2015 hsc chemistry
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2015 HIGHER SCHOOL CERTIFICATE EXAMINATION
1020
Chemistry
General Instructions
•Readingtime–5minutes
•Workingtime–3hours
•Writeusingblackpen
•Drawdiagramsusingpencil
•Board-approvedcalculatorsmaybeused
•AdatasheetandaPeriodicTableareprovidedatthebackofthispaper
Total marks – 100
Section I Pages2–28
75 marks
Thissectionhastwoparts,PartAandPartB
PartA–20marks
•AttemptQuestions1–20
•Allowabout35minutesforthispart
PartB–55marks
•AttemptQuestions21–30
•Allowabout1hourand40minutesforthispart
Section II Pages29–39
25 marks
•AttemptONEquestionfromQuestions31–35
•Allowabout45minutesforthissection
–2–
Section I75 marks
Part A – 20 marksAttempt Questions 1–20Allow about 35 minutes for this part
Usethemultiple-choiceanswersheetforQuestions1–20.
1 InwhichlayeroftheatmospheredoesozoneabsorbthemostUVradiation?
(A) Mesosphere
(B) Stratosphere
(C) Thermosphere
(D) Troposphere
2 Whichtypeofglasswareisusedinatitrationtodeliveranaccuratevolumeofasolutiontoaknownvolumeofanothersolution?
(A) (B)
(C) (D)
–3–
3 Whatflamecolourdocopperionsproducewhenheated?
(A) Brickred
(B) Blue-green
(C) Palepurple
(D) Yellow-orange
4 WhathappenstoFe2+inthefollowingreaction?
Sn4+ + Fe2+ Sn3+ + Fe3+
(A) Itundergoesoxidationandgainselectrons.
(B) Itundergoesreductionandgainselectrons.
(C) Itundergoesoxidationandloseselectrons.
(D) Itundergoesreductionandloseselectrons.
5 The oxides CaO, CO2, Na2O and N2O4 are placed in water to form four separatesolutions.
Which row of the table correctly indicates the solutions with pH less than 7 and thesolutionswithpHgreaterthan7?
Solutions
pH less than 7 pH greater than 7
(A) CO2 N2O4 CaO Na2O
(B) CaO N2O4 CO2 Na2O
(C) CaO Na2O CO2 N2O4
(D) CO2 Na2O CaO N2O4
6 WhichofthefollowingisthemostsuitablereplacementforCFCsintermsofreducingtheirenvironmentalimpact?
(A) CH4
(B) CH2F2
(C) CH2ClF
(D) CHCl2CCl2F
–4–
7 Adiagramofasimplecellisshown.
CuAg
Ag+(aq)Ag+(aq) Cu2+(aq)Cu2+(aq)
V
Salt bridge
Whichofthefollowingoccurswhenthecellisinoperation?
(A) Silverionsareformedinsolution.
(B) Thecopperelectrodeloseselectrons.
(C) Electronstravelthroughtheelectrolyte.
(D) Thecopperelectrodeincreasesinmass.
8 Whichofthefollowingstatementsbestexplainsthesolubilityofethanolinoctane?
(A) Ethanolandoctanearebothnon-polar.
(B) Ethanolformshydrogenbondswithoctane.
(C) Ethanolformsdispersionforceswithoctane.
(D) Ethanolformsdipole-dipolebondswithoctane.
9 Whatarethereactantsusedtomakethiscompound?
CH3CH2CH2 C
O
O CH2CH2CH3
(A) Butan-1-olandbutanoicacid
(B) Butan-1-olandpropanoicacid
(C) Propan-1-olandbutanoicacid
(D) Propan-1-olandpropanoicacid
– 5 –
10 Which of the equations correctly describes incomplete combustion?
(A) C2H5OH(l) + 2O2(g) 2CO(g) + 3H O(l2 )
(B) C OH(l) + 7O g g l2H5 2 2( ) 2CO2( ) + 3H2O( )
(C) C2H5OH(l) + 3O2(g) 2CO2(g) + 3H O(l2 )
(D) C OH(l) + 2O g s g l2H5 2( ) C( ) + CO( ) + 3H2O( )
11 Two monomers are shown.
C(C)
H
C
H n
C
H H
O O C
O O
(CH2)2C O
H
C OH
H
C
H H
HO OHC
O
C
O
HO (CH2)2
HO(B)
H
C
H
C
H H
O C
O O
(CH2)2C OH
n
O(D)
H
C
H
C
H H
O C
O O
(CH2)2C
n
(A)
H
C
H
C
H H
C
O O
(CH2)2C
Which of the following shows a condensation polymer that could be formed from the monomers?
(A)
nH
C
H
C
H H
C
O O
(CH2)2C
(B)
H H O O
HO C C O C (CH2) C OH2
H H
(C)
H H O O
C C C O O C (CH2) C O2
H H n
H
C OH
H
C
H H
HO OHC
O
C
O
HO (CH2)2
(D)
n
O
H
C
H
C
H H
O C
O O
(CH2)2C
–6–
12 Atransuranicelementcanbeproducedinanuclearreactoraccordingtothisequation:
23994Pu + 2X 241Pu 241
94 95Am + Y
WhichrowofthetablecorrectlyidentifiesXandY?
X Y
(A) Neutron Electron
(B) Proton Neutron
(C) Neutron Proton
(D) Proton Electron
13 WhichofthefollowingsolutionshasthehighestpH?
(A) 1.0molL−1 aceticacid
(B) 0.10molL−1 aceticacid
(C) 1.0molL−1 hydrochloricacid
(D) 0.10molL−1 hydrochloricacid
14 ThegraphshowsthechangesinpHduringatitration.
0
2
6
10
14
4
8pH
12
Volume (mL)
WhichpHrangeshouldanindicatorhavetobeusedinthistitration?
(A) 3.1–4.4
(B) 5.0–8.0
(C) 6.0–7.6
(D) 8.3–10.0
–7–
15 Partofawatercatchmentisshowninthediagram.
Stream
River
Forest
Ocean
Village
Farmland
1 km
X
AsampleofriverwatertakenfrompointXisanalysed.
Whichrowofthetableshowsthemostlikelyresults?
ResultsofwateranalysisatX
Turbidity (NTU)
BOD(ppm)
pH Total dissolved solids (ppm)
(A) 400 18 6.5 22 000
(B) 22 3 8.5 17
(C) 5 18 6.5 22 000
(D) 400 3 8.5 17
16 Theequationdescribesanequilibriumreactionoccurringinaclosedsystem.
X(g) + Y(g) 4Z(g) DH=+58kJ
UnderwhichsetofconditionswouldthehighestyieldofZ(g)beobtained?
Temperature (°C) Pressure (kPa)
(A) 50 100
(B) 50 200
(C) 300 100
(D) 300 200
–8–
17 Whatvolumeofcarbondioxidewillbeproduced if10.3gofglucose is fermentedat25°Cand100kPa?
(A) 1.30L
(B) 1.42L
(C) 2.57L
(D) 2.83L
UsethisinformationtoanswerQuestions18–19.
A sample of pond water from a contaminated site was analysed to determine theconcentrationofleadionsusingthefollowingprocedure.
• Ameasuringcylinderwasusedtocollecta50mLsamplefromthepond.
• Thesamplewasplacedinacleandrybeaker.
• 25.0mLof0.200molL−1sodiumchloridesolutionwasaddedtothesample.
• Theprecipitateoflead(II)chloridethatformedwasfiltered,driedandweighed.Ithadamassof0.13g.
18 Howcouldthereliabilityoftheanalysisofthepondwaterbeimproved?
(A) Analysemoresamplesfromthesamepond
(B) Use50mLofdistilledwaterasacontrolsample
(C) Analysesamplesfromdifferentpondsonthesite
(D) Removeothercontaminantsfromthesamplebeforetheanalysis
19 Whatwastheconcentrationofleadionsinthesample?
(A) 5.0×10−3molL−1
(B) 5.8×10−3molL−1
(C) 9.3×10−3molL−1
(D) 10.7×10−3molL−1
–9–
20 Thetableshowstheheatofcombustionoffourstraightchainalkanols.
Number of C atoms in straight chain alkanol
Heat of combustion (kJmol–1)
1 726
3 2021
5 3331
7 4638
What is the mass of water that could be heated from 20°C to 45°C by the completecombustionof1.0gofheptan-1-ol?
(A) 0.032kg
(B) 0.044kg
(C) 0.36kg
(D) 0.38kg
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© 2015 Board of Studies, Teaching and Educational Standards NSW
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Centre Number
Student Number
43933103511021 15050
2015 HIGHER SCHOOL CERTIFICATE EXAMINATION
Chemistry
Section I (continued)
Part B – 55 marksAttempt Questions 21–30Allow about 1 hour and 40 minutes for this part
Answer the questions in the spacesprovided. These spaces provideguidance for the expected length ofresponse.
Showallrelevantworkinginquestionsinvolvingcalculations.
Extra writing space is provided onpages27and28.Ifyouusethisspace,clearly indicate which question youareanswering.
Write your Centre Number andStudent Number at the top of thispage.
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2381310356
Question 21 (4marks)
(a) Outlineasuitablemethodtoprepareanaturalindicator.
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(b) Howcouldanaturalindicatorbetested?
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Question 22 (7marks)
Thetableshowsdataforozoneconcentrationsover50yearsintheupperatmosphereaboveAntarctica.
Year Ozone Concentration (DobsonUnits)
1955196019701980199520002005
320300300260130130150
(a) Drawalinegraphofthedataonthegridprovided. 4
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4873310354
Question22(continued)
(b) Describeamethodbywhichthisdatacouldhavebeenmeasured.
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7471310351
Question 23 (4 marks)
Explain how the structure and chemistry of ONE of the following cells determines its cost and practicality.
• button cell
• fuel cell
• vanadium redox cell
• lithium cell
• liquid junction photovoltaic device (eg the Gratzel cell)
4
Name of cell: ...........................................................................................................
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9964310350
Question 24 (5marks)
(a) Explainwhythesalt,sodiumacetate,formsabasicsolutionwhendissolvedinwater.Includeanequationinyouranswer.
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(b) Asolutionispreparedbyusingequalvolumesandconcentrationsofaceticacidandsodiumacetate.
ExplainhowthepHofthissolutionwouldbeaffectedbytheadditionofasmallamountofsodiumhydroxidesolution.Includeanequationinyouranswer.
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5638310354
Question 25 (7 marks)
(a) Describe the steps involved in the process of addition polymerisation.
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(b) Explain the uses of polyethylene and polystyrene in terms of their structures and properties.
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9657310359
Question 26 (7marks)
A sodium hydroxide solution was titrated against citric acid (C6H8O7) which istriprotic.
(a) Drawthestructuralformulaofcitricacid(2−hydroxypropane−1,2,3−tricarboxylicacid).
1
(b) How could a computer-based technology be used to identify the equivalencepointofthistitration?
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6157310351
Question 26 (continued)
(c) The sodium hydroxide solution was titrated against 25.0 mL samples of 0.100 mol L−1 citric acid. The average volume of sodium hydroxide used was 41.50 mL.
Calculate the concentration of the sodium hydroxide solution.
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1086310357
Question 27 (5marks)
Namearadioisotopeusedinanon-medicalindustryanddiscussitsuseinthatindustryintermsofitsproperties.
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6784310357
Question 28 (3 marks)
The equipment shown is set up. After some time a ring of white powder is seen to form on the inside of the glass tube.
Cotton woolsoaked in
concentratedhydrochloric
acid
Cotton woolsoaked in
concentratedammonia
Glass tube
Ring ofwhite
powder
(a) Why would this NOT be an acid–base reaction according to Arrhenius?
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(b) Explain why this would be considered a Brönsted–Lowry acid–base reaction. Include an equation in your answer.
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7927310357
Question 29 (7marks)
The procedure of a first-hand investigation conducted in a school laboratory todeterminethepercentageofsulfateinalawnfertiliserisshown.
• 2.00gofasampleoffertiliserwasgroundupandplacedinabeaker.
• Itwasdissolvedinabout200mLof0.1molL−1hydrochloricacid,stirredandfiltered.
• Excessbariumchloridesolutionwasquicklyaddedtothisbeakerandaprecipitateformed.
• Theprecipitatewasthenallowedtosettle,filteredusingfilterpaperandtheresiduecollected.
• Theresiduewasdriedandweighedandhadamassof2.23g.
(a) Suggest modifications that could be made to the procedure to improve theresultsofthisinvestigation.Justifyyoursuggestions.
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9403310358
Question 29 (continued)
(b) Calculate the percentage of sulfate in the original fertiliser sample.
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8246310352
Question 30 (6marks)
The graph shows the percentage yield of ammonia produced from nitrogen andhydrogenatdifferenttemperaturesandpressures.
6
Temperature (°C)
Perc
enta
ge y
ield
of
amm
onia
200 300 400 500 600
90
60
30
0
Pressure
500 atm
400 atm
300 atm
200 atm
TheHaberprocessis themainindustrialprocedurefor theproductionofammonia.ExplaintheconditionsusedintheHaberprocesswithreferencetothegraph.
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9248310355
Section I Part B extra writing space
If you use this space, clearly indicate which question you are answering.
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8455310354OfficeUseOnly–DoNOTwriteanything,ormakeanymarksbelowthisline.
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Section I Part B extra writing space
If you use this space, clearly indicate which question you are answering.
©2015BoardofStudies,TeachingandEducationalStandardsNSW
–29–1022
2015 HIGHER SCHOOL CERTIFICATE EXAMINATION
Chemistry
Section II
25 marksAttempt ONE question from Questions 31–35Allow about 45 minutes for this section
Answerparts(a)–(d)ofonequestionintheSectionIIWritingBooklet.Extrawritingbookletsareavailable.
Showallrelevantworkinginquestionsinvolvingcalculations.
Pages
Question31 IndustrialChemistry...............................................................30–31
Question32 Shipwrecks,CorrosionandConservation..............................32–33
Question33 TheBiochemistryofMovement............................................34–35
Question34 TheChemistryofArt.............................................................36–37
Question35 ForensicChemistry................................................................38–39
–30–
Question 31 — Industrial Chemistry (25marks)
Answer parts (a) and (b) of the question on pages 2–4 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(a) At temperatures above 100°C, hydrogen and carbon monoxide react to formmethanolgasinthisreversiblereaction.
2H2(g)+CO(g)CH3OH(g)
Amixtureofhydrogen,carbonmonoxideandmethanolisplacedinacontainerwithavolumethatcanbechanged.Themixtureisallowedtoreachequilibrium.
(i) Theinitialvolumeofthecontaineris1.00L.
Accountforanychangesintheconcentrationofhydrogengaswhenthevolumeofthecontainerisrapidlyincreasedto2.00L.
2
(ii) The initialmixtureplaced in thecontainerhad0.50molofhydrogen,1.00 mol of carbon monoxide and 2.50 mol of methanol. Once thevolumeof thecontainerhadbeen increased to2.00Landequilibriumhadbeenre-established,thenumberofmolesofhydrogeninthemixturehadchangedby0.36mol.
Calculatetheequilibriumconstantforthisreaction.
3
(b) (i) Describe how saponification can be safely carried out as part of afirst-handinvestigation.
3
(ii) Explainthechemistryrelatedtothecleaningpropertiesoftheproductofsaponification.
4
Question 31 continues on page 31
–31–
Question31(continued)
Answer parts (c) and (d) of the question on pages 5–8 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(c) ThediagramshowspartoftheSolvayprocessforproducingsodiumcarbonate.
Purifiedbrine
Carbondioxide
Ammonia
Reactionvessel
Cooled Filtered Heated Sodiumcarbonate
Calciumchloride
(i) Outline the chemistry of the production of sodium carbonate in theprocessshown.Includeequationsinyouranswer.
3
(ii) Bymakingspecificreferencetothediagram,justifytherequirementsforthelocationofaSolvayprocessplant.
3
(d) Compare the membrane cell method with ONE other method used inthe industrial production of sodium hydroxide in terms of technical andenvironmentalissues.
7
End of Question 31
–32–
Question 32 — Shipwrecks, Corrosion and Conservation (25marks)
Answer parts (a) and (b) of the question on pages 2–4 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(a) (i) Outlinethelimitationsofusingpainttoprotectshipsthatareinconstantuse.
2
(ii) Explainthechemicalprinciplesinvolvedintheuseofasacrificialanode.Includerelevantchemicalequationsinyouranswer.
3
(b) (i) Describeavalidandreliablefirst-handinvestigationthatcanbeusedtocomparetheratesofcorrosionofironwithONEnamedformofsteel.
3
(ii) Explain how the percentage composition of steel can determine itsproperties,withreferencetoTWOtypesofsteel.
4
Question 32 continues on page 33
–33–
Question32(continued)
Answer parts (c) and (d) of the question on pages 5–8 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(c) (i) Theequipmentinthephotographwasusedinanattempttoplateametalspoonwithmagnesiumusinganelectrolyticcellcontainingasolutionofmagnesiumsulfate.
3
Mg(s)
Drawa labelled scientificdiagramof the electrolytic cell. Include thecathode,anode,directionofelectronflowandpolarityoftheelectrodes.
(ii) Explain how Davy’s work increased our understanding of electrontransferreactions.
3
(d) Twoidenticalshipsaresunkinseawater.Oneissunkinshallowwater(60m)andtheotherindeepwater(4000m).Explainhowtherustingprocessesdifferinthesetwoships.Includeequationsinyouranswer.
7
End of Question 32
–34–
Question 33 — The Biochemistry of Movement (25marks)
Answer parts (a) and (b) of the question on pages 2–4 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(a) (i) Asimplifieddiagramofamusclecellisshown. 2
IdentifytheTWOcomponentsofthecellthatareinvolvedinrespirationANDthetypeofrespirationthatoccursineach.
(ii) Explain the biological significance of adenosine triphosphate (ATP)withreferencetoitsstructure.
3
(b) (i) Describe a reliable and valid procedure that can be carried out todemonstratetheeffectofchangingtemperatureonenzymefunction.
3
(ii) Discuss the use of models in understanding how enzymes function inlivingsystems.
4
Question 33 continues on page 35
–35–
Question33(continued)
Answer parts (c) and (d) of the question on pages 5–8 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(c) Asectionofaproteinisshown.
CH
CH3
CH2CH3CH
CH3
CH3
NH3+
NH3+
COO–
CH2CH2
CH2CH2
C
O
S S
O
O
H
CN
H
(i) UsingTWOexamplesfromthediagram,explainhowbondingbetweensectionsoftheproteinchaininfluencesitsshape.
3
(ii) With reference to thediagram,account forways inwhich thisproteinmaybedenatured.
3
(d) Compare the metabolic pathways involved in sprinting with those involvedwhenwalkingatagentlepace.
7
End of Question 33
–36–
Question 34 — The Chemistry of Art (25marks)
Answer parts (a) and (b) of the question on pages 2–4 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(a) (i) Identify the chemical composition of a cosmetic used in an ancientcultureandidentifythepotentialhealthriskassociatedwiththeuseofthecosmetic.
2
(ii) ExplainwhyCr2+(aq)iscolouredwhereasZn2+(aq)isnotcoloured. 3
(b) Aninvestigationistobeconductedtoobservetheflamecolourofsomemetalions.
(i) Describea safeandvalidprocedure thatcanbeused tocarryout thisinvestigation,identifyingthespecificmetalionsobserved.
3
(ii) Explain why only certain metal ions can be identified using flamecolours, naming ONE metal ion that cannot be identified using flamecolours.
4
Question 34 continues on page 37
–37–
Question34(continued)
Answer parts (c) and (d) of the question on pages 5–8 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(c) (i) ThefirstionisationenergyofeachoftheelementsinthethirdrowofthePeriodicTableisgiven.
3
Element Na Mg Al Si P S Cl Ar
Firstionisationenergy(kJmol–1)
494 736 577 786 1060 1000 1260 1520
Use thedata in the table to explainhow the first ionisationenergyoftheseelementscanprovideevidence for theexistenceof sub-shells inatoms.
(ii) ThegraphshowstheelectronegativityvaluesforelementsinPeriods1,2and3ofthePeriodicTable.
0
1.0
2.0
3.0
4.0
2 4 6 8 10
Atomic Number
Ele
ctro
nega
tivity
(P
aulin
g sc
ale)
12 14 16 18 20
Use the graph to explain the relationship between the arrangement ofelectronsinanelementanditselectronegativity.
3
(d) AssesshowtheBohrmodeloftheatomhascontributedtoourunderstandingofatomicstructure,makingreferencetoemissionspectra.
7
End of Question 34
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Question 35 — Forensic Chemistry (25marks)
Answer parts (a) and (b) of the question on pages 2–4 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(a) (i) Comparethecompositionofglycogenwiththatofcellulose. 2
(ii) Relatethedifferencesincompositionofglycogenandcellulosetotheirdifferentstructures.
3
(b) (i) Identify the structure of amino acids and describe the relationshipbetweenaminoacidsandproteins.
3
(ii) Describeasafeandvalidprocedurethatcanbeusedtoshowthepresenceofproteinineggwhite.Includeexpectedresults.
4
Question 35 continues on page 39
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Question35(continued)
Answer parts (c) and (d) of the question on pages 5–8 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.
(c) (i) GeorgeandLindahaveonechild together.Eachof themalsohasonechildfromapreviousrelationship.Aschematicrepresentationof theirDNAprofilesisshownbelow.
3
George Linda Child A
Child B
Child C
DNA profiles obtained from George, Linda and the three children
UsetheinformationintheDNAprofilestoidentifytherelationshipsofChildA,ChildBandChildCtoGeorgeandLinda.Justifyyouranswer.
(ii) DescribethebenefitsofmaintainingDNAdatabanks. 3
(d) Name ONE chromatography technique and assess its use in the analysis offorensicevidence.
7
End of paper
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© 2015 Board of Studies, Teaching and Educational Standards NSW
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1023
2015 HIGHER SCHOOL CERTIFICATE EXAMINATION
Chemistry
DATA SHEET
Avogadroconstant,NA................................................................... 6.022×1023mol–1
Volumeof1moleidealgas:at100kPaandat0°C(273.15K)....................... 22.71Lat25°C(298.15K)..................... 24.79L
Ionisationconstantforwaterat25°C(298.15K),Kw.................. 1.0×10–14
Specificheatcapacityofwater...................................................... 4.18×103Jkg–1K–1
Some useful formulae
pH=– log10[H+] DH=–mCDT
Some standard potentials
AylwardandFindlay,SI Chemical Data(5thEdition)istheprincipalsourceofdataforthisexaminationpaper.Somedatamayhavebeenmodifiedforexaminationpurposes.
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