C1.1TheEarlyatmosphere
Thefirstgasescamefromtheerup1onofVolcanoesandformedtheEarth’searly
atmosphere.
Themaingasesintheearlyatmospherewere:
•  Lotsofcarbondioxide
•  Somenitrogen
•  Li>leornooxygen
•  Watervapour
•  Ammonia
Volcanoesreleasethesegasestoday(andsoscien1ststhinkthesameprocesses
operatedinthepast).
Theoceanswereformedfromthe
condensa1onofthewatervapourto
makeliquidwater.
C1.2achangingatmosphere.
Carbondioxidelevelsfell
Oxygenlevelsrose
Carbondioxidefellbecause:
•  Somecarbondioxide
dissolvedintotheoceans.
•  Somewasabsorbedby
marinecreatureswhostored
it1ntheirshellsascalcium
carbonatewhichlaterformed
carbonaterocks.
Asthenumberofplants
increased,theoxygenlevelsrose
throughphotosynthesis.These
plantsabsorbcarbondioxide
too.
Asimplecarboncycle
Thelevelofcarbondioxideintheatmosphereis
maintainedbyseveralprocesses,photosynthesis,
respira1onandcombus1on
Greenplantsremovecarbondioxidefromthe
atmospherebyphotosynthesis.Respira1onand
combus1onbothreleasecarbondioxideintothe
atmosphere.
Theseprocessesformacarboncycleinwhichthe
propor1onofcarbondioxideintheatmosphere
remainsaboutthesame.
C1.4Theatmosphere
today.
Ouratmospheretoday…
Gas
Formula
%indryair
Nitrogen
N2
78
Oxygen
O2
21
Argon
Ar
0.9
Carbon
Dioxide
other
CO2
0.04
trace
Howdoscien9stsuserockstoworkoutthecomposi9onofthe
Earth’searlyatmosphere?
Analysethemineralsinthemandlookforoxides.Asmoreoxygenwas
present,moreoxidemineralswereformed.
Changesintheatmosphereoccur
through;
Naturalac9vi9es:
•  Volcanicac1vitycanleadtoarisein
sulphurdioxide;lighteningcanlead
toariseinnitrogenoxides.
Humanac9vity:
•  burningfossilfuelscanleadtoan
increaseofcarbondioxide,carbon
monoxideandsulphurdioxide.
•  Deforesta9onleadtoanincreasein
carbondioxide;burningtrees
releasescarbondioxide
(combus1on),fewertreesto
photosynthesiseandabsorbcarbon
dioxide;enginesandfurnaces
releasenitrogenoxides.
•  Farming:increasingnumbersof
ca>leandricefieldscanleadtoan
increaseofmethane.
C1.5RocksandtheirForma1on
IgneousRocks
•  Example–granite.
•  Formedbythesolidifica1onof
magmaorlava
•  Theycontaincrystalswhose
sizedependsontherateof
cooling.
•  Quickcooling=smallcrystals
•  Fastcooling=largecrystals
MetamorphicRocks
•  Example–marble
•  Formedwhenheator
pressureisappliedtoother
rocks.
•  Marbleisformedfrom
chalkorlimestonebeing
heatedandpressurised.
l metamorphic–Arockchangedbypressureandheat.
l sedimentary–Arockformedbythedeposi1onofsediments.
l thermaldecomposi1on–Thebreakdownofacompoundinto
simplersubstancesbyhea1ng.
l electrolysis–Theuseofelectricitytosplitacompound.
l granite–Atypeofigneousrockthatisharderthanlimestoneand
marble.
l igneous–Arockformedfromcooledmagna.
l limestone–Atypeofsedimentaryrockcontainingcalcium
carbonate.
l limewater–Alimestoneproductmadebyfullydissolving
quicklimeinwater.Itisusedtotestforcarbondioxide.
l marble–Atypeofmetamorphicrockthatisharderthanlimestone
butso^erthangranite
Limestone,chalkandmarbleareallformsof
calciumcarbonateandexistintheEarths
crust.
Sedimentaryrocks
•  Sedimentaryrockscontainfossils
•  Theyareformedfromcompac1onof
layersofrockoveralong1me.
•  Theyarenotasstrongasotherrocksso
erodeeasily.
•  Examples-chalkandlimestone
Theadvantagesanddisadvantagesofquarrying.
C1.6Limestone
Limestoneismadeofcalciumcarbonate(CaCO3)
Itisusedin:
–  Buildingmaterials-glass,cement,concrete
–  ImprovingthepHofacidsoil
ThermalDecomposi1onofCalciumCarbonate
Whenmetalcarbonatesareheatedtheybreakdown
intoametaloxideandcarbondioxideisgivenoff
Coppercarbonateàcopperoxide+carbondioxide
CaCO3CaO+CO2
Problemsassociatedwithquarrying:
Economic-money
Social–thepeople
Environmental-pollu1on
Limestoneisheatedwithclaytomakecement
Cementisaddedtosandandwatertomakemortar
Cementisaddedtosand,aggregateandwatertomake
concrete
Advantageofquarrying…jobsandvaluablebuilding
resources.
C1.7Thermaldecomposi1on
Breakingdownwithheat
Easeofthermaldecomposi1onofmetalcarbonates:
•  Mostdifficulttodecomposeissodiumcarbonate(10000C),calciumcarbonate(8250C),zinc
carbonate(3000C)andcoppercarbonate(2000C).
Coppercarbonateàcopperoxide+carbondioxide
CaCO3(s)àCaO(s)+CO2(g)
• 
Coppercarbonatewillstarttodecomposetoformcarbondioxideandcopperoxide.The
reac1onwillabsorbsomeoftheheatfromthefire.Thecarbondioxidecanhelptoputout
thefirebyreducingtheamountofoxygenavailableforcombus1on.
Coppercarbonateàcopperoxide+carbondioxide
Zinccarbonateàzincoxide+carbondioxide
• 
• 
• 
Themassofreactantsdonotchange,thepar1clesjustgetrearranged.
Theatomstakepartinachemicalreac1ontheyareverysmall.
WhencalciumhydroxideisdissolvedinwateritmakesLimewater.
C1.8Chemical
reac1ons
Wordequa9ons
Awordequa1ongivesthenamesofthesubstances
involvedinareac1on.Forexample:
copper+oxygen→copper(II)oxide
Copperandoxygenarethereactants,andcopper(II)
oxideistheproduct.
Precipita9onreac9ons
1)Asimpleexampleofconserva1onofmassisa
precipita9onreac1on.
2)Transi1onmetalsformcolouredcompoundswithother
elements.Manyofthesearesolubleinwater,forming
colouredsolu1ons.Ifsodiumhydroxidesolu1onisthen
added,atransi1onmetalhydroxideisformed.Theseare
insoluble.Theydonotdissolvebutinsteadformsolid
precipitates.Asallthereactantsandproductsremainin
thesealedreac1oncontainerthenitiseasytoshowthat
thetotalmassisunchanged.
coppersulfate+sodiumhydroxide→copper
hydroxide+sodiumsulfate
CuSO4+2NaOH→Cu(OH)2+Na2SO4
C1.9Reac1onsof
Calcium
Compounds
Keywords
•  Neutralisa9onreac9on-reac1oninwhichabaseoranalkalireactswith
anacid.
•  Limewater–Solu1onofcalciumhydroxide.Itisusedtotestforthe
presenceofCO2asitturnsfromcolourlesstocloudy.
MakingLimewater
1.  Hea9nglimestone-Calciumcarbonate(CaCO3)turnsitintoCalciumoxide(CaO)
CaCO3(s)
CaO(s) +CO2(g)
2.  AddingwatertoCaO–vigorousreac1onthatcreatescalciumhydroxide(crumblysolid)
CaO(s)+H2O(l)
Ca(OH)2(s)
Tes9ngforCO2-limewaterturnscloudy/milkyascalciumcarbonateforms.
Ca(OH)2(s)+CO2(g)CaCO3(s)+H2O(l)
NB–largequan99esofCO2willdissolvetoformanacid.ThisreactswiththeCaCO3makingit
colourlessagain!
Neutralisingacidswithlimestone
1.  Calciumcompoundsthatneutraliseacids:
–  Calciumcarbonate(CaCO3)
–  Calciumoxide(CaO)
–  Calciumhydroxide(Ca(OH)2)
2.  Usesofthesealkalis
1.  Farmersneutralisesoil
2.  Powersta9onsusewetpowderedCaCO3toneutraliseacidicwastegaseslikeSulfurdioxideand
nitrousoxides.(belowistheequa9onforsulfurdioxideproduc9on)
S(g)+O(g)
SO2(g)
1.10indiges1on
• 
• 
• 
Hydrochloricacidisproducedinthe
stomachtokillbacteriaandtohelp
diges1on.
Indiges9onremediescontainsubstancestoneutraliseexcessstomachacid.
Whenanacidiccompounddissolvesinwateritproduceshydrogenions,H+.Theseionsare
responsiblefortheacidityofthesolu1on.
Whenanalkalinecompounddissolvesinwateritproduceshydroxideions,OH−.Theseionsare
responsibleforthealkalinityofthesolu1on.
Acidsreactwithalkalistoformsalts.Thesearecalledneutralisa9onreac9ons.Ineachreac1on,
waterisalsoformed:
Acid+alkali→salt+water
Example
Hydrochloricacid+sodiumhydroxide→sodiumchloride+water
HCl+NaOH→NaCl+H2O
• 
Hydrochloricacidcontainshydrogenionsandchlorideionsdissolvedinwater.
• 
Sodiumhydroxidesolu1oncontainssodiumionsandhydroxideionsdissolvedinwater.
Hydrochloricacidproduceschloridesaltse.g.calciumchloride
Nitricacidproducesnitratesaltse.g.calciumnitrate
Sulfuricacidproducessulfatesaltse.g.calciumsulfate
• 
C1.11Neutralisa9on
Youneedtobeabletodescribethereac1onsofhydrochloricacidandsulfuricacidwith
metalhydroxides,metaloxidesandmetalcarbonates.
Metalhydroxides
•  Metalhydroxides,suchassodiumhydroxide,usuallydissolveinwatertoformclear,
colourlesssolu1ons.Whenanacidreactswithametalhydroxide,theonlyproductsformed
areasaltpluswater.Hereisthegeneralwordequa1onforthereac1on:
acid+metalhydroxide→asalt+water
•  thereisatemperaturerise
•  thepHofthereac1onmixturechanges
Metaloxides
•  Somemetaloxides,suchassodiumoxide,dissolveinwatertoformclear,colourless
solu1ons.Manyofthemarenotsolubleinwater,buttheywillreactwithacids.Copper(II)
oxideislikethis.Whenanacidreactswithametaloxide,theonlyproductsformedareasalt
pluswater.Hereisthegeneralwordequa1onforthereac1on:
acid+metaloxide→asalt+water
Metalcarbonates
•  Althoughsodiumcarbonatecandissolveinwater,mostmetalcarbonatesarenotsoluble.
Calciumcarbonate(chalk,limestoneandmarble)islikethis.Whenanacidreactswitha
metalcarbonate,theproductsformedareasaltpluswater,butcarbondioxideisalso
formed.Hereisthegeneralwordequa1onforthereac1on:
acid+metalcarbonate→asalt+water+carbondioxide
•  Youusuallyobservebubblesofgasbeinggivenoffduringthereac1on.Youcanshowthatthe
gasiscarbondioxidebybubblingitthrough
c1.13electrolysis
Electrolysis
Theprocessinwhichelectricalenergyfromad.c.supplydecomposescompounds
Theprocessofelectrolysis
•  Posi1velychargedionsmovetothe
nega1veelectrodeduring
electrolysis.Theyreceiveelectrons
andarereduced.
•  Nega1velychargedionsmovetothe
posi1veelectrodeduringelectrolysis.
Theyloseelectronsandareoxidised.
ELECTROLYSISOFHydrochloricAcid
•  Produceschlorineattheposi1ve
electrode
•  Produceshydrogenatthenega1ve
electrode
C1.14theimportanceofchlorine/Productsfrom
sodiumchloride
Learnallofthis
1.15ElectrolysisofWater
Water
•  Producesoxygenattheposi1ve
electrode
•  Produceshydrogenatthe
nega1veelectrode
•  Ifthegasrelightsaglowing
splint,itisoxygen.
ElectrolysisofSeawater
•  Thisproduceschlorinegasat
theelectrode.
1.16ores
Goldandpla1numfoundnaturallyinthe
environmentastheyareunreac1ve.
Mostmetalsarefoundasores(usually
reactedwithoxygen)intheEarthscrust.
Oresarerockswhichcontainmetals.
Extrac9on=geqngthemetaloutofthe
rock.Some1mesyoucan…
•  Heattherocktogetthemetal
•  Oruseelectrolysis.
Usesofmetals.
Gold=jewellery
Copper=wires
Silver=jewellery
C1.26Acidrain
Effectsofacidrain
-  Fishnumbersstartedtodecrease.
-  Soilsaremadeacidandcanharmplants.
-  Treesdamaged
-  Erosionofbuildingsmadeoflimestone.
Causesofacidrain.
-  Dissolvedcarbondioxideandacidicgasesin
water.
-  Sulphurdissolvedinwaterfromfossilfuels.
-  Burningoffossilfuelswhichcreatesulphur.
C1.17Extrac1ng
metal
l  anode–Theposi1veelectrodeusedinelectrolysis.
l  cathode–Thenega1veelectrodeusedinelectrolysis.
l  electrolysis–Theuseofanelectriccurrenttoseparate
outtheelementsinacompound.
l  electrolyte–Anioniccompoundthatconducts
electricitywheninaliquidstate.
l  ore–Arockthatcontainsametalcombinedwithother
elementsinconcentra1onsthatmakeitprofitabletomine.
Ironisheatedwithcarboninareduc1on
reac1ontoextractitfromitsore.
Ironoxide+carbonàiron+carbon
dioxide
Aluminiumisextractedfromitsoreby
electrolysisbecauseitismorereac1ve.
Aluminiumoxideàaluminium+oxygen
Factorswhichaffecthowametalisextractedare
costandposi1oninthereac1vityseries
C1.18Oxida1onandreduc1on
Keywords
Reduc9on–occurswhenoxygenisremovedfromacompound
Corrosion–whenametalisconvertedtoitsoxidebytheac1onofmoistair
Oxida9on–occurswhenoxygenisaddedtoanelementorcompound
Rus9ng–thecorrosionofiron
Metalextrac9onisreduc9on
•  Mostmetaloresare‘oxides’
•  Togetthemetalwemustremovetheoxygen
• 
• 
• 
Wesaythecompoundhasbeenreduced.ItisaREDUCTIONreac1on
Example1=IronoxideisheatedwithCarbon
Ironoxide+Carbon
Iron+Carbondioxide
Example2=Aluminiumisobtainedbyelectrolysisofaluminiumoxide
Aluminiumoxide
Aluminium+Oxygen
Corrosionofmetalsisoxida9on
• 
Mostmetalscorrode
• 
Surfaceofametalreactswithoxygen(orsome1meswater)
ThisiscalledOXIDATIONreac1on
Morereac9vemetalscorrodemorerapidly(lessreac9vemaynotcorrodeatalle.g.Gold)
Alayerofmetaloxideforms(thiscanstopfurthercorrosione.g.onAluminium=andAl2O3layer
• 
• 
• 
C1.19Recyclingmetals
Keywords
•  Recycledmetal–whenausedmetalismelteddownandmade
intosomethingnew.
Manymetalscanberecycled…
Advantages
•  Naturalreserveswilllastlonger
•  Mostuselessenergytorecyclethattoextract.E.g.Aluminiumrecycling95%moreenergy
efficientcomparedtoextrac1on.
•  Reducedminingwhichdamageslandscapesandcausespollu1on(dustandnoise)
•  Recyclingproduceslesspollu9on.Examplessuppor1ngthisare
•  Leadfromitsore‘galena’producessulfurdioxide
•  Carbondioxideisproducedduringextrac1onbyelectrolysis.
Disadvantages
•  Costsmoneyandusesenergytocollect,sortandtransportmetalstoberecycled
•  Thiscanmakeitmoreexpensivetorecyclesomemetalstheextractthem
ThemostrecycledmetalsintheUKareLead,IronandAluminiumandCopper
Method
1.  Collec1ng–requirespeopletobewillingtoseparatetheirrubbish
2.  Separa1ngdifferentmetals
•  Ironcanbeseparatedusingamagnet(quickandeasy)
•  Othersusuallyseparatedbyhand(1meconsumingandlabourintensive)
3.  Purifying–metalsaremelteddowntoformblocks
C1.20Proper1esofmetals
Proper1esinclude:–shinywhenpolished;
conductheatandelectricity;malleable;duc1le.
Keywords
Malleable–canbehammeredintoshape
Conduct–allowsheatorelectricitytopassthroughit
Duc9le–canbestretchedintowires
Density–themassofasubstanceperunitvolume;theunitisusuallyg/cm3
Aluminium
Copper
UsefulProper9es
•  Lowdensity
•  Doesnotcorrode
(becauseoflayerof
oxidethatforms
quickly)
Uses
•  Aeroplanesandcars
tomakethemlighter
(cheapertorunas
theyneedlessfuel)
UsefulProper9es
•  Duc1le
•  Lowreac1vity(does
notreactwithwater)
•  Goodelectrical
conductor
Uses
•  Electricalcables
•  Waterpipes
Gold
UsefulProper9es
•  Veryunreac1ve
•  Doesnotcorrode
•  Malleable
•  Remainsshiny
•  Excellentelectrical
conductor
Uses
•  Jewellery
•  Electronicdevices
(printedcircuit
boardsand
connec1onstrips)
IronandSteel
UsefulProper9es
•  Cheaptoextractby
hea1ngwithcarbon
•  Pureirontooso^but
inalloysisveryuseful
•  Steel(Ironmixedwith
carbonandother
metals)isstrongand
hard
•  Magne1c
Uses(mainlyassteel)
•  Bridges,cars,cutlery,
electricalgoods,
machinery,building
frames,magne1c
products
Keywords
Alloy–ametalmixedwithsmallamountsofothermetalstoimprovetheirproper1es
Carats–ameasureofthepurityofgoldwithpuregoldbeing24carats
Fineness–anothermeasureofpurityofgold(partsperthousand)
Smartmaterial–amaterialthat’sproper1eschangewithachangeincondi1ons
ShapeMemoryAlloy–analloythatcanreturntoitsoriginalshapewhenheated
C1.21Alloys
Puremetal
Puremetal
1.  Allatomsarethesamesizeandthereforecloselypacked
together.
2.  Thismeansthatlayersofatomsslideovereachotherwhich
makesthemetalsoh.
3.  Inanalloydifferentatomsareaddedwhichpreventtheatoms
slidingsoeasily=harderandstronger
ExamplesofAlloys
Alloysteels–ironmixedwithothermetals
•  StrongerthatIron
•  Someresistcorrosion.StainlesssteelNEVERcorrodes(IronwithChromiumandNickel)
Gold-Puregold(24carat)tooso^.24caratgoldhasafinenessof1000partsperthousand
•  Copperandsilveraddedtomakeitharder
Ni9nol–Smartmaterialmadefromnickeland9tanium
•  Returntooriginalshapewhenheated.
•  Usedinrepairofarteries(insertedinsquashedandcoldandwarmswithbodytoreshape)
•  Flexibleglassesframes
C1.22CrudeOil
Keywords
•  Hydrocarbonsarecompoundsthatcontain
carbonandhydrogenonly.
•  Crudeoilisacomplexmixtureof
hydrocarbons
C1.23CrudeOilFrac1ons
•  Crudeoilisseparatedintosimpler,more
usefulmixturesbyfrac1onaldis1lla1on.
C1.23CrudeOilFrac1ons
Thereare6frac1onsyouneedtoknow…
Frac9on
Uses
Gases
Domes1chea1ngandcooking
Petrol
Carfuel
Kerosene
Aircra^fuel
Dieseloil
Fuelforsomecarsandtrains
Fueloil
Fuelforshipsandsomepowersta1ons
Bitumen
Surfacingroadsandroofs
C1.23CrudeOilFrac1ons
Keywords:
Igni1on–tosetalight
Viscosity–Howthickorrunnyasubstanceis
Howdothefrac1onsdiffer?
Frac9on
Gases
Petrol
Kerosene
Dieseloil
Fueloil
Bitumen
Lengthof
molecule
Easeof
igni9on
Boilingpoint
Viscosity
Short
Long
Easy
Difficult
Low
High
Runny
Thickand
s1cky
C1.24Combus1on
Keywords:
Combus1on–achemicalreac1onwithoxygen(oxida1on)to
releaseenergy.
Completecombus1on–whereallthehydrocarbonisusedup.
Oxida1on–theaddi1onofoxygen.
+Energy
released
Anyhydrocarbon
Testedforusinglimewater.CO2
willturnitcloudyifpresent.
C1.25IncompleteCombus1on
Keywords:
•  Incompletecombus1on–wherethereisnotenoughoxygenforthefuelto
completelyburn.
•  CarbonMonoxide–poisonousgasproducedduringincompletecombus1on.
Waterisformedjustlikeincompletecombus1onbuttherearenotenoughoxygen
atomstoformCO2.SootandCarbonMonoxideareformedinstead.
3differentequa1onsshowwhatcanhappen:
Methane+OxygenàCarbon(soot)+Water
Methane+OxygenàCarbonMonoxide+Water
Methane+OxygenàCarbonDioxide+CarbonMonoxide+Carbon(soot)+Water
DifferentpercentagesofCO2,COandCareproduceddependingontheamountof
oxygenpresent.
C1.25IncompleteCombus1on
Problemsofincompletecombus9on:
•  CarbonMonoxideisanodourless,colourless,
toxicgas.
•  Itreducestheamountofoxygencarriedbythe
RedBloodCells.
•  Carbonmonoxidepoisoningcankill.
•  Sootcanclogpipescarryingwastegases.
•  Faultyorblockedboilerscanproducecarbon
monoxide.
C1.26AcidRain
Keyword:
Acidrain–rainthatismoreacidicthannormal.
Impuri1esinhydrocarbonssuchassulfurreactwithoxygento
producesulfurdioxide.Thisdissolvesinrainwatertoformacidrain.
4ProblemsofAcidRain:
•  Rivers,lakesandsoilsbecomeacidicharminglivingorganisms
•  Damagestrees
•  Speedsupweatheringofbuildingsmadeoflimestoneormarble
•  Corrodesmetal
C1.27ClimateChange
3gasestrapheatfromtheSunandkeeptheEarthwarm–GreenhouseEffect
•  CarbonDioxide
•  Methane
•  Watervapour
TheEarthstemperaturevaries.
Humanac1vitysuchasburning
fossilfuelsmayinfluencethis
C1.27ClimateChange
•  Theamountofcarbondioxideintheatmospherevaries
duetohumanac1vity–burningfossilfuels.
Howtoreducetheamountofcarbondioxideinthe
atmosphere:
•  IronSeedingOceans–Addingirontotheoceanencourages
algalgrowthwhichphotosynthesiseandabsorbcarbon.
Theyareeatenbyotherorganismswhichincorporate
carbonintotheirshellswhichsinkstothebo>omofthe
ocean.
•  Conver1ngcarbondioxidebacktohydrocarbons–trapping
gasesfrompowersta1onsandreac1ngthemtomake
butaneorpropanetouseasfuels.
C1.27ClimateChange
Keywords:
•  Correla1on–apa>ernwhichissimilarintwovariables.Itcouldbeduetochance.
•  Causa1on–whenonevariablecausestheeffectintheother.
• 
Thereisacorrela1onbetweencarbondioxidelevelsintheatmosphereandthe
Earthstemperature.
• 
Notallscien1stsareconvincedthatincreasingcarbondioxidelevelscauseglobal
warning.
Because…
•  Therearefluctua1onsthroughouthistory
•  Thereareothercausesofglobalwarning
•  Thereareothergreenhousegases
•  Futurepredic1onsarejustpredic1ons
C1.28Biofuels
Keywords:
Biofuel–Afuelmadebyhumansfromanimalorplantmaterialthathasrecently
died.
Ethanol–Afuelmadefromsugarbeetorsugarcane.
Biodiesel–Dieselmadefromplantmaterial.
Carbonneutral–afuelthatdoesnotaddanycarbontotheatmosphereoverall.
Biofuelsareapossiblealterna1vetofossilfuelse.g.ethanolwhichcouldreduce
demandforpetrol.
AdvantagesofBiofuels
DisadvantagesofBiofuels
Theyarerenewable
Growingcropsforfuelsrequiresland
thatcouldbeusedtogrowfood
Plantsremovecarbondioxidefromthe
atmosphereastheygrow
Transporta1onofthefuelsproduces
carbondioxide
Burningthefuelsproducescarbon
dioxide
C1.29ChoosingFuels
4factorsthatmakeagoodfuel:
•  Howeasilyitburns.
•  Howmuchashorsmokeitproduces.
•  Thecompara1veamountofheatenergyitproduces.
•  Howeasyitistostoreandtransport.
• 
Afuelcellcombineshydrogenandoxygentomakewaterandreleasesenergy.
Advantagesofusinghydrogenasafuel
Disadvantagesofusinghydrogenasafuel
Whenhydrogenburnsnocarbondioxideis
produced,onlywatervapour
Hydrogenusuallyproducedfromnaturalgasand
theprocessreleasescarbondioxide
Hydrogenfuelcellsaremoreefficientthanpetrol Hydrogenneedstobereadilyavailablefirst
engines
Renewable
Petrolsta1onswouldhavetobeconvertedto
storeandsellhydrogentoo
Costoftheabove
• 
• 
Petrol,Keroseneanddieseloilarenon-renewablefossilfuelsmadefromcrudeoil.
Methaneisanon-renewablefossilfuelfromnaturalgas.
C1.31AlkanesandAlkenes
Alkanesaresaturatedhydrocarbonswhichare
presentincrudeoil.
Learnthe
formula
andbe
ableto
draweach
ofthese.
C1.31AlkanesandAlkenes
•  Alkenesareunsaturatedhydrocarbons
Learnthe
formula
andbe
ableto
draweach
ofthese.
Brominewaterisusedtodis1nguishbetweenalkanesandalkenes
Ethene+brominewateràcolourless
(colourless)(orange)
Ethane+brominewateràorange
(colourless)(orange)
C1.32Cracking
Whyiscrackingneeded?Crudeoilhas
differentamountsofeachfrac1on.Thesedon’t
alwaysmatchcustomerdemandsotheycrack
themtomatchdemand.
Crackinginvolvesbreakingdownlongsaturated
hydrocarbons(alkanes)intosmallerusefulones.Some
ofthesesmallmoleculesareunsaturated(alkenes).
Knowhow
tocrack
paraffinin
thelab.
C1.33Polymerisa1on
Manyethanemoleculescancombineina
polymerisa1onreac1on.
Learntheformula
andequa1on
C1.33Polymerisa1on
4examplesofpolymersyouneedtoknow…
C1.33Polymerisa1on
Polymer
Proper9es
Use
Poly(ethane)–polythene
Flexible,cheap,good
insulator
Plas1cbags,plas1cbo>les,
clingfilm,insula1onfor
electricalwires
Poly(propene)–
polypropene
Flexible,sha>erproof,high
so^eningpoint
Bucketsandbowls
Poly(chloroethene)-PVC
Tough,cheap,long-las1ng,
goodinsulator
Windowframes,gu>ers,
pipes,insula1onfor
electricalwires
Poly(tetrafluoroethene)
PTFEorTeflon
Tough,slippery,resistantto Nons1ckcoa1ngsfor
corrosion,goodinsulator
saucepans,bearingsforskis,
containersforcorrosive
substances,stainproof
coa1ngforcarpets,
insula1onforelectrical
wires
C1.34ProblemswithPolymers
3problems
•  Mostarenotbiodegradable.
•  Theypersistinlandfillsites.
•  Theyproducetoxicgaseswhenburned.
Howcanweovercometheseproblems?
•  Recyclingpolymersinsteadoflandfill.
•  Developmentofbiodegradablepolymers.