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RECOGNISINGACHIEVEMENT
OXFORDCAMBRIDGE
AND RSA EXAMINATIONS
AdvancedGCE
2815/01
CHEMISTRY
TrendsandPatterns
Tuesday
28 JUNE2OO5
Morning
t hour
Candidates
answeron the questionpaper.
Additionalmaterials:
Data Sheetfor Chemistry
Scientificcalculator
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INSTRUCTIONS
TO CANDIDATES
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Writeyour namein the spaceabove.
Writelour Centrenumberand Candidatenumberin the boxesabove.
Answerall th€ questions.
Writeyouran$versin the spacesprovidedon the questionpaper.
Readeach questioncarefullyand makesure you knowwhatyou haveto do beicrestartingyour
answer.
INFORMATION
FORCANDIDATES
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.
o
.
.
The numberof marksis givenin brackets[ ] at the end of eachquestionor part question.
Youwill be awardedmarksfor the qualityof writtencommunication
wherethis is indicatedin the
question.
Youmayusea scientificcalculator.
FOR EXAMINER'S
USE
Youmay use the Data Sheetfor Chemistry.
Youare advisedto showall the stepsin any calculations.
Max. Mark
Qu.
1
16
2
17
3
12
TOTAL
45
This question paperconsists of 8 printed pages.
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[Turn over
Fw
Examirpfs
Use
2
Answerall the questions.
1
The questionbelowrelatesto chloridesof someof the elementsin Period3 of the Periodic
Table.
(a) Draw 'dot and cross'diagramsto show the bondingin magnesiumchlorideand
silicon(IV)chloride.Onlydrawthe outershellelectrons.
t3I
(b) Describethe differencein behaviourwhen magnesiumchlorideand silicon(IV)
chlorideare addedseparatelyto coldwater.
Youmayincludein youranswer
.
solution,
the pH of any resulting
.
relevantchemicalequations,
o
observations,
experimental
o
the nameof the processtakingplace.
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2815/01Jun05
3
(c) The meltingpoint of magnesiumchlorideis much higherthan that of silicon(IV)
chloride.
For
Examinefs
Use
Explainthisdifferencein termsof structureand bonding.
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(d) Hot aluminiumreactswith dry chlorineto givea whitecompoundwhichhas a relative
molecularmassof 267.
(i) Deducethe molecular
formulafor the whitecompound.
answer
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(ii) Writean equation
anddrychlorine.
forthereaction
between
aluminium
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(iii) Explain why solid aluminium chloride does not conduct electricity,but when
aluminiumchlorideis added to water,the resultingsolutionwill conduct electricity.
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(e) Phosphorus
reactswith excesschlorineto forma compoundwith an empiricalformula
PCls.The solidcompoundhas positiveand negativeions.
The positiveion hasthe formulaPCt4+.
atom.
Theformulaof the negativeion includesone phosphorus
Suggestthe formulaof the negativeion.
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[Total:16]
281V01 JunOS
[Turnover
For
Examinefs
Use
4
and nitratesof Group2 elementsdecomposewhenheated.
The carbonates
of calciumcarbonate.
by the decomposition
(a) Catciumoxideis manufactured
(i) Writethe equationfor thisdecomposition.
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of calciumcarbonateis much lower
temperature
(ii) Explainwhy the decomposition
thanthatof bariumcarbonate.
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when heatedto makebariumoxide,nitrogendioxideand
(b) Bariumnitratedecomposes
oxygen.
2Ba(NOg)z(s)
+
2BaO(s)+ 4NO2(g)+ O2(g)
Equation2.1
reactioninvolvesboth
(i) Use oxidationstates to explainwhy this decomposition
oxidationand reduction.
13l
(ii) Calculatethe enthalPYchange of reaction, LHt, in kJ mol-l, for the thermal
of bariumnitrateusing the enthalpychanges of formation,AH1,
decomposition
givenin the table.
compound
LHttkJ mol-l
ea(NO.)r(s)
-992
BaO(s)
-5s8
NO2(s)
+33
answer
2815/01 Jun05
... kJmol-1I3l
5
For
Examinefs
Use
(c) A studentinvestigates
the volumeof gasformedwhenbariumnitrateis heated.
Thediagramshowsthe apparatusthe studentuses.
100cmagassyringe
t+
tt tl
heat
(i) A 1.31g sampleof bariumnitrateis completely
decomposed.
Use Equation 2.1 to calculatethe volume,in cffi3, of gas formed at room
temperature
and pressure.
1 molof gas moleculesoccupies24000cm3at roomtemperature
and pressure.
answer
cm3 tgl
(ii) Suggestone problemthat the studentmay encounterwhen carryingout the
investigation.
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281U01 JunOS
[Turnover
temperaturethan calciumnitrate.One of
(d) Bariumnitratehas a higherdecomposition
the reasonsfor this is the differencebetweenthe latticeenthalpyof bariumoxideand
thatof calciumoxide.
(i) Explainwhat is meantby the term latticeenthalpy.
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(ii) Explainwhy the lafticeenthalpyof bariumoxideis much less exothermicthan
thatof calciumoxide.
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[Total:17]
2815/01Jun05
Fu
Exanircfs
Use
7
3
of scientificterms.
for the qualityof useandorganisation
In thisquestion,one markis available
For
Examine/s
Us
propertiesof a
Copperand iron are typicaltransitionelements.One of the characteristic
transitionelementis thatit can formcomplexions.
.
whycopperis a transitionelement.
Explainin termsof electronicconfiguration
o
Give an exampleof a complexion that containscopper.Drawthe three dimensional
shapeof the ionanddescribethe bondingwithinthiscomplexion.
o
Transitionelementsshow typical metallicproperties.Describethree other typical
propertiesof transitionelements.lllustrateeach propertyusingcopperor iron or their
compounds.
281S01 Jun05
[Turnover
For
Examinefs
Use
I
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Qualityof WrittenCommunication
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[Total:12]
PAPER
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inadvertently
2815/01JunO5