Module 2 Chemistry Exam questions and Answers.

MODULE 2 - EXAM QUESTIONS

Whymismcalciummnitratemanmexamplemofmamsalt?m(1mmark)m-
m"ACCURATEmANSWER"mmmThemH+mionminmthemacidmismreplacedmbymampositivemmetalmi
on.

Statemonemimportantmusemformthemcompoundm(NH4)2SO4.m(1mmark)m-
m"ACCURATEmANSWER"mmmFertiliser
Manufacturemofmexplosivesm
Dyesm
Cleaningmagents
Refridgerators
Urea

Definemanmacid.m(1mmark)m-m"ACCURATEmANSWER"mmmAcceptsmH+m/mamproton

Amsmallmamountmofmsolidmmagnesiummoxide,mMgO,mwasmreactedmwithmexcessmdilutemhyd
rochloricmacid.
Writemambalancedmequationmformthismreaction.m(1mmark)m-
m"ACCURATEmANSWER"mmmMgOm(s)m+m2HClm(aq)m-->mMgCl2m(aq)m+mH2Om(l)

Writemequations,mincludingmstatemsymbols,mformthemreactionmofmHClmwithmCaCO3mandmth
emreactionmofmHClmwithmCaO.m(3mmarks)m-
m"ACCURATEmANSWER"mmmCaCO3m(s)m+m2HClm(aq)m-->mCaCl2m(aq)m+mCO2m(g)m+mH2O(l)
CaOm(s)m+m2HClm(aq)m-->mCaCl2m(aq)m+mH2Om(l)

Amstudentmaddedmanmexcessmofmhydrochloricmacidmtomanmoldmsamplemofmmagnesiummoxi
demthatmismcontaminatedmwithmmagnesiummcarbonate.
Explain,mwithmthemaidmofmequations,mwhymthemresultingmsolutionmcontainedmonlymonemdis
solvedmcompoundmofmmagnesium.m(3mmarks)m-
m"ACCURATEmANSWER"mmmMgOm+m2HClm-->mMgCl2m+mH2O
MgCO3m+m2HClm-->mMgCl2m+mH2Om+mCO2
Bothmreactionsmproducemmagnesiummchloride

Amstudentmaddedmanmexcessmofmhydrochloricmacidmtomanmoldmsamplemofmmagnesiummoxi
demthatmismcontaminatedmwithmmagnesiummcarbonate.
Statemtwomobservationsmthatmthemstudentmwouldmmake.m(2mmarks)m-
m"ACCURATEmANSWER"mmmSolidmdissolves
CO2mproducedmasmeffervescence

Oldmsamplesmofmmagnesiummoxidembecomemcontaminatedmwithmmagnesiummcarbonate.
(i)mSuggestmhowmthismcontaminationmtakesmplace.m(1mmark)m-
m"ACCURATEmANSWER"mmmMgOmreactsmwithmCO2

Statemthemformulamofmthemcalciummcompoundmformedmwhen:
(i)mcalciummoxidemreactsmwithmwater,
(ii)mcalciummoxidemreactsmwithmnitricmacidm-m"ACCURATEmANSWER"mmmCa(OH)2
Ca(NO3)2

Whymismammoniamactingmasmambaseminmthismneutralisation?m(1mmark)m-
m"ACCURATEmANSWER"mmmacceptsmH+/amproton

Explainmwhatmismmeantmbymthemtermmsalt.m(1mmark)m-
m"ACCURATEmANSWER"mmmH+mionminmthemacidmismreplacedmbymampositivemmetalmion

, Ammoniummcompoundsmsuchmasmammoniummsulfate,m(NH4)2SO4,mcanmbemusedmasmfertilis
ers.
(i)mWritemambalancedmequationmtomshowmhowmammoniummsulfatemcouldmbemformedmby
mthemreactionmbetweenmaqueousmammoniamandmsulfuricmacid.m(1mmark)m-
m"ACCURATEmANSWER"mmm2NH3m+mH2SO4m-->m(NH4)2SO4

Whatmtermmismgivenmtomthem'•xmH2O'mpartmofmthemformula?m(1mmark)m-
m"ACCURATEmANSWER"mmmWatermofmcrystallisation

Explainmhowmthemhydroxidemionminmaqueousmcalciummhydroxidemactsmasmambasemwhenmi
tmneutralisesmdilutemnitricmacid.m(m1mmark)m-
m"ACCURATEmANSWER"mmmAcceptsmH+/amproton

Writemthemequationmformthemreactionmbetweenmdilutemnitricmacidmandmcalciummhydroxide.
mIncludemstatemsymbols.m(2mmarks)m-
m"ACCURATEmANSWER"mmm2HNO3m(aq)m+mCa(OH)2m(aq)m-->mCa(NO3)2m(aq)m+m2H2O(l)

ExplainmthemdifferentmboilingmpointsmofmNH3,mF2mandmBr2.
NH3m=m-m33
F2m=m-188
Brm=m59
(5mmarks)m-m"ACCURATEmANSWER"mmmBetweenmallmmoleculesmaremintermolecularmforces.
Fluorinemhasminducedmdipolem-
mdipolemforcesmbetweenmfluorinemmoleculesmandmbrominemalsomhasminducedmdipolem-
mdipolemforcesmbetweenmbrominemmolecules.
Thesemforcesmaremweakmsomrequiremlittlemenergymtomovercome.
Brominemhasmamhighermboilingmpointmasmismamlargermmoleculemsomhasmmoremelectrons.m
Thismmeansmthatmitmhasmstrongerminducedmdipolem-mdipolemforces.
NH3mhasmhydrogenmbondingmbetweenmammoniammoleculesmwhichmIsmthemstrongestminter
molecularmforcemtype.mItmrequiresmmoremenergymtomovercomemthanminducedmdipolem-
mdipolemforcesmsomNH3mhasmamhighermboilingmpointmthanmF2mandmBr2

ExplainmwhymH2SmhasmamlowermboilingmpointmthanmH2OmandmH2Sem(4mmarks)m-
m"ACCURATEmANSWER"mmmH2SmandmH2Semhasminducedmdipolem-
mdipoleminteractionsmbetweenmmoleculesmwhichmaremweakmandmsomdon'tmrequiremmuchm
energymtomovercome.mH2Semhasmstrongerminducedmdipolem-
mdipolemforcesmasmismamlargermmoleculemandmsomhasmmoremelectrons
HowevermH2Omcontainsmhydrogenmbondingmwhichmismthemstrongestmintermolecularmforcem
type.
Themhydrogenmbondingmismstrongermthanmtheminducemdipolem-
mdipoleminteractionsminmH2SmandmH2Se.

ExplainmwhymCH2Cl2mismampolarmmoleculem(1mmark)m-
m"ACCURATEmANSWER"mmmChlorinemIsmmoremelectronegativemthanmcarbon.
Themmoleculemismasymmetricalmandmsomthemdipolesmdomnotmcancelmeachmothermout.

Explainmwhatmismmeantmbymelectronegativity.m(2mmarks)m-
m"ACCURATEmANSWER"mmmThemabilitymofmanmatommtomattractmthembondingmelectronsmi
nmamcovalentmbond

Whymismhexan-1-olmlessmsolublemthanmhexane-1,6-diol.m(1mmark)m-
m"ACCURATEmANSWER"mmmTheymbothmformmhydrogenmbondsmwithmwater.
Hexan-1,6-diolmhasmmoremOHmgroupsmandmsomformsmmoremhydrogenmbondsmwithmwater

Statemwhethermthemfollowingmsubstancesmconductmelectricitymwhenmsolidmormmoltenmandm
explainmyourmanswersminmtermsmofmparticlesminvolved.m(5mmarks)
Aluminium