Carlingford High School
2012
Higher School Certificate
Preliminary Examination
Chemistry
General Instructions
Total marks – 75

Reading time – 5 minutes

Working time – 2 hours
Attempt ALL questions

Board approved calculators may be
used

Write using black or blue pen

Draw diagrams using pencil
Section I – Pages 4–8
20 marks
Attempt Question 1–20
Allow about 35 minutes for this section

A data sheet and a Periodic Table
are provided

Write your student number and/or
name at the top of every page
Section II – Pages 9–19
55 marks
Attempt Questions 21–33
Allow about 1 hour 25 minutes for this section
This paper MUST NOT be removed from the examination room
STUDENT NUMBER/NAME: ……………………..
STUDENT NUMBER/NAME: ……………………..
Section I
20 marks
Attempt Questions 1–20
Allow about 35 minutes for this section
Select the alternative A, B, C or D that best answers the question and indicate your choice with a
cross (X) in the appropriate space on the grid below.
A
B
C
D
A
1
11
2
12
3
13
4
14
5
15
6
16
7
17
8
18
9
19
10
20
Page 3
B
C
D
STUDENT NUMBER/NAME: ……………………..
Section I
20 marks
Attempt Questions 1–20
Allow about 35 minutes for this section
Select the alternative A, B, C or D that best answers the question and indicate your choice with a
cross (X) in the appropriate space on the grid supplied.
1
What is the key difference between chemical and physical changes?
(A) A physical change involves a change in colour
(B)
A physical change occurs when a gas is produced
(C)
A chemical change always involves a change in state
(D) A chemical change involves a rearrangement of atoms
2
3
In which region of the Earth do the compounds of carbon, hydrogen and
oxygen dominate?
(A) The atmosphere
(B) The biosphere
(C) The hydrosphere
(D) The lithosphere
The melting points and boiling points for five common substances at 100 kPa pressure are
listed below:
Substance
P
Q
R
S
Melting point (oC)
–114
–219
327
144
Boiling point (oC)
78
–183
1740
444
Which substance is a liquid at 25oC and 100 kPa?
(A) P
4
(B) Q
(C) R
(D) S
What is the number of atoms present in 0.50 mol of ammonia molecules?
(NA is the Avogadro number).
(A) NA ÷ 2
(B)
1.5 x NA
(C)
2 x NA
(D) 4 x NA
Page 4
STUDENT NUMBER/NAME: ……………………..
5
Listed below are four compounds of copper:
CuCl2. 2H2O
Mole mass
(g)
134.4
Density
(g/cm3 )
2.5
CuF2. 2H2O
137.6
CuSO4. 5H2O
Cu(NO3)2. 6H20
Compound
green
Solubility
(g/100 g H20)
77
2.9
blue
0.07
249.7
2.3
blue
22
295.6
2.3
blue
150
Colour
What is the most useful property to separate a mixture of copper fluoride and copper
nitrate in a school laboratory?
(A) Colour
(B)
Density
(C)
Molar mass
(D) Solubility
6
In 1847 Charles Dickens praised the virtues of a newly separated metal, with the following
words.
“Within the course of the last two years ... a treasure has been divined,
unearthed and brought to light ... what do you think of a metal as white as
silver, as unalterable as gold, as easily melted as copper, as tough as iron,
which is malleable, ductile, and with the singular quality of being lighter than
glass? Such a metal does exist and that in considerable quantities on the
surface of the globe.”
Which of the following is the metal described by Dickens?
(A) Aluminium
(B)
Barium
(C)
Potassium
(D) Zinc
7
Which of the following lists the elements that are in order of increasing atomic radius?
(A) Na, Mg, P, Cl
(B)
Kr, Ar, Ne, He
(C)
Li, Be, Na, Mg
(D) F, N, B, Li
Page 5
STUDENT NUMBER/NAME: ……………………..
8
Which is the best description of ores?
(A) Crystalline compounds found in the lithosphere of the Earth
(B)
Minerals from which valuable substances can be extracted
(C)
Compounds of metals with one or more other elements
(D) Any mineral or mineral combination
9
Which process involves the breaking and making of covalent bonds between atoms?
(A) Precipitation of silver chloride
(B)
Vaporisation of water
(C)
Melting sodium chloride
(D) Electrolysis of water
10
Which of the following statements is true?
(A) Solder is an alloy of copper and nickel and it is used for making musical instruments.
(B)
Steel is an alloy of iron and gold and is used for making valuable coins.
(C)
Brass is an alloy of copper with zinc and has a shiny gold appearance.
(D) Solder is an alloy of tin and lead and has a high melting point.
11
What is the change in temperature of 1.0 kg of water when it absorbs 100 kJ of heat
energy?
(A) 0.024°C
(B)
0.42°C
(C)
24°C
(D) 42°C
12
What mass of solid zinc nitrate, Zn(NO3)2, is required to make 250 mL of a 0.10 mol L–1
aqueous solution?
(A) 0.47 g
(B)
4.7 g
(C)
19 g
(D) 190 g
Page 6
STUDENT NUMBER/NAME: ……………………..
13
What volume of water must be added to 50 mL of 1.0 mol L–1 hydrochloric acid to
produce a solution with a concentration of 0.050 mol L–1?
(A) 50 mL
(B)
250 mL
(C)
950 mL
(D) 1000 mL
14
1.000 kg of water has a volume of 1000 mL at 4.0 °C. When heated to 25.0 °C, this
volume of water expands to 1003 mL.
What is the density of water, in g mL–1, at 25.0 °C?
(A) 0.997
(B)
1.003
(C)
997
(D) 1003
15
What are the raw materials for photosynthesis?
(A) Carbon dioxide and oxygen
(B)
Carbon dioxide, water and oxygen
(C)
Carbon dioxide and water
(D) Oxygen and water
16
The apparatus shown in the diagram at right is normally used to separate
(A) Solids of different sizes
(B)
Solids and liquids
(C)
Dissolved solids in liquids
(D) Liquids
Page 7
STUDENT NUMBER/NAME: ……………………..
17
Which of the following substances are bonded by sharing electrons?
(A) Copper chloride
(B) Calcium oxide
(C) Argon
(D) Sulfur dioxide
18
Bauxite is an ore of aluminium. During the processing of bauxite, aluminium
oxide is electrolysed to form pure aluminium. Which of the following properties
of aluminium oxide allows this process to occur?
(A) It has a very high melting point
(B) It is ionic
(C) It is covalent
(D) Aluminium conducts electricity
19
A particular chemical reaction is represented by the following equation:
aN2 + bH2 → cNH3
After this reaction has been balanced, which of the following are the correct ratios
for the products and reactants?
(A)
(B)
(C)
(D)
20
a
1
2
1
2
b
3
3
2
6
c
2
1
3
2
The energy stored in the chemical bonds of fossil fuels originally came from
(A) geothermal energy
(B) solar energy
(C) the combustion of plant material
(D) the reaction of atmospheric carbon dioxide with oxygen
Page 8
STUDENT NUMBER/NAME: ……………………..
Section II
55 marks
Attempt All Questions
Allow about 1 hour and 25 minutes for this section
Answer the questions in the spaces provided.
Show all relevant working in questions involving calculations.
Question 21 (5 marks)
Marks
A chemist analysed an ionic compound containing sodium, sulfur and oxygen, and the following
percentage masses were obtained:
Sodium = 32.4 %
Sulfur = 22.5 %
Oxygen = 45.1 %
(a)
Determine the empirical formula for this compound.
3
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(b)
Explain why the formula for an ionic compound is an empirical formula.
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Page 9
2
STUDENT NUMBER/NAME: ……………………..
Question 22 (4 marks)
(a)
(b)
Marks
In the space below, draw the Lewis electron dot structures showing:
(b)
2
(i)
A chlorine molecule
A chloride ion
(i)
Metals commonly react with non-metals. Write an equation in which a chemical
reaction occurs between a metal and chlorine gas.
1
....................................................................................................................................
(ii)
Write the half-equation for the reaction that occurs with chlorine.
1
....................................................................................................................................
Question 23 (5 marks)
Marks
Some properties of the most common oxides of carbon and silicon are shown in the table.
Compound
Melting point (°C)
Solubility in water (mg L–1)
(a)
Carbon dioxide
-78 °C
1500
Silicon dioxide
1700
80
Use diagrams to contrast the bonding arrangements in these two compounds.
(b) Relate the differences in melting point and solubility to these bonding arrangements.
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Page 10
2
3
STUDENT NUMBER/NAME: ……………………..
Question 24 (4 marks)
(a)
Marks
Outline the contributions of Gay-Lussac and Avogadro to our knowledge of the
chemistry of gases.
2
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(b)
Gaseous sulfur trioxide is produced from the reaction of sulfur dioxide and oxygen gases,
as follows:
2SO2(g) + O2(g) → 2SO3(g)
(i)
Calculate the volume of oxygen required to fully react with 50.0 L of sulfur
dioxide.
1
....................................................................................................................................
....................................................................................................................................
(ii)
A mixture of 15.0 L of sulfur dioxide and 12.0 L of oxygen is reacted.
Calculate the volume of gas after the reaction is complete.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
Page 11
1
STUDENT NUMBER/NAME: ……………………..
Question 25 (5 marks)
Marks
The reactivity of various metals and their first ionisation energies are listed in the table below.
Element
Magnesium
Calcium
Zinc
X
(a)
Reactivity with
water
Reacts with steam
at high
temperatures
Reacts with water
at room
temperature
Reacts with steam
at high
temperatures
Reacts violently
with water at room
temperature
Reactivity with
dilute acid
1st ionisation
energy (kJ/mol)
Reacts rapidly;
produces heat
740
Reacts very
rapidly; produces a
lot of heat
600
Reacts moderately
fast
906
425
Define first ionisation energy.
1
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(b)
Predict the group of the periodic table that X most likely belongs to. Justify your answer.
2
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(c)
Construct TWO half-equations to show the electron transfer reaction that occurs between
magnesium and hydrochloric acid.
.............................................................................................................................................
.............................................................................................................................................
Page 12
2
STUDENT NUMBER/NAME: ……………………..
Question 26 (4 marks)
Marks
The flow chart below represents the basic stages in the recycling of aluminium cans.
Steel
(a)
Waste
By referring to this chart outline at least four main steps involved in recycling aluminium.
2
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(b)
Alumina (aluminium oxide) is purified in the Bayer Process. One step involves converting
the alumina into aluminium hydroxide:
Al2O3(s) + 3H2O → 2Al(OH)3(s)
Calculate the theoretical yield of aluminium hydroxide from 742 grams of alumina.
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Page 13
2
STUDENT NUMBER/NAME: ……………………..
Question 27 (5 marks)
Marks
A student performed a first-hand investigation to determine the solubility of a number of ionic
solids using a series of precipitation reactions.
(a)
Outline a procedure that the student could use to determine the solubility of silver
chloride.
2
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(b)
The student recorded her results in the table below:
Soluble solids
Sodium chloride
Potassium nitrate
Silver nitrate
Barium chloride
Copper sulfate
Insoluble solids
Silver chloride
Barium sulfate
Sodium carbonate
Copper carbonate
Lead sulfate
Write a net ionic equation for the reaction in which barium sulfate was formed.
1
.............................................................................................................................................
(c)
The student checked the reliability of her results by comparing them to a table of solubility
rules she found in a text book. A summary of some of these solubility rules is shown in the
table below.
Soluble anions
NO3–
Cl–
Br–
SO42–
(i)
Exceptions (insoluble)
None
Ag+, Pb2+
Ag+, Pb2+
Ba2+, Ag+, Pb2+
Insoluble anions
OH–
CO32–
PO43–
Exceptions (soluble)
Na+, K+, Ba2+
Na+, K+
Na+, K+
Which of the student’s results does not agree with the solubility rules?
1
....................................................................................................................................
(ii)
Identify TWO solutions that could be mixed to test the reliability of this
disagreeing result.
....................................................................................................................................
....................................................................................................................................
Page 14
1
STUDENT NUMBER/NAME: ……………………..
Question 28 (4 marks)
(a)
Marks
Using Lewis diagrams, compare the molecular shapes of water and hydrogen sulfide.
2
.............................................................................................................................................
.............................................................................................................................................
(b)
Account for the observation that the boiling point of water is 160 degrees Celsius
higher than that of hydrogen sulfide.
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Page 15
2
STUDENT NUMBER/NAME: ……………………..
Question 29 (5 marks)
Marks
Calcium chloride (CaCl2) dissolves readily in water, however, carbon tetrachloride (CCl4) is
considered to be insoluble in water.
(a)
10.0 g of calcium chloride (CaCl2) was dissolved in sufficient water to give a final
volume of 250.0 mL.
Calculate the concentration of chloride ions (in mol L–1) in this solution.
2
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(b)
(c)
Draw diagrams to show the interactions between the water molecules and the chloride
ions when calcium chloride is dissolved in water.
1
Explain why carbon tetrachloride is insoluble in water.
2
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Page 16
STUDENT NUMBER/NAME: ……………………..
Question 30 (4 marks)
Marks
(a) The viscosity of three common substances is shown in the table below.
Substance
Ethanol
Water
Mercury
Viscosity (mPa s-1)
1.20
1.01
1.55
(i) Assuming all conditions are the same, which of the three substances shown would
flow at the fastest rate?
1
……………………………………………….
(ii) In general, what effect would an increase in temperature have on the viscosity of
these substances?
1
……………………………………………………………………………………
(b) The diagram below shows water drops dripping from a tap.
Tap
Water droplet
Briefly outline why water droplets form spherical droplets.
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Page 17
2
STUDENT NUMBER/NAME: ……………………..
Question 31 (4 marks)
Marks
You have carried out a first-hand investigation on the effect of light on a silver salt.
(a) Describe the procedure you followed in this investigation and identify the salt used.
2
…..……………………………………………………………………………………………
…..……………………………………………………………………………………………
…..……………………………………………………………………………………………
…..……………………………………………………………………………………………
…..……………………………………………………………………………………………
(b) Identify one safety precaution used in this investigation.
1
…..……………………………………………………………………………………………
…..……………………………………………………………………………………………
(c) Identify one practical application of the reaction observed in this investigation.
1
…..……………………………………………………………………………………………
Question 32 (3 marks)
A student mixed 100 mL of 0.10 mol L-1 sodium chloride solution with 100 mL of
0.10 mol L-1 silver nitrate solution. Calculate the mass of silver chloride precipitate
that was formed.
3
………..……………………………………………………………………………………………
………..……………………………………………………………………………………………
………..……………………………………………………………………………………………
………..……………………………………………………………………………………………
………..……………………………………………………………………………………………
Page 18
STUDENT NUMBER/NAME: ……………………..
Question 33 (3 marks)
Marks
(a) A student mixed 50 mL of a barium chloride solution with 50 ml of a sodium sulfate
solution in a foam cup. The temperature of the solution increased from 19.8 °C to 21.2 °Ck.
Assuming the total mass of this solution was 100 g calculate the heat released during
this reaction.
(Specific heat of water = 4.18 J °C-1 g-1).
2
……...…………………………………………………………………………………………
…..…………………………………………………………………………………….………
…..………………………………………………………………………………………….…
…..………………………………………………………………………………………….…
…..……………………………………………………………………………………….……
(b) Suggest one limitation of the apparatus used by the student for this reaction.
1
……...…………………………………………………………………………………………
…..…………………………………………………………………………………….………
End of paper
Page 19