Part A – 20 marks
Attempt Questions 1-20
Allow about 30 minutes for this part
Use the multiple-choice answer sheet provided for Questions 1-20
Select the alternative A, B, C or D that best answers the question. Fill in the response
oval completely.
Sample
2+4 =
(A) 2
(B) 6
(C) 8
(D) 9
A
B
C
D
If you think you have made a mistake, put a cross through the incorrect answer and fill
in the new answer.
A
B
C
D
If you have changed your mind and have crossed out what you consider to be the
correct answer, then indicate this by writing the word correct and drawing an arrow as
follows:
correct
A
B
C
D
2018 Yearly Preliminary Chemistry Examination
Student Number
1
Consider the chemical reaction:
Zn (s) + CuSO4 (aq) → Cu (s) + ZnSO4 (aq)
Which atom undergoes a change in oxidation number (state) from 0 to +2?
(A)
Zn
(B)
Cu
(C)
S
(D)
O
2
3
When sodium reacts with water
(A)
sodium loses electrons.
(B)
hydroxide ions are produced.
(C)
hydrogen gas is produced.
(D)
all of the above occur.
Physical and chemical properties can be used to classify elements in the periodic
table. Examples of physical properties only are:
(A)
reactivity with water, melting point and colour.
(B)
state at room temperature, melting point and density.
(C)
heat of combustion, hardness and mass.
(D)
reactivity with acid, electrical conductivity and texture.
2
2018 Yearly Preliminary Chemistry Examination
Student Number
4
Which of the following correctly describes an ionic solid?
(A)
An ordered lattice structure with cations and free valence electrons
(B)
A crystalline form that is hard and has a lustre
(C)
A high melting point solid, due to its strong intermolecular bonding
(D)
A solid where the valence electrons are free to conduct charge
5
Predict the trend in reactivity of Group 1 elements when they are reacting in water.
(A)
Group 1 elements decrease in reactivity as they increase in atomic
number.
(B)
Group 1 elements increase in reactivity as they increase in atomic number.
(C)
Group 1 elements are not reactive in water as they possess full outer shells
of electrons.
(D)
Group 1 elements produce hydrogen gas when they react in water.
3
2018 Yearly Preliminary Chemistry Examination
Student Number
6
7
8
Which of the following substances contains only covalent bonds?
(A)
MgO
(B)
NH4NO3
(C)
SiO2
(D)
NaCl
Which of the alternatives below identifies the electron configuration of the cation and anion
present in the compound aluminium chloride?
Cation
Anion
(A)
1s2 2s2 2p6 3s2 3p1
1s2 2s2 2p6 3s2 3p5
(B)
1s2 2s2 2p6 3s2 3p5
1s2 2s2 2p6 3s2 3p1
(C)
1s2 2s2 2p6 3s2 3p6
1s2 2s2 2p6
(D)
1s2 2s2 2p6
1s2 2s2 2p6 3s2 3p6
A radioisotope (X) undergoes α-decay to produce radioisotope Y.
Radioisotope Y undergoes β-decay to produce actinium-228.
Which of the following identifies radioisotope X?
(A)
radium-226
(B)
uranium-238
(C)
palladium-231
(D)
thorium-232
4
2018 Yearly Preliminary Chemistry Examination
Student Number
9
Iron can react with water to produce iron oxide (Fe3O4) and hydrogen gas.
Which is the balanced equation for this reaction?
10
(A)
3Fe(s) + 4H2O(l)  Fe3O4(s) + H2(g)
(B)
3Fe(s) + H2O(l)  Fe3O4(s) + H2(g)
(C)
6Fe(s) + 4H2O(l)  2Fe3O4(s) + 6H2(g)
(D)
3Fe(s) + 4H2O(l)  Fe3O4(s) + 4H2(g)
A section of the periodic table has had the symbols for 4 elements replaced by letters, as
shown below.
Which alternative below correctly matches the elements’ letters with the blocks to which they belong
in the periodic table?
L
M
N
K
(A)
s
d
p
s
(B)
s
p
d
s
(C)
d
s
p
p
(D)
d
s
p
p
5
2018 Yearly Preliminary Chemistry Examination
Student Number
Use the following solubility rules to answer the next two questions.
All NH4+ and group I compounds are soluble
All nitrates are soluble
All chlorides are soluble except Ag+ and Pb2+
All sulfates are soluble except Pb2+ ,Sr2+ and Ba2+
All hydroxides are insoluble except Ba2+ , Sr2+ , NH4+ and group I compounds
All carbonates and phosphates are insoluble except NH4+ and group I
compounds.
11
12
Identify which of the following mixtures from A, B, C or D form a precipitate.
(A)
Sodium chloride solution and magnesium sulfate solution.
(B)
Ammonium nitrate solution and potassium carbonate solution.
(C)
Calcium chloride solution and iron (III) nitrate solution.
(D)
Copper (II) sulfate solution and sodium hydroxide solution.
When a solution of sodium carbonate was added to solution X, known to be a
soluble salt, a white solid precipitate was formed. Solution X could be
(A)
calcium nitrate.
(B)
potassium chloride.
(C)
copper sulfate.
(D)
sodium sulfate.
6
2018 Yearly Preliminary Chemistry Examination
Student Number
13
14
15
An alloy of bismuth, tin and lead is used as a coolant in nuclear reactions. This
alloy is prepared by melting together 25.44 g of bismuth, 15.36 grams of lead
and 7.20 grams of Tin. What is the percentage composition of the alloy?
(A)
25.44 % Bi, 15.36 % Pb and 7.20% Sn.
(B)
48% BiPbSn.
(C)
58% Bi, 27% Pb and 15% Sn.
(D)
53% Bi, 32% Pb and 15% Sn.
Boyle’s Law states:
(A)
That at constant pressure, the volume (V) of a fixed mass of a gas is
directly proportional to its temperature (T) in Kelvin.
(B)
That the volume (V) of a fixed mass of gas is inversely proportional to its
pressure (P) at constant temperature.
(C)
That at constant temperature and pressure, the volume (V) of a gas is
directly proportional to the number of moles (n) of the gas.
(D)
That the total pressure of a mixture of gases is equal to the sum of the
partial pressures of the individual gases.
Sodium metal reacts with chlorine gas producing sodium chloride. This reaction
is an oxidation reduction reaction. Name the species undergoing oxidation?
(A)
Sodium metal.
(B)
Chlorine gas.
(C)
Sodium ion in NaCl.
(D)
Chloride ion in NaCl.
7
2018 Yearly Preliminary Chemistry Examination
Student Number
16
17
18
Which of these equations represents the complete combustion of ethanol (C2H5OH)?
(A)
C2H5OH(l) + O2(g)  2C(s) + 3H2O(l)
(B)
C2H5OH(l) + 2O2(g)  2CO(g) + 3H2O(l)
(C)
C2H5OH(l) + 3O2(g)  2CO2(g) + 3H2O(l)
(D)
C2H5OH(l) + 2O2(g)  CO2(g) C(s) + 3H2O(l)
As you move down the elements in group 7 of the periodic table, the first ionisation
energy:
(A)
increases and the electronegativity increases.
(B)
decreases and the electronegativity increases.
(C)
increases and the electronegativity decreases.
(D)
decreases and the electronegativity decreases.
Identify the oxidation reaction from the options below.
(A)
2NO2  N2O4
(B)
CaO + H2O  Ca(OH)2
(C)
CaCO3  CaO + CO2
(D)
C + O2  CO2
8
2018 Yearly Preliminary Chemistry Examination
Student Number
19
The following reaction occurs when potassium iodide is added to a solution
containing excess lead ions:
2KI (aq) + Pb(NO3)2 (aq) → PbI2 (s) + 2KNO3 (aq)
The mass of lead iodide formed when 25 mL of a 0.421 mol/L solution of
potassium iodide is added to a solution containing excess lead ions is closest
to:
20
(A)
0.1 g
(B)
1.2 g
(C)
2.4 g
(D)
4.8 g
The following table gives the standard electrode potentials for a number of halfreactions.
Some standard potentials
Zn2+(aq) + 2e-  Zn(s)
-0.76 V
Fe2+(aq) + 2e-  Fe(s)
-0.44 V
+ 2e-  2I- (aq)
I2 (g)
Fe3+(aq) + e-  Fe2+(aq)
Ag+(aq)
+ e-  Ag(s)
0.53 V
0.77 V
0.80 V
Which substance in the above table will convert iodide ions to iodine and
produce the highest voltage?
(A)
Zn2+(aq) + 2e-  Zn(s)
(B)
Fe2+(aq) + 2e-  Fe(s)
(C)
Fe3+(aq) + e-
(D)
Ag+(aq) + e-  Ag(s)
 Fe2+(aq)
9
2018 Yearly Preliminary Chemistry Examination
Student Number
Part B – 50 marks

Attempt Questions 21–31

Allow about 1.5 hours for this part

Answer the questions in the spaces provided. These spaces provide guidance for the expected
length of response.

Show all relevant working in questions involving calculations.
Marks
Question 21 (8 marks)
The symbol for an isotope of phosphorus is:
(a)
How many protons, neutrons and electrons are present in a neutral atom of
this isotope?
1
……………………………………………………………………………………...
……………………………………………………………………………………...
(b)
Explain why the relative mass of phosphorus is 30.97 and not 31.0 exactly.
……………………………………………………………………………………...
2
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
10
2018 Yearly Preliminary Chemistry Examination
Student Number
(c)
Phosphorus and nitrogen are in the same group of the periodic table. Both
form chlorides.
Some data about their chlorides are shown in the table below.
Element
Chloride Formula
Boiling Point (oC)
Nitrogen
NCl3
71
PCl3
76
PCl5
167
Phosphorus
(i)
The reaction to form liquid PCl3 involves heating solid phosphorus in
the form of P4 with chlorine gas.
Write a balanced chemical equation for this reaction.
……………………………………………………………………………………...
(ii)
1
Complete the table below.
Formula
Systematic
name
Electron dot diagram
Molecular
shape
3
PCl3
(iii) Account for the higher boiling point of PCl5 compared to PCl3.
……………………………………………………………………………………...
1
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
11
2018 Yearly Preliminary Chemistry Examination
Student Number
Question 22 (3 marks)
A student used the following apparatus to decompose a small sample of
an oxide of copper. The purpose of the natural gas from the outlet is to
prevent any copper that forms from oxidising back into a copper ion.
The products of the decomposition are metallic copper and oxygen.
The data from the experiment are shown below.
Mass of empty test tube (g)
Mass of test tube and copper oxide powder before heating
(g)
Mass of test tube and residue after heating for 1 minute (g)
Mass of test tube and residue after heating for 2 minute (g)
Mass of test tube and residue after heating for 3 minute (g)
Mass of test tube and residue after heating for 4 minute (g)
30.43
32.73
32.58
32.34
32.23
32.23
Use the data provided to determine the empirical formula of the oxide
decomposed in the investigation.
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
12
2018 Yearly Preliminary Chemistry Examination
Student Number
Question 23 (5 marks)
Marks
Use the information in the table below to answer the following questions.
Element
Atomic Radius
Melting Point (oC)
1st Ionisation
Energy (MJ mol-1)
(10-9 m)
Na
0.154
98
0.5
Mg
0.136
650
0.7
Al
0.118
660
0.6
Si
0.111
1400
0.8
P
0.106
44
1.0
S
0.102
113
1.0
Cl
0.099
-101
1.3
Ar
0.098
-189
1.5
(a) How would the size of the chloride ion compare with the size of the chlorine atom?
Explain.
2
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
(b) Name the element from the table which would have the highest value for its
second ionisation energy?
1
……………………………………………………………………………………...
13
2018 Yearly Preliminary Chemistry Examination
Student Number
(c) State the general trend and explain the variation in atomic radii for these
elements.
1
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
(d) Why is the melting point for silicon so much higher than the other elements?
1
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
14
2018 Yearly Preliminary Chemistry Examination
Student Number
Question 24 (5 marks)
6.54 g of zinc metal was reacted with excess hydrochloric acid at 25°C and 100 kPa
pressure.
(a) Write the equation for this reaction.
Marks
1
……………………………………………………………………………………...
(b) Calculate the number of moles of hydrogen gas formed.
1
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
(c) Calculate the volume that this number of moles of hydrogen gas would occupy
at 25°C and 100 kPa pressure.
1
……………………………………………………………………………………...
……………………………………………………………………………………...
(d) Calculate the volume that this same number of moles of hydrogen gas would
occupy, if the pressure were changed to 220 kPa and the temperature were
changed to 35°C.
2
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
15
2018 Yearly Preliminary Chemistry Examination
Student Number
Question 25 (4 marks)
(a) Sodium carbonate, in a form known as soda ash, is used to remove excess acidity
in swimming pools. Having stood in an open plastic bottle for some time, 1.50 L of a
1.00 solution molL-1 of soda ash was found to have lost 0.047L of water, by
evaporation. Assume 1g of water = 1 mL of water.
Calculate the new concentration of the soda ash?
Marks
1
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
(b) Using the information in 25(a), what volume of Na2CO3 solution would need to be
added to react completely with 1.0 L of 0.20 molL-1 HCl solution?
3
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
16
2018 Yearly Preliminary Chemistry Examination
Student Number
Marks
Question 26 (3 marks)
Calculate the concentration of nitrate ions present in an 800.0 mL aqueous solution
containing 22.5 g of dissolved aluminium nitrate.
3
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
Question 27 (3 marks)
Marks
Derive and balance the following chemical equations.
(a)
Nitrogen gas reacts with hydrogen gas producing ammonia gas (NH3).
1
…………………………………………………………………………………….
(b)
Silver bromide is decomposed to silver and bromine gas.
1
…………………………………………………………………………………….
(c)
Methane gas is combusted to water and carbon dioxide gas.
1
…………………………………………………………………………………….
17
2018 Yearly Preliminary Chemistry Examination
Student Number
Question 28 (4 marks)
Use the information in the table below to answer the following question.
Property
Lithium
Sodium
Potassium
Rubidium
Electronegativity
0.98
0.93
0.82
0.82
Atomic radius
152
186
227
248
526
502
425
409
4
(picometres)
Ionisation
energy
(kJmol-1)
List the metals in the table in order of activity going from least active to most active and
describe how electronegativity, ionisation energy and atomic radius correlate with metal
activity.
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
18
2018 Yearly Preliminary Chemistry Examination
Student Number
Marks
Question 29 (7 marks)
Consider the following redox pairs and their reduction potentials (E0 values):
Zr4+/Zr
Ga3+/Ga
Au+/Au
V2+/V
Pt2+/Pt
(a)
(b)
- 1.53 V
- 0.53 V
+ 1.68 V
- 1.18 V
+ 1.20 V
Identify the species which is the:
(i)
strongest oxidant ………………………………………………….
(ii)
strongest reductant ………………………………………………...
A chemist wants to determine the cell voltage of a Galvanic cell involving
the Ni2+/Ni and Ag+/Ag redox pairs.
Draw a labelled diagram of a galvanic cell that could be constructed to
achieve this.
(c)
2
Use the standard half-cell potentials on the Data Sheet to calculate the
voltage produced by the cell.
3
2
Show all working and include the overall net ionic equation for the
reaction.
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
19
2018 Yearly Preliminary Chemistry Examination
Student Number
Marks
Question 30 (4 marks)
Michelle conducted an experiment in a laboratory to investigate the law of conservation of
mass using the masses of reactants and products and to derive the empirical formula of
zinc oxide.
To carry out this experiment she used the following materials:






150 mL conical flask and stopper
1-2g of zinc pieces
Specimen tube containing 1g solid iodine
20 mL of ethanol
Pipette
Hotplate
(a) In the space below construct a risk assessment table for this experiment.
3
(b)
Identify why a hot plate was used in this experiment
……………………………………………………………………………………...
1
……………………………………………………………………………………...
……………………………………………………………………………………...
……………………………………………………………………………………...
20
2018 Yearly Preliminary Chemistry Examination
Student Number
Marks
Question 31 (4 marks)
Steve carried out an experiment to obtain a reactivity series of metals by investigating
reactions in which metals displace other metal ions from solutions.
He carried out an experiment using the following chemicals:
Magnesium nitrate; copper sulfate; zinc sulfate; Mg metal; Cu metal and Zn metal
(a) Write a hypothesis for this experiment:
2
……………………………………………………………………………………...
……………………………………………………………………………………...
(b) Identify the order of reactivity:
2
……………………………………………………………………………………...
most reactive
least reactive
END OF EXAMINATION
21