1. 2....The Haber-Bosch Process 2. Keq The Haber-Bosch Process Almost all of the world’s ammonia...

Chemistry12EquilibriumIII

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1. TheHaber-BoschProcess2. Keq

TheHaber-BoschProcessAlmostalloftheworld’sammoniaisproducedviatheHaber-Boschprocessandalmostallofourinorganicnitrogencompoundsareproducedfromthisammonia.Morethan100milliontonnesofammoniawithavalueinexcessof$600millionareproducedannually.About80%oftheworld’sammoniaisusedtoproducefertilizers.Otherproductsincludeexplosives,plastics,fibresanddyes.GermanchemistFritzHaberdevelopedtheequipmentandproceduresfromproducingammonia(NH3)fromitsconstituentelements(N2andH2)in1910.In1918,hereceivedtheNobelPrizeinchemistryforhisaccomplishment.In1931,anotherGermanchemist,CarlBosch,wontheNobelPrizeinchemistry,inpartfortransformingtheprocesstoanindustrialscale.Thebalancedequationandenthalpyforthereactionare: N2(g)+3H2(g)⇋2NH3(g) ΔH=-92kJ/molTheEquilibriumConstantConsiderthefollowingequation:

N2(g)+3H2(g)⇋2NH3(g)

Atequilibrium,theforwardandreverseratesareequal.Forwardrate:

Reverserate:

Rearrangingtoisolatetheconstants,weget:

Inthiscase,kfkrprovidesaconstantthatchemistscalltheequilibriumconstant,Keq.

Keq=

dependent on C s dependent onof reactants CIs of products

edm kfCNz CHIP KrcNHz2

Isso

ingeneral Cprodects ratio w

reactants knits

Regardlessoftheinitialconcentrationsofreactantsandproducts,whenequilibriumisachievedandtheequilibriumconcentrationsaresubstitutedintothisexpression,thecalculatedvaluewillalwaysbethesame.

Theequilibriumlawstatesthatforthegeneralbalancedequation:wA+xB⇋yC+zD

wherew,x,yandzarecoefficientstobalancetheequation.

Balanceandwritetheequilibriumexpressionforthefollowingreactions:___C2H2(g)+___H2(g)⇋___CH4(g)

___SO2(g)+___O2(g)⇋___SO3(g)

___HCl(g)+___O2(g)⇋___Cl2(g)+___H2O(g)

___CH4(g)+___H2O(g)⇋___CO(g)+___H2(g)

1.Thefollowinggasesareatequilibriuminaflaskat423oC:4.56x10-3MH2,7.4x10-4MI2,and1.35x10-2MHI.Whatistheequilibriumconstantforthereactionatthistemperature?

___H2(g)+___I2(g)⇋___HI(g)2.Aquantityof3.88x10-3MNO2isatequilibriumwith1.73x10-4MN2O4at60oC.Whatistheequilibriumconstantforthereaction?

___NO2(g)⇋___N2O4(g)

I

keqecproducti f.CMZ

reactants Aw BTX

I 3 2 2 l Z

keg CHy keg GOICHICHIS GOD cos

4 2 2 3

keg Ector keg CdtHCl 4 027 GHyCHIT

2

keg CHDIata fIEIE I.E

2

Keg NOPEi HI

ChemicalsinliquidsorsolidstatesareNOTincludedintheequilibriumexpressions!!

• Liquidsandsolidshaveafixeddensityandtherefore,afixedconcentration.• Theonlyexceptioniswhentwoliquidsappearinthesameequation,thuseachliquid

dilutestheother.Balanceandwritetheequilibriumexpressionforthefollowingreactions:___Cr2O7-2(aq)+___H2O(l)⇋___H+(aq)+_____CrO42-(aq)

___NaCl(s)⇋___Na+(aq)+___Cl-(aq)

___H2(g)+___Br2(l)⇋___HBr(g)

___B2H6(g)+___O2(g)⇋___B2O3(s)+___H2O(g)

HebdenWorkbook:Pg.60#31,34,35:

2 or more liquids

2 2 XKeq CROFT CH'T Keq Nat 7

to T2 3 X 3

keg CHBI keq CHOPCHI

BzHDfq3

RelativeSizeofKeqRecallthat…

Keq=[products][reactants]

Keq>1 Keq= _________________arefavoured.

Keq<1 Keq= _________________arefavoured.

Whichofthefollowingisleastlikelytofavourtheformationofproducts?

A. 2H2O(g)⇋2H2(g)+O2(g) Keq=7.3x10-18B. N2O(g)+NO2(g)⇋3NO(g) Keq=4.2x10-4C. N2O4(g)⇋2NO2(g) Keq=4.5D. SO2(g)+NO2(g)⇋NO(g)+SO3(g) Keq=85

Explainyouranswertothequestionabove:DoesthevalueofKeqchangewhen…Concentrationchanges?

N2(g)+3H2(g)⇋2NH3(g) ΔH=-92kJ/mol

• Whathappenstotherelativeconcentrationsofeachspecieswhen…o NH3isincreased?

N2(g)+3H2(g)⇋2NH3(g) Keq=

Overall,theconcentration___________staysthesame,soKeq___________________________.

o H2isdecreased?N2(g)+3H2(g)⇋2NH3(g) Keq=

Overall,theconcentration___________staysthesame,soKeq___________________________.

largerafffrtoducts

PRODUCTS

edm

TeamProducts

Cproducts ReactantsREACTANTS Wyarger

amountof

reactants0 aim

BK keg is smallest in a reactantswere favoured the most

q F fd Products TReactants T

ratio staythe same

9 fr f Cproducts dw Creactants d

netdecreaseratio stays the same

changes in C T have theeffect on keg value

Temperaturechanges?

N2(g)+3H2(g)⇋2NH3(g) ΔH=-92kJ/mol

• Whathappenstotherelativeconcentrationsofeachspecieswhen…o Heatisincreased?

N2(g)+3H2(g)⇋2NH3(g)+heat Keq=

Concentrationofreactants__________________.Concentrationofproducts__________________.Therefore,Keqwill__________________.

o Heatisdecreased?N2(g)+3H2(g)⇋2NH3(g)+heat Keq=

Concentrationofreactants__________________.Concentrationofproducts__________________.Therefore,Keqwill__________________.

Forthefollowingequations,statewhethertheKeqwouldincreaseordecrease:Equation: Temperature

change:Keqresult:

G+H⇋J ΔH=-92kJ/mol Increase

A+B+heat⇋ C Increase

P+Q⇋ R+S+150kJ Decrease

W+X+100kJ⇋Y+Z Decrease

N+M⇋P ΔH=+125kJ/mol Increase

r F d r EET Epjdincreasesdecreases

decrease

d d r d ffjf 9decreasesincreases

increasetemperature is the only factor

that has an effect on keg value

keg CPIheat

CRIW

r rd r

d drheat

Forthefollowingequations,determinewhetherthereactionisendothermicorexothermicfromtheobservations:Equation: Temperature

Change:Keq: ExoorEndo:

A+B⇋C+D Increase Increases

E+F⇋ G+H Decrease Decrease

I+J⇋ K+L Increase Decrease

M+N⇋O+P Decrease Increase

Q+R⇋S+T Increase Decrease

Forthefollowingequations,determinewhetherthetemperaturehasincreasedordecreased:Equation: Keqresult: Temperature

change:

G+H⇋J ΔH=-92kJ/mol Increased

A+B+heat⇋ C Decreased

P+Q+150kJ⇋ R+S Increased

W+X+100kJ⇋Y+Z Decreased

N+M⇋P ΔH=+125kJ/mol Increased

endoendoexo

exo

exo

in

PracticeQuestions:1. Balanceandwritetheequilibriumexpressionforeachofthefollowing:

a. _____Fe(s)+_____H+(aq)⇋_____H2(g)+_____Fe2+(aq)

b. _____I-(aq)+_____Cl2(aq)⇋_____I2(s)+_____Cl-(aq)

c. _____CaO(s)+_____CO2(g)⇋_____CaCO3(s)

d. _____CO2(g)⇋_____CO2(aq)

e. _____Na2O(s)⇋_____Na(l)+_____O2(g)

2. A2.0Lflaskcontains0.38molCH4(g),0.59molC2H2(g),and1.4molH2(g)atequilibrium.

Calculatetheequilibriumconstantforthereaction:2CH4(g)⇋C2H2(g)+3H2(g)

X 2keg CE CHz

2 X 2 CH t

keg CFI1 72412X

16 foilkeg CC0

cod

keg Coz

city 0.382 0 0.19M

GHz 0.59 1 0.30M2 OL

CHz t4me O

7oMkeqCHi3f 7 0 Yo 3d I2I

3. Acylindercontains0.12MCoBr2,0.060MCO,and0.080MBr2atequilibrium.Thevolumeofthecylinderissuddenlydoubled.

COBr2(g)⇋CO(g)+Br2(g)a) Whatisthemolarconcentrationofeachgasimmediatelyafterthevolumeofthe

cylinderisdoubled?

b) Explain,intermsofLeChatelier’sprinciple,whythesystemshiftsrighttorestoreequilibrium.

4. Aclosedflaskcontains0.65mol/LN2and0.85mol/LH2atequilibrium.Whatisthe[NH3]?

N2(g)+3H2(g)⇋2NH3(g) Keq=0.017

HebdenWorkbook:Pg.62#36-46

XXconcentration halved

CoBrz 0.060Mco 0.030M

Brd 0.040M

shift right towardside w moreORIGEQ'M to 0040gas molecules

Vol change 0.030 0.040 O020

keg CNHs

Nz Hz3

Solving for NHS

Nlt keg.CNzt.CHi

NHzJ CO0l7 C0.65C0.85T O 082MT