
is found to be 0.5M when equilibrium is established.
Find the value of the equilibrium constant.
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(2½ marks)
End of Section 2
End of Part A
20
Part B — Scientific processes
Part B assesses scientific processes based on the eight topics in the Chemistry Senior External
Syllabus 1998 (amended 2006) and practical work undertaken during your study of the subject.
Part B has five questions of equal value. Attempt four questions only. If you respond to all five
questions, only your first four responses will be assessed.
Write your responses in the spaces provided.
Suggested time allocation: 40 minutes.
Question 1 — Materials: Properties, bonding and structure
A student leaves a solution unlabelled in the laboratory. It is known to contain one of the following
cations: Pb2 + , Sr2 + , Ba2 + , Mg2 + , or Ca2 + .
He then tests samples of the unknown solution with 1.0M solutions of Na2 SO4 , NaCl and NaOH, to
obtain the following results:
Test
the SO 4
2–
solution is added
Result
a white precipitate forms
the Cl– solution is added
a white precipitate forms
the OH– solution is added
a white precipitate forms
Use the information provided above and the resource book to determine which cation is present in the
unknown solution. Fully explain your reasoning.
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21
Question 2 — Gases and the atmosphere
Below are the rough laboratory notes of a chemistry student investigating the relationship between
volume and pressure of a gas.
R .T
* 40. 0 kPa 61. 9 mL
23.ºC
* 100.0 kPa 29.0 mL
* 50. 0 kPa 49. 8 mL
V of Flask
* 130. 0 kPa
19. 0 mL
syringe
kPa
* 118.0
21.0 mL
* 106. 0 kPa
kPa
* 75.0
L
33.0 m
23. 3 mL
a.
Organise the data from the investigation into a table.
b.
On the graph paper provided on the next page, plot a graph of pressure against volume.
c.
Identify any anomalous data by circling the data point on the graph.
d.
Use the graph to determine the volume of the apparatus when the pressure was 120.0 kPa.
22
23
Question 3 — Energy and rates of chemical reactions
The reaction of solid calcium carbonate with hydrochloric acid can be described by the equation:
CaCO 3  s  + 2HCl  aq   CaCl 2  aq  + CO 2  g  + H 2 O  l 
The rate of this reaction can be studied by continuously measuring the mass of the reaction mixture in
an open vessel.
Case X deals with 10.0 g of small calcium carbonate crystals with a 200.0 g solution containing
0.25 mol of hydrochloric acid.
Case Y deals with 10.0 g of large calcium carbonate crystals with a 200.0 g solution containing
0.25 mol of hydrochloric acid.
The results of the experiments are displayed in the following graph:
Mass (grams) of contents of flask
210
208
Case Y
Case X
206
0
a.
2
4
Time (minutes)
6
8
Explain why this method can be used to follow the rate of the reaction.
..........................................................................................................
..........................................................................................................
b.
Which reactant is in excess? Explain your response.
..........................................................................................................
..........................................................................................................
..........................................................................................................
c.
What effect does crystal size have on the rate of reaction? Explain your response.
..........................................................................................................
..........................................................................................................
..........................................................................................................
d.
Suggest a method for following the rate of reaction if the flask was closed.
..........................................................................................................
..........................................................................................................
24
Question 4 — Reacting quantities and chemical analysis
Sulfuric acid reacts with ‘thio’ (sodium thiosulfate) producing a precipitate of sulfur. Samples of
10 mL of 0.1M thio were placed in similar tubes and varying quantities of 0.2M acid were added. The
sulfur precipitate was allowed to settle and its depth measured.
The results are given below.
Volume of 0.2M H2 SO4 added (mL)
1
3
5
7
9
11
Depth of precipitate (mm)
1
3
5
4.5
5
5
In what molar proportions do thio and acid react? Explain your response.
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25
Question 5 — Chemical equilibrium
Carbon monoxide reacts with fluorine to produce carbon oxyfluoride as shown in the equation:
CO  g  + F 2 g 
COF 2 g 
A scientist studying this reaction measured the concentration of each of these gases in a sealed
2.0 L reaction vessel over a period of time. The results are shown below.
0.5
COF2
Concentration (mol L–1 )
COF2
0.4
F2
0.3
F2
0.2
CO
0.1
CO
0.0
0
a.
5
10
15
20
25
30
35
40
Time (minutes)
At what time did the reaction first reach equilibrium?
..........................................................................................................
b.
What change was made by the scientist at t = 15 minutes? Explain the variation in concentration
of the three substances.
..........................................................................................................
..........................................................................................................
..........................................................................................................
..........................................................................................................
c.
At t = 30 minutes, the temperature of the reaction vessel was decreased. Is the reaction
exothermic or endothermic? Explain.
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End of Part B
End of Paper One
26
Additional response page
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29
Very High Achievement
Scientific
processes
A very high ability to succeed in
simple scientific process tasks —
collecting and organising data,
processing information, making
simple judgments,
communicating information in
various contexts, devising and
designing simple and/or
single-step investigations.
Knowledge of A very high ability to recall and
subject
apply knowledge of chemistry in
matter
simple situations.
Criteria
Sound Achievement
A high ability to succeed in
simple scientific process tasks —
collecting and organising data,
processing information, making
simple judgments,
communicating information in
various contexts, devising and
designing simple and/or
single-step investigations.
Very Limited Achievement
Very limited ability to succeed in
simple scientific process tasks.
Limited ability to recall and apply Very limited ability to recall and
knowledge of chemistry in simple apply knowledge of chemistry in
situations.
simple situations.
Limited Achievement
A satisfactory ability to succeed Limited ability to succeed in
in simple scientific process tasks simple scientific process tasks.
— collecting and organising data,
processing information, making
simple judgments,
communicating information in
various contexts, devising and
designing simple and/or
single-step investigations.
A high ability to recall and apply A satisfactory ability to recall and
knowledge of chemistry in simple apply knowledge of chemistry in
situations.
simple situations.
High Achievement
Paper One
Assessment standards from the Chemistry Senior External Syllabus 1998 (amended 2006)
© The State of Queensland (Queensland Curriculum and Assessment Authority) 2014
Copyright protects this material. Copyright in the Senior External Examination is owned by the State of Queensland and/or the
Queensland Curriculum and Assessment Authority. Copyright in some of the material included in the paper is owned by third parties.
Except as permitted by the Copyright Act 1968 (Cwlth), reproduction by any means (photocopying, electronic, mechanical, recording
or otherwise), making available online, electronic transmission or other publication of this material is prohibited without prior written
permission of the relevant copyright owner/s.
The Queensland Curriculum and Assessment Authority requires to be recognised as the source of the Senior External Examination and
requires that its material remain unaltered.
Enquiries relating to copyright in this material, which is owned by the State of Queensland or the Queensland Curriculum and
Assessment Authority, should be addressed to:
Manager
Publishing Unit
Email: [email protected]
Queensland Curriculum
& Assessment Authority
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Level 7, 154 Melbourne Street, South Brisbane
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