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Steam Calculator - Superheated Steam. This page contains a steam table calculator and information on reaction rates, reaction equilibrium constants and chemical ... Products ProductsOverview MonthlyDeals EstimateSavings(ROI) MHIFinancing Airtorch™ProcessHeaters SuperheatedSteamGenerators e-IonPlasma™ Microheaters™ HeatingElements GAXP®Elements MolybdenumDiSilicide MagnaCoil™ SiliconCarbide FiberHeater Microtube™Heaters MicroIgniters Furnaces BoxFurnace HorizontalTube BottomLoading FrontLoading Vertical/SplitTube e-IonZapper™Furnace Accessories RobustRadiator™ Thermoplate™ GlowPanels™ HotTop™ ControlPanels GasPanels DataAcquisitionSystem ShopOnline MHIONLINESTORE SearchMHI GeneralInformation ConversionCalculator RadiationPowerCalculator EnergyEfficiencyGrantInfo OurNewsletter AboutMHI AboutMHI OurMission ScholarlyReferences LeaveFeedback Advantages Economics Testimonials CareerOpportunities UsefulLinks CommercialSteamCleaner MuffleFurnace ElectricSteamBoiler HighTemperatureFurnace SteamBoiler Temperature Converter Enteranumber&clickonthe"Calculate"button °F= °C   SteamCalculator-SuperheatedSteam Thispagecontainsa steamtablecalculatorandinformationonreactionrates,reactionequilibriumconstantsandchemicalprocessproductivityanalysis. Thesteamcalculatorwillgiveyouthetypeofphase(gasand/orliquid)atagiventemperatureandpressure. Thesteamcalculatorwillbeabletoprovidesaturatedconditionsandsaturatedproperties(atPsatandTsat)forachosenpressure. Thebasefortheenthalpyinthetablebelowisincompressiblewaterat0°C.   Forotherunits clickhere. Fordeterminingthekg/hr.forasteamgeneratorpleaseclickhere. Propertiesat PressureandTemperature Pressure Temperature Pressure Bar Temperature oC Enthalpy2837.92kJ/Kg Density4.802kg/m3 Entropy6.716kJ/Kg.KTemperature(Sat.)179.886oCSuperheat24.114oCPhaseSteam Pressure Kg/cm2G Kg/cm2A BarG BarA PSIG PSIA AtmG AtmAbs KPaG KPaAbs Temperature DegC DegK DegF DegR Enthalpy BTU/lb kJ/Kg KCal/Kg Entropy BTU/lb.F kJ/Kg.K KCal/Kg.C Density lb/ft3 Kg/m3 g/cm3 lb/in3 Calculation Units Howtoenhancetheindustrialproductionefficiencyofachemicalorionicprocess?   ShortAnswer:Increasethetemperatureoftheprocessgasorsteam. Why?Becausethisisoneeasymethodtodaytoincreaseproductivityandenergyefficiency? Whysaveenergy? MoreDetailedAnswer: Pleasereadon....forhightemperaturesteamandthenovelopen-ionicproducts.   Toenableanincreaseintheproductivityofachemicalormaterialsprocessingmethod,theojectiveistoincreasetheconversionrateofreactantstoproducts. Thetermindustrial-productivity,encompassesnotonlythechemicalkineticratebutalsoaspectsofthelong-termproductlife-cycleandotherimportanteconomicfactorsthatdefinethereactantandothersupplyprocesses(seealsoinnovationconstants).  Below,wefocusmainlyonthethetechnicalvariablesthatinfluencethisproductivity(sometimesalsoreferredtoasactivityintheproductivityliterature).    Asaruleofthumb,anincreaseintheproductivityofanheat-enabledfavorablereaction,measuredinthroughputincreaseperunittime(e.g.tonsperyear)maybeenhancedbytweakingtheprocessvariablesliketemperature,thepressureorenhancingheattransferrateswhereapplicable. ThefourbulletsbelowshowthattheproductivitycanbemainlyenhancedbyanincreaseintheTemperature(T),onlysomewhatbyPressure(P)andsometimeswiththeuseofagoodCatalyst. ThedirectionofanyreactionisinfluencedbytheEquilibriumConstant,K(definedbelow).Kisisathermodynamicpropertythusimplyingsomestrictboundariesforthepossibilitiestoinfluencethisnumberwithoutchangingothervariablesliketemperature.  Forchemicalreactionstheproductivitycanbeconsiderablyinfluencedbychangesintheimposedprocessconditions. Therateofreactioninvolvestheequilibriumconstantandafewotherkinetic'processingvariable'discussedbelow. Processvariablesareinitialtemperature,pressure,concentrationofreactantsandotherpertinentconditionslikethequalityofinsulation,feedbackcontrol-ability,goodsensorsandlike. OveralltheproductivityofaCommercialChemicalProcessisdefinedastheamountofproductmadebyanindustrialchemicalreactionplant(unitsoftons/year).  Improvementsinproductivityareachievedthroughimprovedoperation-researchoptimizationmethods,goodinternalbusinesspracticesandbesttechnicalconditionsthatkeepupwiththelatesttechnicalimprovementsinthermalandmaterialsavailability. Betterproductivitygenerallyleadstobetterenergyefficiency.Productivityandproduction-amountactivityareinterchangeableterminologies.ThesymbolsRandEbelowrepresenttheUniversalGasConstantandagenericactivationbarrierrespectively. R=8.314J/mol.K(0.0831bardm3mol-1K-1). ThecommonlyemployedunitforE,iskJ/molforchemicalreactions.    Themainfactorsthatinfluenceproductivityareshowninthehighlightedtablebelow. Productivityisincreasedby: •IncreasingtheTemperature.TheTemperatureimpactstheReactionRate,EnergyEfficiency,Heat-TransferRateandtheEquilibriumConstant.Thetemperature(T)speedsupaconversionexponentially,becausetheproductivityisproportionalto(Tø.e-E/RT).Thepowerlawexponentø,isaconstantapproximatelyequalto1butcouldbeashighas4forhigh-temperatureprocessing,particularlywhentransferringheatquicklywithe-ionsorveryhightemperaturesteam.TheCascadee-Ionplasmaisoneofthefastestmethodsofenhancingpowerintheheattransfermode. Theionsaugmentconvectiveandradiativeheattransport. Temperaturehasaninfluenceontherateofheattransfer,regardlessofwhetherthereactantsaresolids,liquidsorgasses. • IncreasingthePressure.ThePressureonlysomewhatincreasestheReactionRate,onlyinfluencingtherateinamannersimilartoareactantconcentration-change. PressurehasaverysmallornoinfluenceontheEquilibriumConstant, discussedfurtherbelow.Theimpactofpressureisrelatedtoachievingmorereactant(molecularlevel)collisionsperunittime,whichisapossibilitywhengassesareinvolvedinthereaction. Thereisalmostnoimpactofpressurewhennogassesareinvolvedinthereactionunlessoneisintheveryhigh10-1000Barrangeofoperationalpressures. • Increasingthethroughputwithimprovedtime-managementprocesses. Forexampleonepreferscontinuousprocessingoverbatchprocessingorchooseopensystemprocessingoverclosedsystemprocessing. Atemperatureincrease,shoulditbefeasible,stillhasthemostdominantinfluenceonproduction. Howeversuchanimpactisdependentonhowmanyyearsthatthecompanyhasbeeninexistence!...i.e. wherethecompanyisinit'slong-termcyclelife(long-termproductlife-cycle).  Notewhenconductedattheappropriatepartofthelong-termlifecycle,aplannedtemperatureincreaseisrelativelyeasierandcheapertoimplementwhencomparedtocertifyingandcreatinghighpressurecontainmentmethods. Onemayselectandscalethefeedrateforcontinuousreactorsabitmoreeasilythanforbatchreactors- againprovideditisatthepropertimeinthelifecycle. • Improvingthetemperatureuniformityandoptimizingthetypeofenergytransfermechanismforthedesireduniformity. Typicalenergytransfermechanismsofinterestarenormallyconvection,radiative,withae-Iontypesofenergytransfer/efficiencyenhancer. Usehybridthermalprocessesforbestoutcomeforenergyefficiencyandproductivity. Usingpreheatedreactantsisaproductivityenhancer.TheOABtechnologyisamoderntechnologyforhightemperaturesteam. GassescanbeeasilyheatedwiththeefficientAirtorchprocess-heatertechnology. SolidsandliquidsmaybepreheatedwithMagnaCoils,RobustRadiators,hightemperaturehotplatesorwithsafeenergy-efficientfurnaces.   Reactionratesincreasewhenthepossibilityofmakingreactantmoleculesencountereachotherquicklyisenhanced. Asdiscussedpictoriallybelow,inthereactionratesection,suchanincreasecanbeenabledinseveralways.Bothexothermicandendothermicreactionsratesareincreasedwhenthetemperatureofthereactionisincreased. ReactionratesincreaseexponentiallywithTemperature.Thebestavailablecatalystsshouldalwaysbeusedastheyimpactactivationenergy. Openprocessesi.e.steadystateflowisacontinuousprocess,arealmostalwaysmoreenergyefficientthanabatchprocess–e.g.highpressuresteambatch-sterilizationisslowerthancontinuoushightemperaturesteamsterilizationifitisallowed(note:thesteammustbeofacorrectandapprovedquality).Theuseofhighpressuresforopenprocessesisverydifficultandexpensive. Today,withtheadventofnewtransformativethermaldevices,likethee-ionandtheOAB,thetemperatureofprocessingcanbeeasilyincreasedevenforforopen-flowprocesses. Significantadvantagescanbegleanedforenergyefficiency.     EquilibriumConstantofaReaction.   Assumeahypotheticalreaction:aA+bB+mM-->yY+zZ+mM. HereZandYaretheproductspecies. AandBarethereactantspecies. Misaspeciesinerttothereaction. Achemicalreactionconservesmassandthetotalnumberofatomsofallelementsinvolvedinthereaction. Ifallspeciesaregaseouswewritethereactionwiththe(g)inparenthesestoindicategaseousspeciese.g.aA(g)+bB(g)+mM(g)-->yY(g)+zZ(g)+mM(g).Thelowercaselettersx,y,a,b,maremoles. Thearrowsignalsthedirectionofreactionthatisofinterest.    Thissamereactioninitsstoichiometricformmaybewrittenasa0A(g)+b0B(g)+m0M⇔y0Y(g)+z0Z(g)+m0M,thetwowayarrowindicatesthataforwardandbackwardreactionarefeasible. Thestoichiometricformisnotnecessarilytheequilibriummixture.    Whenatequilibriumi.e.a0e,b0e,y0e,z0earepresentofeachspeciesrespectively. Letusdesignatetheequilibriummixinitsmostgeneralformasa0eA(g)+b0eB(g)⇔y0eY(g)+z0eZ(g). Regardlessofhowwerepresentthereaction,thechemicalreactionconservestheinitialmassandthetotalnumberofatomsofallelementsinvolvedinthereaction. Theequilibriumcompositionsarenotknownapriori.Onlym0isknownandtheinitialamountsofAandBcanbeknownandthestoichiometricformoftheequationisknown.    Theobjectiveofchemicalreactionanalysisistofindtheequilibriumcompositionsorthedirectionofthereactionforaninitialmixofreactants. Fromthermodynamicsweknowthatthedirectionofareactionisdeterminedbyconditionsthatlowerthefreeenergyofaninitialmixbecauseoftheformationofmorethermodynamicallystableproductmix. Thedirectionofachemicalreactionisdeterminedbytheknowledgethatfortheequilibriummixofreactantsandproducts,thereactionwillneithergoforwardorbackwards. Inotherwords,atconstantpressureandtemperature,thetotalfreeenergychangebetweenproductsandreactantsofthereactioniszerofortheequilibriummix. Thefreeenergychangeisrelatedtotheenthalpyandentropychangebetweenproductsandreactants. Theheatofreaction(enthalpychange),DHrofcompoundscanbemeasuredorcalculatedfrombondenergiesorbyassigningstandardstatethermodynamicpropertiestoallelements.The entropiesofeachelementandcompoundsisalsoknown(seefreethermodynamiccalculator). Atconstanttemperatureandpressure,theequilibriummixforareactionisreachedwhenthetotalGibbsfreeenergychangebetweenproductsandreactantsiszero. Basedonthisconcept,anequilibriumconstant,KecorKp(seebelowfordefinitionsthatarebasedontherelationshipwiththeactivity)foreveryreactioncanbedefinedandisgenerallyknownforallreactionsbyassumingastandardstate(seebelow)i.e.abaselevelfromwhichallchangesaremeasured. Theequilibriumconstantcanbecalculatedfromaknowledgeofsuchfreeenergiesofthereactantsandproductsatthereactiontemperature.  Freeenergiesaremeasurefromastandardstate(againseebelow). Onceknown,itcanbeusedtocalculatetheextentofareactionthatispossibletoreachequilibriumconditionsandthecompositionmixatequilibrium. Theequilibriumconstantthusisaveryusefulnumberbecauseitquicklyindicateswhetherareactione.g.thedesiredforwardreactionforexampleaboveispossibleornot,andhowmuchproductmaybeexpectedfromachosenreactantmixwhenthereactionreachesequilibriumorundersteadystateconditionsiftheproductsarecontinuouslyremovedandreactantsarecontinuouslyadded.Theequilibriumconstantallowsforthedeterminationofy0e,z0einthereactionabove,whenm0isknownandtheinitialamountsofAandBareknown. Forthederivationsbelowtoillustratethedefinitionoftheequilibriumconstant,wewilldropthe subscriptsoe. TheKec(chemistrytextbooksusethesymbolKc)orKpvaluesaretabulatedandwellknownforalmostallchemicalandbiologicalreactions.TheEquilibriumConstantisthepowerratioofactivities(e.g.aY)(shownbelow)ofproductsoverreactantsforareactionthatisatequilibrium. Theequilibriumconstantexpressionisdefinedas: Kec={aY}y0{az}z0/{aA}a0{aB}b0   Theactivitiescanbewrittenintermsofmolefractions,moles/Lorpartialpressureratios. ThegaseousreactionequilibriumconstantKp,isexpressedbypartialpressureratios.   KP={PY/P0}y0{Pz/P0}z0/{PA/P0}a0{PB/P0}b0   HereP0isathestandardstatepressure(normally25C,1atmosphereischosenforchemicalreactions)andPYisthepartialpressureofgasYdefinedasPY=(y/NT)PTwherePTisthetotalpressureincludinganyinertconstituentsinthegasmixtureandtotalnumberofmolesisNTincludinganyinertconstituentsinthegasmixture. ThepartialpressurePz,PA,PBaresimilarlydefined.   ForidealgassesaY=PY/PT. ForpuresolidorliquidsaY~1. ForsolutionsaY=gYxY. WheregYiscalledtheactivitycoefficient(rangesfrom0to1;itiscloserto1forhighconcentrationsandhightemperature),andxYisthemolefractionwhenincludingallinert species. Activitycoefficientsinthestandardstateare,bydefinition,equalto1.   Whenexpressedinmoleconcentrationsi.e.mol/LtheequilibriumconstantisgivenasKec=[CY]y0[Cz]z0/[CA]a0[CB]b0 herethesquarebracketscorrespondtoconcentrationinmoles/LwhereListhesymbolforliter. 1dm3=1L. 1000mol/m3=1M(molar).  CY=(Ny/NT).Nyo/VwhereVisthevolumeoftheequilibriummixtureandNyoisthestandardstatemolesofthespeciesY(equalto1).Cy=PY.Nyo/Vy0whereVy0isthestandardstatevolumeandNyoisthestandardstatemoles. Thedensityofwateris~1000g/Landitsmolarmassis18.02g/mol(or1/18.02=0.055mol/g).Therefore,themolarconcentrationoffor1LofwaterisC(H2O)=55.5mol/L. Otherunitsmaybeused. Theconcentrationmaybeexpressedasmassperlitere.g.forwater1000g/Lormasspermolese.g.forwater18.02g/mol. BelowwewillusethemolesperLdefinitionformolarconcentration. SubstitutingCY=(Ny/NT).Nyo/VintheKpequationaboveyields aKecnumberfortheequilibriumconstantwhere   Kec={(CY/P0).Vyo/Ny0}y0{(Cz/P0).Vzo/Nz0}z0/((CA/P0).Vao/Na0}a0{(PB/P0).Vbo/Nb0}b0   WithP0=1barandNyo/Vyoandallothersimilarspecies-relatedquantitiesequalto1Molar(1mole/L),theequationfortheequilibriumconstantabovetakesthefamiliarform   Kec=[CY]y0[Cz]z0/[CA]a0[CB]b0   whenCisthemolarconcentrationandthusKec={Kp/(PT)∆n0}. NotethatwehavedefinedCy=PY.Nyo/Vy0andtakenP0 =1barandNyo/Vyoandallothersimilarspecies-relatedmolarvolumeisequalto1Molar(i.e1M).   Kecx={[PY/PT]y0[PZ/PT]z0}/{[PA/PT]a0[PB/PT]b0}=[Kp{(P0)∆n0/(PT)∆n0}]   where∆n0=(yo+zo)–(ao+bo)i.e.(numberofmolesofgaseousproducts–numberofmolesofgaseousreactantsforthestoichiometricformofthereaction)i.e.inthebalancedchemicalreaction.ThesubscriptxinKecxindicatesthattheequilibriumconcentrationisformolefractiontypeconcentration.    TherelationbetweenKpandKecx(sameasthesymbolKx,sometimesemployedinchemistrytextbooks)isgivenas: Kp(P0)∆n0=Kecx(PT)∆n0=Kecx(NTRT/V)∆n0 foravolumeV(rememberthemolarvolumeofanidealgasissameregardlessofthegasandalsoemphasistheusethecorrectformofRe.g.ifPisinbarthenaformofRcouldbe0.0831bardm3mol-1K-1)(ifPisinPatheR=8.314J/mol.K). Notethat1bar~100kPa. NT/Visthemolarvolumeoftheidealgas.Chemicalconcentrationsarethesameasmolarconcentrationsinmoles/L.  Forgases,especiallyforidealgasses(thatisdescribedbyaEquationofStatePV=NRT)theEquilibriumConstantKpisnotafunctionofthetotalPressure. Theequilibriumconstantwillremainthesameforeachreaction,independentofinitialconcentrations.TheKecchangeswithtemperature.   Foranygiventemperature,thereisonlyonevaluefortheequilibriumconstant.Kec(ormorecommonlyreferredtoasKcwhenweexpresstheequilibriumconstantasaratioofconcentrations)onlychangesifthetemperatureofthereactionchanges. IfKec>1thenitfavorsproductformation. InfactifKec>1000thenyoufindmostlyproductsi.e.ifyoumixAandB,theyreactalmostcompletelytobecomeproductwhenKec>1000. IfKec<1thenitfavorsthereversereaction.   Thedependenceoftheequilibriumconstantwithtemperatureisgivenbythevan'tHoffequationwhichhasadifferentialformandanintegralformi.e.eitherexpressedasd(ln(Kec)/dT=DHr/RT2 oras ln(Kec)=-DHr/RT+(a constantofintegration). IncreasingthetemperaturewillincreaseproductionoutputbecauseofanincreaseinKec(theequilibriumconstant)wherepossible,butmoreimportantlyfromthesignificantreactionrateincreasethatoccurs(e.g.enabledwithanOAB)whenthehighestthroughputtechniqueandthecorrecttemperaturearechosenforthereactantsteam. Regardless,otherconsiderationsforacommercialprocessmayoftenexistwhichhavenothingtodowiththereactionkinetics,andamulti-stepprocessmayforexamplebenecessitatedforareactionproduct(seehttp://en.wikipedia.org/wiki/Equilibrium_constant). Insuchcasestheusehybridthermalprocessingisonetechniquesgetthebestoutcome.Aknowledgeofequilibriumconstantsisessentialfortheunderstandingofmanychemicalsystems,aswellasbiochemicalprocessessuchasoxygentransportinbloodorotherredoxreactionsinthehumanbody. AssumeagainaA+bB-->yY+zZ;withaHeatofReaction>0(endothermicDHr>0).  Ifnetheatisrequiredtoinspirethisreaction(endothermic),thenanincreaseintemperaturecausesanincreaseintheproductsconversionforthereactionbecausetheKecincreases.  Almostalwayswehavetoenableprocesseswiththeadditionofheatwhethertheyarechemical,melting,sintering,rolling,forgingor ionizationprocesses. Inotherwords,processesareendothermicforalmostallcommercialobjectives. Evenifexothermic,theprocessesmaypresentanactivationenergybarrier(discussedbelow)whichneedstobeovercomebyahigherreactanttemperaturebeforethereactioncangoforward. InordertocalculatetheamountofYandZ(products),theequilibriumconstantisallthatweneedonceweknowtheamountsofAandB(thereactants). Example:Considerthereaction: C(s)+H2O(g)⇔H2(g)+CO(g).Thethermodynamicequilibriumconstantforthisreactionis~6.5x10-19at298K. Thevalueoftheequilibriumconstant(Kecx)attwohighertemperaturesisgivenbelowforthisreaction. NotethatKincreasesdramaticallyfromlessthan1toabove1withanincreaseinthetemperatureforthisendothermicreaction. Temperature 430C(806F)   Kecx~=5x10-5 Temperature700C(1292F) Kecx~=1.5 FormoreinformationonequilibriumconstantexpressionsandtablespleasevisittheWikipediasite:http://en.wikipedia.org/wiki/Equilibrium_constant.  ExampleswhereH2Oisaprocesschemical: Hydrogenisusedinammoniamaking,acidmaking,petrochemicalsandasfuel(includingfuelcell).TheUnitedStatesaloneproducesmorethan10milliontonsofhydrogenperyear. Thefollowingexamplesareforsteamreactionsarepossibleforhydrogenmanufacture. 3Fe(s)+4H2O(g)⇔Fe3O4(s)+4H2(g) FromknownthermodynamictablesKcat500Cforthisreactionis5.218E+002whichimpliesthatatthistemperatureplentyofH2ismadei.e.theforwardreactionisfavored. ConcentrationsofFeandFe3O4areomittedincalculatingKp.Althoughtheconcentrationofagascanhavevariousvaluesdependingonpartialpressure,theconcentrationofapuresolidorapureliquidisaconstantatagiventemperature.Theconcentrationofliquidsolventisusuallyomittedaswell. Forthereactionofironwithsteam,youwouldwrite Kp=PH24/PH2O4andgetthePH2value.  Thereaction2Fe+3H2O(g)=Fe2O3+3H2(g)doesnotgoforwardabove600C.  ThereactionFe+H2O(g)=FeO+H2(g)isveryweakby1000C asisthe3Fe(s)+4H2O(g)⇔Fe3O4(s)+4H2(g)reaction.Inordertomakehydrogenwithsuchreactionsitisimportanttofindthehighesttemperaturewherethereactionremainsveryfavorableaswellasshowthebestkinetics.  Amorecommonlyemployedreactionformakinghydrogenisthemethanesteamreformingreaction(MSR),CH4+2H2O⇔CO2+4H2forcommercialbulkhydrogenproduction.SteamReformingcanbethoughttooccurintwosteps,namely: CH4+H2O⇔CO+3H2[ΔH=+206kJmol-1] CO+H2O⇔CO2+H2[ΔH=-41kJmol-1] ________________________________________________ CH4+2H2O-->CO2+4H2[ΔH=+165kJmol-1]Endothermicthusrequiringhightemperatureforbothgreaterandfasterconversion. ThisreactioncanbefavorablymanipulatedwithOAB(R)hightemperaturesteam.   Steam/Waterisemployedasachemicalinthephotosynthesisreactiontomakesugarorsugar-likecompounds.  Althoughwritteninasimplereactionmanner(6CO2+6H2O>C6H12O6+6O2)thereactionisquiteacomplexreaction. Thisreaction,calledphotosynthesisoccursinplantswiththehelpofsunlight(photons)anduseschlorophyllinthe plantcellchloroplasts.Chloroplastsaresmallmolecularobjectsthathaveveryspecificfunctioninacell. Chloroplastsarefoundinplantcellsandsomeothercellularorganisms. Duringphotosynthesis,chloroplastscapturephotonsandstoretheenergyofthephotonsintheenergystoragemoleculesATPandNADPHallthewhilereleasingoxygenfromwater.TheythenusetheATPandNADPHtomakeorganicmoleculesfromcarbondioxideinacyclicprocessknownastheCalvincycle. Thiscyclerequirestrappingofsunlightenergyduringapartofthecycle. Ongoinge-ionandOABresearchisdirectedatusingphotonsandelectronstopossiblysimulateand/oraidthesugarsynthesisorsequestertheCO2. Howevertheresearchisataveryearlystage.    TheE-IonCascadeisrevolutionizingthewaynitrogenisusedbyprovidinganalternativeroutetoHNO3,whichavoidstheNH3intermediate,isdirectNitrogenoxidationtoaqueousHNO3  N2(g)+2.5O2(g)+H2O(liq)=2H+(aq)+2NO3−(aq) Theequilibriumconstantforthisreactionis∼2.7×10−3M4/bar3.5(StandardGibbsFreeEnergyΔG0=14.6kJ/molN2)   Yetanothercommonsteam/waterreactionisdissolvingCO2inH2Oandconsequentlyformingaweakacid(bubbly). Thisreactionisnotthesameasthephotosynthesisreactiondiscussedabove.Thedissolutionreactionisusedformakingsodaandsodadrinks.Thereareothersimilarreactionsbetweenelementswheremorethanonecompoundcanbemade.Thelawofmultipleproportionsthenapplies. Fortheforwardreactiontodominate,theequilibriumconstanthastoexceed1. FortheMSRreaction,theequilibriumconstantincreasesabove1onlywhenthetemperatureexceeds864K. At1000°CKec=4963whichisveryfavorableforcompleteconversiontohydrogen shouldthatbetheobjective. Newsuperheatedsteamgenerationdevicesprovideinstanthotsteamtobemadeavailableforthisandsimilarreactions.  ThereactionC+ 2H2O-->CO2+2H2hastobeabove966Kforthereactiontobecomefeasiblefortheforwardreaction. MHIalsooffersairheatingforcombustibleandnon-combustiblegasses. Otherreportedusesusesforhightemperaturesteamareinsteamhydrogasification,orinchemicalprocessequipmentforheattransferfromsuperheatedsteamtoareactorchamber. ForthefirsttimebycombiningOAB'sandRobustMHIfurnaces,steamboxesupto1700Cinboththecontinuousandbatchmodesarenowavailable. ReactingFewithsteamisonewayofproducingH2.   Yetanotherhydrogenproducingreaction,whereCOreactswithH2Oisanexothermicreaction(seeallthewaybelowforschematicsofexothermicandendothermicreactions). CalledtheGasReactionforHydrogen,thisreactioncanbeusedtoillustratehowtheKchangeswithtemperatureforanexothermicreactionwhereonemoleeachofCOandH2O(reactants)produceonemoleeachofCO2andH2(products).  NotethatthetemperatureisinKelvinandthedirectionofthereactionisasshown. Notethelogarithmicscaleofthey-axisfortheequilibriumconstant.       IonicReactions   Whenspeakingofionicreactions,therearetwocommontypes: (a)theaqueousionictypeand(b)thenon-aqueousionictype. Severalstandardchemistrytextbookspresenttheaqueoustypeverycomprehensively. Thenon-aqueoustypeismostlyrelatedtoionicgasesandionicgas-solidreactionsandthereportsarefewandfarbetween. Howeverthesearetheonesthatareindustriallyveryvaluableforcreatingcoatings,diamonds,barriersandanticorrosion,andantiseizesurfaces.   Theaqueoustype:Anionicequationisachemicalequationwheretheelectrolytesinaqueoussolutionarewrittenasdissociatedions. Themostimportantreactionisthedissociationofwateri.e.2H2O=H3O++OH-wheretheH3O+isthehydroxoniumionandOH-thehydroxideion. Thesquarebracketsareconcentrationexpressedinmoles/liter. TheequilibriumconstantforionicreactionsisgiventhesymbolKw. Forthewaterdissociationreactiontheself-ionizationequilibriumconstantisKw=[H3O+][OH-]=10-14at296.5K. WatermoleculesdissociateintoequalamountsofH3O+andOH−,sotheirconcentrationsareequalto1.00×10−7mol∙dm−3(dm-3isaliter)at296.5Kand0.1MPa. Notethatthewaterdissociationequilibriumconstantisaverysmallquantity. AsolutioninwhichtheH3O+andOH−concentrationsequaleachotherisconsideredaneutralsolution.Whenthe[H3O+]concentrationishighthepHislow(acidic)andforthesameequilibriumconstantKw,thethecorresponding[OH-]islow. ThepHofaneutralsolutionat294.5Kand0.1Mpa,ispKw/2=7wherepKw=-log{[H30+][OH-]}.Theself-dissociationionicreactionisanendothermicreaction. FollowingtheVan'tHoffrulediscussedabove,theselfdissociationincreaseswithincreasingtemperature. ThereforethepHnumberdecreaseswithtemperatureasdoestheneutralpoint. WhenthereisanabundanceofH3O+formation(forthesameKw)thenthesolutionisconsideredaverystrongacid. AlthoughapHofclosetozeroreflectsanextremelystrongacid,thepHscaleisnotaveryusefulscaleforextremelystrongacidssuchas2MHCl.  Whenwaterismadeintogas(steam),thendissociatingthegasintoatomsorfurtherintoions,isverydifficult(seetablebelow)unlesstheLIPorothermeansisusedforionization. ThetemperaturethusdecreasesthepH(notepHisthe-logoftheH+concentrationwrittenaspH=-log[H+],ormorecorrectlythe-logoftheH30+concentration). PressuredecreasestheKwnumberforthewaterself-dissociationreaction.Athousand-foldincreaseinpressurewillreduceKwtoabout10-13. ThevalueofKwisusuallyofinterestfortheliquidphasedissociation.Examplevaluesforsuperheatedsteam(gas)includingforsupercriticalfluidaregiveninthereferencehttp://en.wikipedia.org/wiki/Self-ionization_of_water.   Otherexamplesofaqueousionicreactionsaree.g.Ag+(aq)+NO3-(aq)+Na+(aq)+Cl-(aq)→AgCl(s)+Na+(aq)+NO3-(aq),anionicequationofthechemicalreaction:AgNO3(aq)+NaCl(aq)→AgCl(s)+NaNO3(aq). Thenon-aqueoustypeofionicreactions:Withtheadventofthe Cascadee-iontechnology,easyionizationisnowofferedbyenergyefficientsteady-flowdevices.  Apositiveionisachemicalspecies(chemicalatomminuselectron)i.e.anelementseparatedfromatleastoneofitselectron. Anegativeionhasatleastoneextraelectroncomparedtotheneutralspecies. Usingeasilymadecascadee-ionshasopenedanewwindowtoanundiscoveredrealmofchemicalandmetallurgicalreactionswithextremelyhighproductionrates. Moredetailsareavailablebyclickingonnewtransformativecommercialionandelectronmakingdevices. Withthethee-ionrapidkineticscanbeinvokedtogivecleanshinyaluminum,copperandothermetallicfinishes. Ammoniacanbemade. E-Ionmachinessaveenergyastheyuseonlyairtocreatebiomedicalandhardtoolbitsurfaces. In fact,oneofthebiggestbreakthroughsforaluminumdrossreductioncomesfromusingathermallyionizedair-coveroveramelt.  Ionicdeburring,peeningandsuchreactionsarebeingdiscoveredforanti-seizeandanti-corrosionusewiththeCascadee-Ion.Thee-iontechnologyhasalsoloweredthecostofcleaningVOCcontaininggassesperpoundofgascleaned. Ionicreactionscanbeusedtocreatediamondfilmsorotherhardfilmsonsubstratesbyusingtherightprecursors.  Asingle15kWunitofane-ionreducesdrossinaluminum,bismuth,zinc,lead,silverandothermaterials. Surfacechargeandwettabilityofplasticscanbechangedinafractionofasecond. Suchchangesinfluencetheantimicrobialcharacterofthesurface. IonizationisoftenreportedineV/atomandchemicalreactionsinkJ/mol. Theconversionis:   1eV/atom=23.069kcal/mol=96.521kJ/mol    Typicalionandbosonorfermionreactionswithmoleculesareclassifiedtypicallyintothesixgroupslistedbelow. A^indicatesactivatedspecies.   e−+A2−→2A^+e− e−+A2−→A^2+e− e−+A2−→A++A−+e− e−+A2−→A+2+2e− e−+A2−→A−+A^ e−+A2−→A++A+2e−   Withionicreactionswhereaircanbeionized,themostimportantbreaktroughmaybethatsimplehighspeedtooldrillsandtoolbitsandtappingdrillscanbemadetohaveaveryhard,smoothandant-gallingcoatingwithextremelygoodcoefficientoffrictionthuscuttingmachiningspeedssometimesbyhalf. Moreaboutbosonandfermion devices.   Hydrogenperoxideoftenfiguresinmanyionicreactions. Thiscompounduniquelyisabletoactasanoxidizingagentorareducingagent. Whenitactsasareducingagent,oxygengasisproduced. ItcanalsoactasanoxidizingagentforexamplefortheoxidationofferrousoxideFe2+totheFe3+oxidationstate. IonizedH2Oisnowofferedbyaspecial e-ionmachine. IonizedH2Oappearstobeparticularlyusefulforcreatingantibacterialplasticsurfacesalthoughtheteststodateareonlyofalimitednature.   Thebenefitsarebeingdiscoveredonadaily basis. Cascadee-IonseasilyionizeHelium,Argon,forminggas(Ar+H2),andmostimportantlyair toformingareducingplasmaplume. IntimephysicistsandchemistswilldiscovertheexactnatureoftheCascadee-IonplasmaanddeterminewhethertheSaha-LangmuirequationsarevalidandhowtheTownsendavalanches,impacttheCascadee-ionplume.  Muchistobelearnt. ThecompanyMHIInc. whichhasinventedtheseplasmasystemshasalsomadethemavailableatafractionofthepricecomparedtootherindustrialplasmasystems.   Howtomakearustedpart,betterprotectitselffromcorrosion,afteritshowscorrosion(i.e.looksredandrusted)? Trytocleanitandapplyanoncorrosivepaint. IftheapplicationismoredemandingandmayneedtobeusedatahighertemperaturethenonewayistoemploytheSEmodeoftheCascadee-Iontoeasilytreattherustedpart. Althoughmicrostructuredetailsarenotyetfullyunderstooditdoesappearthat ensuringthatFe3O4(s)areionicallyfused-incomparedtoFe2O3(s)alongwithcertaincompoundnitridephases. SuchsurfacesareenabledbytheCascadee-ionintheSEmodeaboveacertaintemperatureasdiscussedaboveforsteam. TheCascadee-ionfurtherallowsoxynitridestoformwhichimpartsignificantsmoothnessandlessseizing.   ReactionRatesforExothermicandEndothermicProcesses.   Variablesthatincreasetherateofareactioni.e.thetechnicalproductivityincludethespecificspeciesofthereaction,thespecificactivatedspeciesthatformduringthereaction,thereactantconcentrations,surfacearea,temperature,life-cycleplacementandcatalysts.   Differentreactantswillhavedifferentreactionratesbecauseofthedifferencesintheactivationenergybarrier,Ea,foreveryreaction(seebelow). Theinitialconcentrationsand otherinitialconditionsliketemperatureandpressurewillinfluencethereactionpathwayandthusthenetactivationenergyencountered. Thesize,distributionandshapeofreactantmoleculeswillalsoinfluencetheoverallEa. Morereactants(input)resultinmorecollisiongivingrisetoafasterproductionrate(throughput). Anincreaseintheamountofreactantscanbeenabledbyincreasingtheconcentrationofthereactants(sameasincreasingthepressurewhengassesareinvolved). Veryoften,reactionsneedasurfaceonwhichthereactioniseasierenabled. Insuchinstancesahighsurfaceareagivesagreaterchanceforthereactantstoformproduct(s). Ahighertemperatureofreactionwillresultinmoreenergeticcollisions. Seebelowformoreinformationonreactionrateconstantandenergyefficiencyasafunctionoftemperature. Catalystsaremetalsandcompoundsthathelpthereactionratebyloweringtherequiredactivationenergyforareaction. Oftentheyresideonthesurfaceonwhichthereactionoccurs. Optimizedconditionsintheoveralllife-cycleplacementofaprocesssignificantlyinfluencestheproductivityasdiscussedabove.   Forareactiontooccuratacertaintemperature,aninitialactivationenergybarriermayrequiredtobeovercome. Reactantshavetocollidetoproduceproductsandbecausethisisaratelimitingstep,chemicalreactionsencounterabarrier.  Pleaserefertothefiguresbelowforapictorialdescriptionandananalogy. TheActivationEnergyBarrier,Eaistheminimumenergythatareactantmixmustpossessinordertoconvertthereactantstoproducts. Thisactivationbarrier(Ea)candeterminehowfastareactionoccurs.  Thehighertheactivationbarrier,theslowerthereactionrate. Thelowertheactivationbarrier,thefasterthereaction. Considertheanalogousprocessofsomeonetryingtorollaboulderoverahill. Thehigherthehill, theslowerthetask. Thelowerthehill,thefastertheprocess. Theheightofthehillisanalogoustotheenergyofactivation(Ea)thathastobeovercomeforareaction.   Assumeagainahypotheticalreaction:aA(g)+bB(g)⇔yY(g)+zZ(g). Assumeweareonlyinterestedintheforwardreactioni.e.aA(g)+bB(g)-->yY(g)+zZ(g)i.e.weareinterestedintheproductionofZandYastheobjective. AssumewearefurtherinterestedinproducingZandYasquicklyaspossibleinordertohavethehighestproductivity(productionrate).Theapplicablerateequationisnowdiscussed(linktoexampleforoxides).   RegardlessofbeingexothermicorendothermicthereisaninitialbarrierEa,toovercomefortheforwardreaction. Increasingthetemperature ofthereactionisthesameasprovidinghigherenergy(temperature)reactants.Thedifferencebetweenanexothermicandendothermicreactioncanbeillustratedbythehill/boulderanalogyillustratedbelow. Afterreachingthetopofthehilliftheboulderrollstoa heightlowerthantheoriginal,itwillpossessalowerpotentialenergythanatthestart. Thedifferenceinenergyis thenetgainofenergyfromtheprocess-notetheanalogywithanexothermicreactione.g.H2+1/2O2=H2Ointhediagramsbelowwherethereisaheatreleasebecausesomebondsarebrokenandothersmadeorremade. Ifontheotherhandthebouldercomestoarestatahigherlevelthanthestart,thedifferenceinenergyistheamountsuppliedduringtheprocess. Theendothermicreactionanalogywhereapartofthissupplyofheatenergyiscapturedinthenewchemicalbondse.g.CH4+2H2O-->CO2+4H2andhighertemperature,illustratedbythethickverticallineintherighthandsidefigurebelow.  Regardless,forbothexamples,Eaistheamountofenergytobeovercomeandneedstobeinitiallymadeavailabletothereactants. Forbothexamples,thefreeenergychange(workrequiredtocarryoutareaction)hastobefavorable(strictlyatleastforonesub-reactionifthereareseveralsubreactionsintheoverallreaction). Whenthenetfreeenergychangeisnegative(thereactioncanproducework)thereactioncanbespontaneous,yetmaystillneedtoovercomeanactivationenergybarrier. Whenthefreeenergychangeispositivethereisanetenergypenaltywhichmaybelowerthantheactivationbarrier.   Althoughtheoverallproductionexpressionisoftheformgivenallthewayatthetopofthispage,notethatamajorpartoftheratecouldbefromthecommonlyunderstoodreactionrateequation. Thesymbolmostoftenemployedfortherateconstantislowercasek.Thereactionrateequationforachemicalreactionis proportionaltoe-Ea/RT.  Therateofreaction,ineitherreactiondirection,isrelatedtotheinitialconcentrationraisedtoapowerthatreflectstheorderofreaction,multipliedbyapre-exponentialconstantk0andfurthermultipliedbye-Ea/RT.  Eamaynotbestronglyinfluencedbytemperature,butkisexponentiallyincreased(verystronglyinfluenced)byanincreaseinthetemperature. Thee-Ea/RTpartoftherateconstantdoesnothavedimensionsbuttheamountmadeperunittimee.g.Kg/hr,isproportionaltotheinitialstartingamountandtok0;andthusscaleswiththetemperature.  Catalystsareusedtoessentiallyreducetheeffectiveactivationbarrier(Ea)foranyreactionbyprovidinganewreactionpathwaythathasalowerorsmallerbarrier(notethatanapparoximateanalogywiththeboulderexamplecouldbemakingthehillsurfacesmoother). However,catalystsmayfoulovertimeandareoftenveryexpensive(manycatalystscontainexpensivenoblemetalslikeplatinum). Increasingthetemperatureisthusoftenthebestbetonacostbasistoenjoyhigherproductivity.   ThecommonlyusedunitsforEaarekJ/moleorlesscommonlyusedarekJ/(volumeunits).Ristheuniversalgasconstant. EaisabarrierthatneedstobeovercomeandRTisathermal"help'energyterm. TheratioEa/RTisdimensionless. NotethatTisthetemperatureinKelvin. Eaisatermwhichhastheorderofenergyrequirementofchemicalbondenergies. Chemicalbondshavebondenergiesintheorderof10-100kJpermolewhereasRis8.314J/mol.K. ThevalueofRTonlyaboveT>1000KbringstheRTtermintotheorderofmagnitudeofcommonchemicalbondenergies. Thepre-exponentialpart,k0(withunitsoffrequencyi.e.1/s)isalsoafunctionoftemperature. Itincreaseswithtemperatureinaclose-to-linearrelationshipaccordingtoatheorycalledtheactivatedspeciestheory. NotethatEamaysimplybetherealendothermicenergyrequirementforareaction,ifanactivatedcomplexisnotrelevanttothereactionsequence. Howeveralmostalwaysaactivationenergycomponentexceedingthetotalthermodynamic-barrierrequirementisrequiredtostartandkeepareactionongoing. Ionicreactionsareparticularlyinterestinginthisregardandwillbediscussedinalaterchapterofthismodule. Forcompletionweshouldalsonotethatoscillatoryreactionscanbeset-offbecauseofkineticratedifferencesinsub-reactions. SomeofthesetypesofreactionsarecalledBZreactions. Suchoscillationswhenpresentofferanabilitytoalterthetypeofthefinalproductbasedontheinitialtemperaturechoicemade.   Againonemaybeabletosenseananalogyfromthecommonexperienceoftryingtopushaboulderoverahill.  Thehighandlowbarrierdefinitionsarerelative(thinkoftheanalogyofheightandsurfaceofthehillvs.themightandwillofthepersonpushingtheboulder).  Forthesamehillheight,alowersurfaceresistance(friction)andgreaterwillpowermakesiteasiertopushtheboulderupthehill. Inasimilarmannertheactivationenergyhoweverlargeisovercomewhenthereactantsareproperlyenergizedwhichiseasytodowithtemperature. Becausee-Ea/RT=1/eEa/RT,notethatthisexponentialtermisalmostzerowhentheexponentislargei.e.(Ea>>RT). Theexponentialtermisalmostmaxedoutatonewhen(Ea<