TASMANIAN QUALIFICATIONS AUTHORITY
PLACE LABEL HERE
Tasmanian Certificate of Education
CHEMISTRY
Senior Secondary
Subject Code: CHM315109
External Assessment
2012
Part 1
Time: approximately 45 minutes
On the basis of your performance in this examination, the examiners will provide a
result on the following criterion taken from the course statement:
Criterion 5
Demonstrate an understanding of the fundamental principles and
theories of electrochemistry.
Criterion
Mark
5
Pages:
Questions:
©
12
7
Copyright for part(s) of this examination may be held by individuals and/or organisations other than
the Tasmanian Qualifications Authority.
/40
Chemistry – Part 1
CANDIDATE INSTRUCTIONS
Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on
this examination paper.
Answer ALL questions (making sure you answer all parts within each question so that the
criteria can be assessed). Answers must be written in the spaces provided on the examination
paper.
The 2012 Chemistry Information Sheet can be used throughout the examination.
No other written material is allowed into the examination.
A TQA approved calculator can be used throughout the examination.
Each booklet is of equal value (40 marks). This examination is 3 hours in length; it is
recommended that you spend no more than 45 minutes on any one of the FOUR parts to this
examination.
In calculations no credit can be given for incorrect answers unless they are accompanied by
details of the working. Some credit will be given for unsimplified answers. Appropriate units
must be included.
All written responses must be in English.
Page 2
Chemistry – Part 1
Question 1
(a)
Calculate the oxidation state of manganese in each of the following compounds
containing manganese, and arrange the compounds in order of increasing oxidation
state of the manganese.
KMnO 4 , Na 2 MnO 4 , MnCl2 , Mn (CH 3COO)3
(2 marks)
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(b)
Rank the compounds in order of decreasing oxidising ability. Explain your order.
(2 marks)
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Chemistry – Part 1
Question 2
Explain in what ways the reaction between magnesium and chlorine:
Mg(s) + Cl2(g) !!!!!!!MgCl2(s)
is similar to the reaction between magnesium and oxygen:
2Mg(s) + O2(g) !!!!!!!2MgO(s)
How do the definitions of oxidation in terms of electron transfer and oxidation states relate to
both reactions.
(4 marks)
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Chemistry – Part 1
Question 3
Gold metal does not react with oxygen, water or dilute acids. It does react with a mixture of
concentrated hydrochloric and nitric acids.
Au(s) + 3NO3!! (aq) +!4Cl–(aq) + 6H +(aq) !!!!!!!AuCl4!!"! (aq) !+!3NO2(g) + 3H 2O(!)
Write the half equations that represent the oxidation and reduction processes.
•
(4 marks)
oxidation half equation
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reduction half equation
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Hence show how they add to give the overall equation given above.
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Comment on the role of the Cl– ions.
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Chemistry – Part 1
Question 4
Standard electrode potentials for the Cu 2+ and Cr 3+ ions are:
(a)
–
Cu 2+
!!!!(aq) + 2e
Cu(s) :
E˚ = 0.34 V
–
Cr 3+
!!!!(aq) + 3e
Cr(s) :
E˚ = –0.74 V
What do these two equations tell us about the relative reducing ability of the metals and
what is the significance of the different signs of the E˚ values?
(3 marks)
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(b)
Use chemical shorthand to represent the electrochemical cell formed from these two
half cells. Write the balanced overall equation for this cell and calculate the maximum
cell EMF.
(3 marks)
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Question 4 continues opposite.
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Chemistry – Part 1
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Question 4 (continued)
(c)
Which one of the following would you use for storage:
•
•
a copper container for chromium (III) chloride?
a chromium container for copper sulfate?
Explain your choice.
(3 marks)
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Page 7
Chemistry – Part 1
Question 5
The diagram below shows how an impure sample of copper can be electrolytically-refined. The
impurities are zinc, gold and silver metals.
(a)
On the diagram label,
(i)
(ii)
(iii)
(iv)
(b)
the charges on the electrodes
a suitable aqueous electrolyte
the anode and the cathode
the impure sample of copper and the electrode where pure copper is deposited.
(2 marks)
By considering the reactions that are possible at both electrodes, discuss what happens to
each of the four metals during this electrolysis process.
(4 marks)
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Chemistry – Part 1
Question 6
THIS QUESTION HAS BEEN REMOVED FROM PUBLICATION AS IT CONTAINED
FACUTAL ERRORS.
(5 marks)
Page 9
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Chemistry – Part 1
Question 7
(a)
The Sydney Harbour Bridge is always being painted,
because by the time the painters have completed
painting they need to start again.
Explain the chemistry behind why the painting is necessary and how the painting is
effective.
(4 marks)
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(b)
A sign on the bridge over the mouth of the Cam River at Somerset says: ‘cathodic
protection works in progress’. Outline the chemical principles involved in cathodic
protection.
(2 marks)
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(c)
Explain why bridges near the sea need greater protection than those in a warm, dry inland
location.
(2 marks)
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Chemistry – Part 1
BLANK PAGE
Page 11
Chemistry – Part 1
BLANK PAGE
Q
This question paper and any materials associated with this examination (including answer booklets, cover
sheets, rough note paper, or information sheets) remain the property of the Tasmanian Qualifications Authority.
Page 12
TASMANIAN QUALIFICATIONS AUTHORITY
PLACE LABEL HERE
Tasmanian Certificate of Education
CHEMISTRY
Senior Secondary
Subject Code: CHM315109
External Assessment
2012
Part 2
Time: approximately 45 minutes
On the basis of your performance in this examination, the examiners will provide a
result on the following criterion taken from the course statement:
Criterion 6
Demonstrate knowledge and understanding of the principles and
theories of thermochemistry, kinetics and equilibrium.
Criterion
Mark
6
Pages:
Questions:
©
12
7
Copyright for part(s) of this examination may be held by individuals and/or organisations other than
the Tasmanian Qualifications Authority.
/40
Chemistry – Part 2
BLANK PAGE
Page 2
Chemistry – Part 2
CANDIDATE INSTRUCTIONS
Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on this
examination paper.
Answer ALL questions (making sure you answer all parts within each question so that the criteria can
be assessed). Answers must be written in the spaces provided on the examination paper.
The 2012 Chemistry Information Sheet can be used throughout the examination.
No other written material is allowed into the examination.
A TQA approved calculator can be used throughout the examination.
Each booklet is of equal value (40 marks). This examination is 3 hours in length; it is recommended
that you spend no more than 45 minutes on any one of the FOUR parts to this examination.
In calculations no credit can be given for incorrect answers unless they are accompanied by details of
the working. Some credit will be given for unsimplified answers. Appropriate units must be included.
All written responses must be in English.
Page 3
Chemistry – Part 2
Question 8
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The chemical equation for the combustion of propane is:
C3H8(g) !!+!!5O2(g) !!!!!!!3CO2(g) !!+!!4H 2O(g)
(a)
Describe how energy is involved in the reaction and how this relates to the overall heat
of reaction.
(3 marks)
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(b)
Some bond energies for bonds in gaseous molecules are listed below:
Bond type
Bond energy (kJ mol!1 )
Bond type
Bond energy (kJ mol!1 )
C–H
416
O=O
498
C–C
C–O
346
358
O–H
C=O
463
804
Use the bond energies in the table, and your knowledge of chemical structures, to
calculate !H (kJmol !1 ) for the combustion of propane.
(3 marks)
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Question 8 continues opposite.
Page 4
Chemistry – Part 2
Question 8 (continued)
Consider the four graphs below showing changes in energy (kJ mol!1 ) against reaction
coordinate.
1.
2.
3.
4.
Reaction coordinate
(c)
One of these graphs represents the combustion of propane. Identify this graph, giving
reasons for your choice. Label the relevant features of this graph.
(4 marks)
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(d)
Identify the graph that represents a process most likely to proceed spontaneously at
room temperature? Explain your choice.
(2 marks)
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Chemistry – Part 2
Question 9
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Consider the two experiments below:
•
an aqueous solution of silver nitrate added to an aqueous solution of sodium chromate
in test tube 1:
2Ag +!!(aq) + CrO2!!
4!!!!!(aq) !!!"!!!Ag 2 CrO 4(s)
(yellow)
•
crystals of silver nitrate added to crystals of sodium chromate in test tube 2.
Describe what you would expect to observe in the test tubes, comparing the reaction rates at
room temperature. Give reasons for the difference. What you would expect to happen if water
was added to the second test tube?
(4 marks)
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Chemistry – Part 2
Question 10
What effect does an increase of temperature have on the rate of a reaction? Explain your
answer using the collision theory. Include a kinetic energy distribution curve in your answer.
(4 marks)
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Chemistry – Part 2
Question 11
Zinc metal reacts with hydrochloric acid at room temperature, whereas copper metal does not.
The reaction is represented by:
Zn(s) + 2HCl(aq) !!!!!!!ZnCl2(aq) + H 2(g)
Wrapping copper wire around a piece of zinc increases the rate of reaction due to the catalytic
oxidation of the copper.
(a)
On the axes below, draw graphs to illustrate the rate of production of hydrogen gas
with and without copper wire. Label each graph.
(2 marks)
Volume of hydrogen
time
(b)
How does a catalyst increase the rate of a reaction?
(1 mark)
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Chemistry – Part 2
Question 12
Consider the reaction:
CaCO3(s)
CaO(s) + CO2(g)
Equilibrium can be established for this reaction in a closed container at constant temperature.
(a)
Comment on the relationship at equilibrium between the forward and reverse reaction
rates, activation energies and !H values.
(3 marks)
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(b)
Why would industries that produce quicklime (calcium oxide, CaO) not use a closed
container?
(2 marks)
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Chemistry – Part 2
Question 13
A NO2(g) / N 2O 4(g) mixture is in a syringe at room temperature. As the piston is gradually
pushed in, the red-brown colour of NO2 darkens at first and then becomes progressively
lighter. It is always darker than it was originally.
The equation for equilibrium is:
(a)
N 2O 4(g)
2NO2(g)
colourless
red-brown
Explain the experimental results using Le Chatelier’s Principle.
(3 marks)
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(b)
For this reaction !H = 59kJ. Write an expression for the equilibrium constant.
Explain (using Le Chatelier’s Principle) what will happen to the value of the
equilibrium constant when the temperature is increased.
(3 marks)
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Chemistry – Part 2
Question 14
The graph below shows the concentrations, over time as conditions change, of three gases A,
B and C. These gases react according to the equation:
A(g) + B(g)
3C(g) ;
!H!!<!!0
Concentration
C
B
A
t0
t1
t2
t3
t4
t5
Time
(a)
Identify the time intervals between t0 and t3 during which the system is at equilibrium.
(1 mark)
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(b)
What change in the conditions would have been responsible for the changes in the
concentrations:
(2 marks)
(i)
at t1 ?
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(ii)
(c)
at t3 ?
Complete the graph up to time t5, indicating the final state of the system.
Page 11
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Chemistry – Part 2
BLANK PAGE
Q
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sheets, rough note paper, or information sheets) remain the property of the Tasmanian Qualifications Authority.
Page 12
TASMANIAN QUALIFICATIONS AUTHORITY
PLACE LABEL HERE
Tasmanian Certificate of Education
CHEMISTRY
Senior Secondary
Subject Code: CHM315109
External Assessment
2012
Part 3
Time: approximately 45 minutes
On the basis of your performance in this examination, the examiners will provide a
result on the following criterion taken from the course statement:
Criterion 7
Demonstrate knowledge and understanding of the properties and
reactions of organic and inorganic matter.
Criterion
Mark
7
Pages:
Questions:
©
12
7
Copyright for part(s) of this examination may be held by individuals and/or organisations other than
the Tasmanian Qualifications Authority.
/40
Chemistry – Part 3
BLANK PAGE
Page 2
Chemistry – Part 3
CANDIDATE INSTRUCTIONS
Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on this
examination paper.
Answer ALL questions (making sure you answer all parts within each question so that the criteria can
be assessed). Answers must be written in the spaces provided on the examination paper.
The 2012 Chemistry Information Sheet can be used throughout the examination.
No other written material is allowed into the examination.
A TQA approved calculator can be used throughout the examination.
Each booklet is of equal value (40 marks). This examination is 3 hours in length; it is recommended
that you spend no more than 45 minutes on any one of the FOUR parts to this examination.
In calculations no credit can be given for incorrect answers unless they are accompanied by details of
the working. Some credit will be given for unsimplified answers. Appropriate units must be included.
All written responses must be in English.
Page 3
Chemistry – Part 3
Question 15
(a)
An element has an atomic number of 20. Write its name and electronic configuration.
(1 mark)
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(b)
Sketch a graph of the first four successive ionisation energies versus the number of
electrons removed from this element. Explain how this relates to the electronic
structure of the atom.
(4 marks)
Energy
1
2
3
4
Number of electrons removed
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Chemistry – Part 3
Question 16
The noble gases were discovered after Mendeleev drew up his periodic table.
(a)
Argon was discovered in 1894 and its relative atomic mass was determined to be 39.9.
Mendeleev thought it should be 38. Give a reason why he might have thought 39.9
was wrong.
(1 mark)
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(b)
Some scientists suggested that the noble gases be placed in front of group 1 (the alkali
metals) and called group 0. Why is this position inconsistent with the structure of the
periodic table?
(2 marks)
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Chemistry – Part 3
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Question 17
Consider the third period elements.
(a)
Explain why these elements change from metals to non-metals across the period.
Describe the variation in the acid-base character of their oxides across the period.
(3 marks)
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(b)
An element, E, in the third period of the Periodic Table has the following properties:
silvery; shiny solid; good electrical conductor; malleable; ductile;
–3
melting point 650˚C; density 1.75g cm ; burns readily in air with a
bright white light to form both an oxide and a nitride; forms a chloride of
formula ECl2 .
Identify the element and write a balanced equation for the formation of the nitride.
(2 marks)
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Page 6
Chemistry – Part 3
Question 18
(a)
Aspirin has the structure shown below.
(3 marks)
COOH
O–COCH3
•
Identify the functional groups present.
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•
From the following list circle those compounds that may react with aspirin.
calcium carbonate
acidified potassium permanganate
ethanol
(b)
sodium metal
sodium hydroxide
Consider the two compounds: dimethylpropane and 1-chlorodimethylpropane.
Write the structural formula for each and compare the physical properties of the
compounds.
(3 marks)
Structural formulae:
dimethylpropane
1-chlorodimethylpropane
Comparison of physical properties: .................................................................................
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Chemistry – Part 3
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Question 19
A hydrocarbon has the following properties.
•
•
•
(a)
When fully combusted in excess oxygen, equal volumes of carbon dioxide and water
vapour are produced under conditions of constant temperature and pressure.
It reacts immediately with bromine water.
It has a relative molecular mass of 42.
Determine the molecular formula of this hydrocarbon and draw its structural formula.
(3 marks)
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(b)
A steel vessel containing only the hydrocarbon was subjected to high pressure, in the
presence of a suitable catalyst. A strong, flexible, solid was formed. Name the solid
and write an equation showing how it was formed.
(3 marks)
(c)
Name and draw the isomer of the hydrocarbon that does not react immediately with
the bromine water.
(1 mark)
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Page 8
Chemistry – Part 3
Question 20
Sodium propanoate is an antifungal agent in bread.
Various organic compounds can be used to prepare sodium propanoate by reacting them
separately with sodium hydroxide.
Name two compounds containing different functional groups that could be used. Write the
two equations using structural formulae.
(7 marks)
Compound 1:
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Equation:
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Compound 2:
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Equation:
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Chemistry – Part 3
Question 21 - amended
The branched chain bromoalkane A was treated as shown in the following flow diagram.
Compound C could not be oxidised further.
(7 marks)
A
C5H11Br
Heat with aqueous NaOH
B
C5H12O
Heat with acidified KMnO4
C
C5H10O
Explain what Compound C might be.
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Draw structural formula for B.
Write an equation for the reaction A ! B .
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Chemistry – Part 3
BLANK PAGE
Page 11
Chemistry – Part 3
BLANK PAGE
Q
This question paper and any materials associated with this examination (including answer booklets, cover
sheets, rough note paper, or information sheets) remain the property of the Tasmanian Qualifications Authority.
Page 12
TASMANIAN QUALIFICATIONS AUTHORITY
PLACE LABEL HERE
Tasmanian Certificate of Education
CHEMISTRY
Senior Secondary
Subject Code: CHM315109
External Assessment
2012
Part 4
Time: approximately 45 minutes
On the basis of your performance in this examination, the examiners will provide a
result on the following criterion taken from the course statement:
Criterion 8
Apply logical processes to solve quantitative chemical problems.
Criterion
Mark
8
Pages:
Questions:
©
12
9
Copyright for part(s) of this examination may be held by individuals and/or organisations other than
the Tasmanian Qualifications Authority.
/40
Chemistry – Part 4
CANDIDATE INSTRUCTIONS
Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on this
examination paper.
Answer ALL questions (making sure you answer all parts within each question so that the criteria can
be assessed). Answers must be written in the spaces provided on the examination paper.
The 2012 Chemistry Information Sheet can be used throughout the examination.
No other written material is allowed into the examination.
A TQA approved calculator can be used throughout the examination.
Each booklet is of equal value (40 marks). This examination is 3 hours in length; it is recommended
that you spend no more than 45 minutes on any one of the FOUR parts to this examination.
In calculations no credit can be given for incorrect answers unless they are accompanied by details of
the working. Some credit will be given for unsimplified answers. Appropriate units must be included.
All written responses must be in English.
Page 2
Chemistry – Part 4
Question 22
At 100˚C, solid ammonium nitrite decomposes according to the equation:
NH 4 NO2(s)!!!!!!!N 2(g) + 2H 2O(g)
224 kJ was released per mole of ammonium nitrite decomposed.
Calculate the quantity of heat released if 2.52 g of solid ammonium nitrite is decomposed at
100˚C.
(2 marks)
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Question 23
Air that has a volume of 500 mL, a pressure of 99.4 kPa and a temperature of 32˚C is cooled
to –15˚C. Calculate the volume of air at this temperature if the pressure is increased to 205.9
kPa.
(3 marks)
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Chemistry – Part 4
Question 24
A solution of iron (II) sulfate can be oxidised using acidified potassium permanganate. The
ionic equation is:
+
2+
3+
MnO 4!! (aq) +!5Fe 2+
!! (aq) + 8H (aq) !!!!!!!Mn !!!!(aq) !+!5Fe !!!!(aq) + 4H 2 O(l)
(a)
Calculate the mass of solid potassium permanganate required to oxidise 2.40 g of
iron (II) sulfate.
(4 marks)
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A solution of iron (II) sulfate can also be oxidised, this time using acidified potassium
dichromate. The ionic equation is:
+
3+
3+
Cr2O 7!2!!!(aq) +!6Fe 2+
!! (aq) +14H (aq) !!!!!!!2Cr !!!!(aq) !+!6Fe !!!!(aq) + 7H 2 O(l)
(b)
In a titration, 26.7 mL of a 0.0565 mol L!1 solution of potassium dichromate was
required to reach the end point with 25.00 mL of a solution of iron (II) sulfate.
Calculate the concentration of the iron (II) sulfate solution.
(3 marks)
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Chemistry – Part 4
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Question 25
Consider the data for the following reactions.
2NH 3(g)
N 2(g) + 2O2(g)
2H 2O(g)
N 2(g) + 3H 2(g)
!H = 92! kJ
2NO2(g)
!H = 68! kJ
2H 2(g) + O2(g)
!H = 484!kJ
Predict the heat released or absorbed in the reaction below for the oxidation of ammonia.
4NH 3(g) + 7O2(g)
4NO2(g) + 6H 2O(g)
(4 marks)
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Chemistry – Part 4
Question 26
Hydrogen fluoride gas, HF, dissolves in water and reacts with water to form a slightly acidic
solution according to the equation:
HF(aq) + H 2O(l)
F !!!(aq) + H 3O +!!(aq)
When 2.94 L of gaseous HF at 25˚C and 101.3 kPa was dissolved in enough water to
produce 1.00 L of aqueous solution, the pH of this aqueous solution was found to
be 2.10 at 25˚C.
Calculate the amount (in mol) of gaseous HF that was dissolved in the water and the
equilibrium concentrations of H 3O +!!(aq),!F !!!(aq) !and!HF(aq). Hence calculate the K a value
for HF(aq) .
(5 marks)
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Chemistry – Part 4
Question 27
Two chemistry students performed an experiment to determine the molar heat of solution of
hydrated sodium thiosulfate, Na 2S2O3.5H 2O. They dissolved 5.80 g of hydrated sodium
thiosulfate in 50.0 mL of water in a calorimeter. The temperature of the water dropped from
23.8˚C to 18.6˚C.
Calculate the molar heat of solution of hydrated sodium thiosulfate. Give your answer to an
appropriate number of significant figures.
(4 marks)
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Chemistry – Part 4
Question 28
A current of 1.2 A is passed through 100.0 mL of a 0.500 mol L!1 zinc sulfate solution for
exactly five minutes. Calculate the mass of zinc that would be deposited on the cathode and
the concentration of the zinc ions remaining in solution.
(6 marks)
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Chemistry – Part 4
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Question 29
The silver content of a silver alloy can be determined as follows.
Take shavings from the alloy and completely dissolve them in nitric acid to
obtain an aqueous solution of silver nitrate. Add an aqueous solution of sodium
chloride to the silver nitrate solution until all the silver is precipitated as silver
chloride.
In an experiment, a mass of 1.56 g of silver alloy shavings gave a precipitate of 1.57 g.
Determine the percentage, by mass, of silver in the alloy.
(4 marks)
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Chemistry – Part 4
Question 30
In a laboratory experiment, 200 mL of 0.100 mol L!1 aqueous solution of aluminium sulfate,
Al2 (SO 4 )3(aq) , is added to 300 mL of a 0.100 mol L!1 aqueous solution of barium chloride,
BaCl2(aq). A white solid identified as barium sulfate precipitates.
Write the equation for this reaction, determine which reagent is in excess and calculate the
maximum mass of the barium sulfate that can form.
(5 marks)
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Chemistry – Part 4
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Chemistry – Part 4
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Q
This question paper and any materials associated with this examination (including answer booklets, cover
sheets, rough note paper, or information sheets) remain the property of the Tasmanian Qualifications Authority.
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