GCE AS/A level - Revision Science · 4 04 (1091-01) Examiner only 4.ample A s of 0.50 g of calcium...
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1091 010001 ADDITIONAL MATERIALS In addition to this examination paper, you will need a: • calculator; • copy of the Periodic Table supplied by WJEC. Refer to it for any relative atomic masses you require. INSTRUCTIONS TO CANDIDATES Use black ink or black ball-point pen. Do not use gel pen or correction fluid. Write your name, centre number and candidate number in the spaces at the top of this page. Section A Answer all questions in the spaces provided. Section B Answer all questions in the spaces provided. Candidates are advised to allocate their time appropriately between Section A (10 marks) and Section B (70 marks). INFORMATION FOR CANDIDATES The number of marks is given in brackets at the end of each question or part-question. The maximum mark for this paper is 80. Your answers must be relevant and must make full use of the information given to be awarded full marks for a question. The QWC label alongside particular part-questions indicates those where the Quality of Written Communication is assessed. If you run out of space, use the additional page(s) at the back of the booklet, taking care to number the question(s) correctly. SM*(S15-1091-01) Surname Other Names Candidate Number 2 Centre Number MAY1510910101 © WJEC CBAC Ltd. GCE AS/A level 1091/01 CHEMISTRY – CH1 A.M. FRIDAY, 22 May 2015 1 hour 30 minutes S15-1091-01 For Examiner’s use only Question Maximum Mark Mark Awarded Section A 1. to 4. 10 Section B 5. 11 6. 12 7. 14 8. 19 9. 14 Total 80
Transcript of GCE AS/A level - Revision Science · 4 04 (1091-01) Examiner only 4.ample A s of 0.50 g of calcium...
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ADDITIONAL MATERIALS
In addition to this examination paper, you will need a:• calculator;• copyofthePeriodic Table supplied by WJEC. Refertoitforanyrelative atomic masses you require.
INSTRUCTIONS TO CANDIDATES
Useblackinkorblackball-pointpen.Donotusegelpenorcorrectionfluid.Writeyourname,centrenumberandcandidatenumberinthespacesatthetopofthispage.Section A Answer allquestionsinthespacesprovided.Section B Answer allquestionsinthespacesprovided.Candidatesareadvised toallocate their timeappropriatelybetweenSection A (10 marks) and Section B (70 marks).
INFORMATION FOR CANDIDATES
Thenumberofmarksisgiveninbracketsattheendofeachquestionorpart-question.Themaximummarkforthispaperis80.Youranswersmustberelevantandmustmakefulluseoftheinformationgiventobeawardedfullmarksforaquestion.The QWC label alongsideparticular part-questions indicates thosewhere theQuality ofWrittenCommunicationisassessed.Ifyourunoutofspace,usetheadditionalpage(s)atthebackofthebooklet,takingcaretonumberthequestion(s)correctly.
SM*(S15-1091-01)
Surname
Other Names
CandidateNumber
2
CentreNumber
MAY1510910101 © WJEC CBAC Ltd.
GCE AS/A level
1091/01
CHEMISTRY – CH1
A.M.FRIDAY,22May2015
1 hour 30 minutes
S15-1091-01
For Examiner’s use only
Question MaximumMark
MarkAwarded
Section A 1. to 4. 10
Section B 5. 11
6. 12
7. 14
8. 19
9. 14
Total 80
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SECTION A
Answer all questions in the spaces provided.
1. Completethetablebelowtoshowthecompositionofthefollowingspecies. [2]
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2. The isotope 226Raisradioactive.Itdecaysbyα-emissionandhasahalf-lifeof1600years.
(a) Givethemassnumberandsymbolofthespeciesformedbythelossofoneα-particlefromanatomof226Ra. [1]
(b) State what is meant by the term half-life. [1]
(c) Asampleof226Ra,ofinitialmass1.00g,decaysfor3200years. Calculatethenumberofmolesof226Raleftafterthisperiod. [2]
Number of moles = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mol
Species Protons Neutrons Electrons
Ne
O2−
20
18
10
8
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only3. Methanoicacidisthesimplestcarboxylicacidandoccursnaturally,mostnotablyinantvenom.
Ithasamolarmassof46.02gmol−1.
(a) State what is meant by molar mass. [1]
(b) Use the values in the table below to calculate the enthalpy change of formation formethanoicacid. [1]
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CO2(g) + H2O(I)
HCOOH(I) + O2(g)C(s) + H2(g) + 1 O2(g)12
12
Substance Enthalpychangeofcombustion,∆Hθ/kJmol−1
C −394
H2 −286
HCOOH −263
c
∆Hθ = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .kJmol−1f
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4. Asampleof 0.50gof calciumcarbonate completely reactswith 50cm3 of hydrochloric acidsolutionofconcentration2.0moldm−3togivecalciumchloride,carbondioxideandwater.
(a) Suggestamethodformeasuringtherateofthisreaction. [1]
(b) State, giving a reason, what effect using 100cm3 of hydrochloric acid solution ofconcentration2.0moldm−3wouldhaveontheinitialrateofthisreaction. [1]
Section A Total [10]
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SECTION B
Answer all questions in the spaces provided.
5. (a) Electronsarearrangedinenergylevels.Thediagrambelowshowstwoelectronsinthe1slevelinanitrogenatom.
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Completethediagramfortheelectronsinanitrogenatombylabellingthesub-shelllevelsandshowinghowtheelectronsarearranged. [2]
(b) Nitrogenformsseveraloxides.
(i) Anoxideofnitrogencontains25.9%bymassofnitrogen.Calculatetheempiricalformulaofthisoxide. [2]
Empirical formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(ii) Dinitrogenoxideisformedwhenammoniaisoxidised.
. . . . . . . . . . . NH3 + . . . . . . . . . . . O2 . . . . . . . . . . . N2O + . . . . . . . . . . . H2O
Balancetheequationabove. [1]
Energy
1s
. . . . . . . . . . . . .
. . . . . . . . . . . . .
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only (iii) Nitrogendioxideisformedwhencalciumnitratedecomposes.
2Ca(NO3)2 (s)2CaO(s)+ 4NO2(g)+O2(g)
Calculate the totalvolumeofgas,measuredat roomtemperatureandpressure,whichwouldbeproducedwhen0.886gofcalciumnitratedecomposes. [3]
[1molofgasoccupies24.0dm3atroomtemperatureandpressure]
Volume = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . dm3
(c) HydratedcalciumnitratecanberepresentedbytheformulaCa(NO3)2.xH2O.
A6.04gsampleofCa(NO3)2.xH2Ocontains1.84gofwaterofcrystallisation.
Calculatethevalueofx inCa(NO3)2.xH2O. You mustshowyourworking. [3]
x = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Total[11]
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6. Ionisationenergiesandatomicspectraprovideevidence for thearrangementofelectrons inatoms.
(a) ThefollowingdiagramshowsthefirstionisationenergiesofthePeriod3elements.
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200
400
600
800
1000
1200
1400
1600
100
0
300
500
700
900
1100
1300
1500
First ionisation energy/kJmol−1
Element
Na Mg Al Si P S Cl Ar
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only (i) Statethemeaningofthetermmolar first ionisation energy. [2]
(ii) Drawacrossonthediagramtosuggestthefirstionisationenergyofaluminium.[1]
(iii) Explainwhy the valueof the first ionisationenergyof sulfur is less than that ofphosphorus. [2]
(b) Thetablebelowgivessomeionisationenergiesformagnesium.
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1st 2nd 3rd 4th 5th
Ionisationenergy/kJmol−1 736 1450 10500 13 629
(i) Explainwhythesecondionisationenergyisgreaterthanthefirst. [1]
(ii) Complete the table by suggesting a value for the third ionisation energy ofmagnesium. [1]
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(c) Explainbriefly how the lines in the visibleatomicemission spectrumof hydrogenareformed and why the lines become closer together at the high frequency end of thespectrum. [4]
QWC[1]
Total[12]
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7. (a) Lithium was discovered in 1817 by the Swedish chemist Johan August Arfwedson. ItsnamederivesfromtheGreekword lithos,meaning‘stone’,toreflectitsdiscoveryina solidmineral, as opposed to potassium,which had been isolated fromplant ashes 10 years earlier. Naturally occurring lithium is composed of two stable isotopes – 6Li and 7Li.
Inamassspectrometer,asampleoflithiummustbeionisedbeforeitcanbeanalysed.
(i) Describe how vaporised atoms of Li are converted into Li+ ions in a mass spectrometer. [2]
(ii) Suggestwhynomore than theminimumenergy isusedto ionise thesampleoflithium. [1]
(iii) State the difference, if any, between the chemical properties of the isotopes 6Li and 7Li,givingareasonforyouranswer. [2]
(b) Themassspectrumofanaturallyoccurringsampleoflithiumgavethefollowingresults.
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Isotope %abundance6Li 7.257Li 92.75
Theseresultscanbeusedtodeterminetherelativeatomicmassofthelithiumsample.
(i) Calculatetherelativeatomicmassofthesample. [2]
Relative atomic mass = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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only (ii) StateandexplainwhichoftheLi+ionsformedfromtheisotopesofLiwillbedeflected
moreinamassspectrometer. [1]
(c) Lithiumhydroxide reactswithammoniumsulfate to formammonia, lithiumsulfateandwater as shown in the equation below.
(NH4)2SO4 + 2LiOH 2NH3 + Li2SO4 + 2H2O
A2.06g sampleofammoniumsulfatereactedexactlywith29.80cm3ofalithiumhydroxidesolution.
(i) Calculate the amount, in moles, of (NH4)2SO4 in 2.06g of ammonium sulfate. Giveyouranswertothreesignificantfigures. [2]
Number of moles = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mol
(ii) Calculatetheconcentration,inmoldm−3,ofthelithiumhydroxidesolutionused.[2]
Concentration = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mol dm−3
(iii) Calculate the percentage atom economy for the production of ammonia in thereactionbetweenammoniumsulfateandlithiumhydroxide. [2]
Atom economy = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . %
Total[14]
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8. (a) Plannershavetoensureasecuresupplyofenergyinthefuture.Ithasbeensuggestedthattheuseoffossilfuelsshouldbereduced,theuseofrenewableenergyincreasedandthatenergyefficiencyshouldbegreatlyimproved.
Byconsideringboththebenefitsandthedifficultiesinvolved,discusswhetheryouthinkthatthesesuggestionsarerealistic. [4]
QWC[1]
(b) NitricacidisproducedbytheOstwaldprocess.
Thefirststageinvolvestheoxidationofammoniaoveraplatinum/rhodiumcatalyst.
ammonia+oxygennitricoxide+water
Thegraphbelowshowshowtheyieldofnitricoxide,NO,dependsonthetemperatureandpressureusedinitsproduction.
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600 °C800°C1 000 °C
YieldofNO
Pressure
14
a
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only (i) I. Statethegeneralvariationsinthisyieldwithtemperatureandpressure. [1]
II. Usethegraphstoexplainwhetherthereactionisendothermicorexothermicandwhethertherearemoremolesofgaseousproductsthanreactants. [4]
QWC [1]
(ii) Normallytheprocessiscarriedoutatatemperatureofaround900°C. Suggestwhythistemperatureisused. [2]
(iii) Statethetypeofcatalystused. [1]
(iv) Explainwhytherehasbeenmuchresearchtofindabettercatalyst. [2]
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(v) Thenext stage in theOstwaldprocess is to convert thenitric oxide tonitrogendioxide.
2NO(g)+O2(g)2NO2(g)∆H=−114kJmol−1
Sketchontheaxesbelowtheenergyprofileforthisreaction,clearlylabellingtheenthalpychangeofreaction,∆H. [2]
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Energy
Extentofreaction
(vi) Writeanexpressionthatconnectstheenthalpychangeofareaction,∆H, with the activationenergiesoftheforward(Ef)andreverse(Eb)reactions. [1]
Total[19]
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9. Zacwasaskedtomeasurethemolarenthalpychangeofneutralisationofsodiumhydroxidebyhydrochloricacid.
NaOH(aq) + HCI(aq)NaCl(aq)+ H2O(I)
Hewastoldtousethefollowingmethod:
• Measure25.0cm3ofsodiumhydroxidesolutionofconcentration0.970moldm−3 into a polystyrenecup.
• Measurethetemperatureofthesolution.
• Placethehydrochloricacidsolutionintoasuitablecontainerandmeasurethetemperatureofthesolution.
• Whenthetemperaturesofbothsolutionsareequaladd5.00cm3ofhydrochloricacidtothe sodium hydroxide and stir.
• Measurethetemperatureofthemixture.
• Keep adding 5.00cm3 portions of hydrochloric acid, until 50.0cm3 have been added,stirringandmeasuringthetemperatureeachtime.
Zac’sresultsareshownonthegraphbelow.
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0
25
27
29
24
26
28
30
31
10 20 30 40 505 15 25 35 45
Temperature/ °C
VolumeHCladded/cm3
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(a) Suggestwhyitisimportantthatthehydrochloricacidandthesodiumhydroxideareatthesametemperature. [1]
(b) Bydrawinglinesofbestfitforbothsetsofpointsdetermine:
(i) themaximumtemperaturechange [2]
Maximum temperature rise from the graph = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °C
(ii) thevolumeofacidrequiredtoneutralisethesodiumhydroxide. [1]
Volume of acid = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cm3
(c) Use your value from part (b)(ii) to calculate the concentration, in mol dm−3, of thehydrochloricacidsolution. [2]
Concentration = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mol dm−3
(d) Use both valuesfrompart(b)tocalculatetheheatgivenoutduringthis experiment.
[Assumethatthedensityofthesolutionis1.00gcm−3andthatitsspecificheatcapacityis4.18JK−1g−1] [1]
Heat given out = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J
(e) Calculatethemolarenthalpychange,∆H,forthereactionbetweensodiumhydroxideandhydrochloricacid. [2]
∆H = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kJmol−1
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(f) NameapieceofapparatusthatZaccouldusetomeasureexactly25.0cm3ofthesodiumhydroxidesolution. [1]
(g) Explain why the temperature falls on continuing to add hydrochloric acid after the maximumtemperaturehasbeenreached. [2]
(h) ThedatabookvalueforthismolarenthalpychangeofneutralisationismoreexothermicthanZac’svalue.
State the mainreasonforthedifferencebetweenthevaluesandsuggestonechangethatwouldimprovehisresult. [2]
Total[14]
Section B Total [70]
END OF PAPER
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Additional page, if required.Write the question number(s) in the left-hand margin.
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22 (1091-01)
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Additional page, if required.Write the question number(s) in the left-hand margin.
23 © WJEC CBAC Ltd.
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© WJEC CBAC Ltd.
GCE AS/A level
1091/01-A
CHEMISTRY – PERIODIC TABLEFOR USE WITH CH1
A.M. FRIDAY, 22 May 2015
SM*(S15-1091-01A)© WJEC CBAC Ltd.
S15-1091-01A
6.94 Li
Lith
ium
3
9.01 Be
Bery
llium
4
10.8 B
Bor
on 5
12.0 C
Car
bon
6
14.0 N
Nitro
gen
7
16.0 O
Oxy
gen
8
19.0 F
Fluo
rine
9
20.2
Ne
Neo
n10
23.0
Na
Sod
ium
11
24.3
Mg
Magn
esium
12
27.0 Al
Alumi
nium
13
28.1 Si
Sili
con
14
31.0 P
Phos
phoru
s15
32.1 S
Sulfu
r16
35.5 Cl
Chlo
rine
17
40.0 Ar
Arg
on18
39.1 K
Potas
sium
19
40.1
Ca
Cal
cium
20
45.0
ScSc
andiu
m21
47.9 Ti
Tita
nium
22
50.9 V
Vana
dium
23
52.0 Cr
Chrom
ium24
54.9
Mn
Mang
anes
e25
55.8
Fe Iron
26
58.9
Co
Cob
alt
27
58.7 Ni
Nic
kel
28
63.5
Cu
Cop
per
29
65.4
Zn Zinc 30
69.7
Ga
Gal
lium
31
72.6
Ge
Germ
anium
32
74.9 As
Ars
enic
33
79.0
SeSe
leniu
m34
79.9 Br
Brom
ine
35
83.8 Kr
Kryp
ton
36
85.5
Rb
Rubid
ium37
87.6 Sr
Stro
ntium
38
88.9 Y
Yttri
um39
91.2 Zr
Zirco
nium
40
92.9
Nb
Niob
ium
41
95.9
Mo
Molyb
denum
42
98.9 Tc
Tech
netiu
m43
101
Ru
Ruthe
nium
44
103
Rh
Rhod
ium45
106
PdPa
lladiu
m46
108
Ag Silv
er47
112
Cd
Cadm
ium48
115 In
Indi
um49
119
Sn Tin
50
122
SbAn
timon
y51
128
TeTe
lluriu
m52
127 I
Iodi
ne53
131
XeXe
non
54
133
Cs
Caes
ium
55
137
BaB
ariu
m56
139
LaLa
nthan
um57
179
Hf
Hafn
ium
72
181
TaTa
ntalu
m73
184
WTu
ngste
n74
186
Re
Rhen
ium75
190
Os
Osm
ium
76
192 Ir
Iridi
um77
195
Pt
Plat
inum
78
197
Au Gol
d79
201
Hg
Mer
cury
80
204 Tl
Thall
ium81
207
Pb Lead 82
209 Bi
Bism
uth
83
(210
)Po
Polon
ium84
(210
)At
Asta
tine
85
(222
)R
nR
adon
86
(223
)Fr
Fran
cium
87
(226
)R
aR
adiu
m88
(227
)Ac
Actin
ium89
THE
PER
IOD
IC T
AB
LE1
2 G
roup
34
56
70
1 2 3 4 5 6 7
‣ ‣‣
1.01 H
Hydr
ogen
1
4.00 He
Heliu
m2
d B
lock
s B
lock
Perio
d
p B
lock
140
Ce
Cer
ium
58
141 Pr
Pras
eody
mium
59
144
Nd
Neod
ymiu
m60
(147
)Pm
Prom
ethi
um61
150
SmSa
mar
ium
62
(153
)Eu
Euro
pium
63
157
Gd
Gado
linium
64
159
TbTe
rbiu
m65
163
Dy
Dysp
rosiu
m66
165
Ho
Holm
ium67
167
ErEr
bium
68
169
TmTh
uliu
m69
173
Yb
Ytter
bium
70
175
LuLu
tetiu
m71
232
ThTh
orium
90
(231
)Pa
Prota
ctiniu
m91
238 U
Ura
nium
92
(237
)N
pNe
ptun
ium93
(242
)Pu
Plut
oniu
m94
(243
)A
mAm
erici
um95
(247
)C
mC
uriu
m96
(245
)B
kBe
rkeli
um97
(251
)C
fCa
liforn
ium98
(254
)Es
Eins
teiniu
m99
(253
)Fm
Ferm
ium
100
(256
)M
dM
ende
levium
101
(254
)N
oNo
beliu
m10
2
(257
)Lr
Lawr
enciu
m10
3
f Blo
ck
‣ La
ntha
noid
e
lem
ents
‣‣ A
ctin
oid
e
lem
ents
Ar
Sym
bol
Name Z
rela
tive
atom
icm
ass
atom
icnu
mbe
r
Key
2
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