5 - 1chemistry for allied health: equilibrium chapter 9 chemical equilibrium rates of reaction...
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5 - 1Chemistry for Allied Health: Equilibrium
CHAPTER 9CHAPTER 9Chemical EquilibriumChemical Equilibrium
Rates of ReactionRates of Reaction
EquilibriumEquilibrium
5 - 2Chemistry for Allied Health: Equilibrium
En
erg
y
Rxn Progress
2H2(g) + O2(g) 2H2O + Energy2H2(g) + O2(g) 2H2O + Energy
Just because something has the potential to reactJust because something has the potential to react doesn’t mean it will do so immediately.doesn’t mean it will do so immediately.Just because something has the potential to reactJust because something has the potential to react doesn’t mean it will do so immediately.doesn’t mean it will do so immediately.
HH2(g)2(g) + OO2(g)2(g) may may
stay together for stay together for
lifetime without lifetime without
reacting to form reacting to form
water.water.
HH2(g)2(g) + OO2(g)2(g) may may
stay together for stay together for
lifetime without lifetime without
reacting to form reacting to form
water.water.
Reaction RatesReaction Rates
Very stableproduct(H < 0)HH
5 - 3Chemistry for Allied Health: Equilibrium
Chemical kineticsChemical kineticsThe study of reaction rates (speed)The study of reaction rates (speed)
EnthalpyEnthalpy Only tell us if a reaction willwill && occur but not not how long it
will EntropyEntropy take.
KineticsKinetics Measures the time requiredtime required for a reaction to occur.
5 - 4Chemistry for Allied Health: Equilibrium
Chemical kineticsChemical kinetics
Kinetics of a chemical reaction can tell us -
how longhow long it will take for a reaction to reach completion.
how chemicals react to form products (mechanism(mechanism).
effects of catalystscatalysts and enzymes.
how to controlhow to control a reaction.
5 - 5Chemistry for Allied Health: Equilibrium
Speed at which reactant is used up.Speed at which product forms.
Oxidation: Paper burningburning Oxidation: Paper burningburning
Paper turning Paper turning yellowyellowPaper turning Paper turning yellowyellow
Oxidation: Nails rustingrustingOxidation: Nails rustingrusting
Reaction RatesReaction Rates
Fast:Fast:
Slow:Slow:
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Figure 9.1Figure 9.1
Reaction RatesReaction RatesFast:Fast:
Slow:Slow:
Slower:Slower:
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A reaction won’t happen if:A reaction won’t happen if:
Effective collisionsEffective collisions
Molecules are not alignedaligned correctly.
Insufficient energy to break bondsenergy to break bonds. N2 O2 N2 O2
5 - 8Chemistry for Allied Health: Equilibrium
3. They have to have enough E.
For reactants to make products:For reactants to make products:1. Molecules must collidecollide
(solvents really help)(solvents really help)
2. They have to be alignedaligned correctly.
(Parked cars don’t collide)(Parked cars don’t collide)
Effective collisionsEffective collisions
5 - 9Chemistry for Allied Health: Equilibrium
Activation EnergyActivation EnergyThe activation energyactivation energy Eact
Is the minimum energy needed for a reaction to take place upon proper collision of reactants.
5 - 10Chemistry for Allied Health: Equilibrium
Show the E duringa reaction.
Show the E duringa reaction.
Energy diagramsEnergy diagrams
HH
Activation energy
EEactact
En
erg
yA temporary state where bonds arereforming. Activated
Complex
ActivatedComplex
5 - 11Chemistry for Allied Health: Equilibrium
Factors Influencing Rxn RatesFactors Influencing Rxn RatesReaction rates can be affected by :Reaction rates can be affected by :
1. Reactant structure(polar vs. nonpolarpolar vs. nonpolar)• physical state of reactants
(vapor vs liqvapor vs liq.)2.2. ConcentrationConcentration of reactants
(medicationsmedications)• surface areasurface area (sugar cube vs crystalssugar cube vs crystals)
3.3. TemperatureTemperature (hypothermia & metabolismhypothermia & metabolism)
4.4. CatalystCatalyst (HH22OO22 & blood & blood)
5 - 12Chemistry for Allied Health: Equilibrium
IfIncrease reactant reactant
concentrationconcentrationthenthen
Increase # of collisions# of collisionsso so
Increase reaction ratereaction rate.
Reaction RatesReaction Rates
Concentration :Concentration :1.1. More Reactants:More Reactants:
More cars More cars More collisions More collisions
5 - 13Chemistry for Allied Health: Equilibrium
Reaction RatesReaction Rates
Concentration:Concentration:1.1. More Reactants:More Reactants:
8 blocks:8 blocks:34 surfaces34 surfaces
8 blocks:8 blocks:24 surfaces24 surfaces
More surface area More surface area More collisions More collisions
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Reaction RatesReaction Rates
Temperature:Temperature:2.2. Higher Temperature:Higher Temperature:
Faster cars Faster cars More collisions More collisions
More Energy More Energy More collisions More collisions
Reacting molecules move faster,
providing colliding molecules w/ Eact.
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Reaction RatesReaction Rates
Catalyst:Catalyst:3.3. Adding a Catalyst:Adding a Catalyst:
Lower ELower Eactact More collisions More collisions
Uncatalysed reactionUncatalysed reaction
5 - 16Chemistry for Allied Health: Equilibrium
Reaction RatesReaction Rates
Catalyst:Catalyst:3.3. Adding a Catalyst:Adding a Catalyst:
Lower ELower Eactact More collisions More collisions
Uncatalysed reactionUncatalysed reaction
Catalysed reactionCatalysed reaction
Lower activation energy
Alters reaction mechanism but not productsAlters reaction mechanism but not productsIs not used up during the reaction.Is not used up during the reaction.
5 - 17Chemistry for Allied Health: Equilibrium
Reaction RatesReaction Rates
Catalyst:Catalyst:3.3. Adding a Catalyst:Adding a Catalyst:
Lower ELower Eactact More collisions More collisions
Uncatalysed reactionUncatalysed reaction
Catalysed reactionCatalysed reaction
Lower activation energy
EnzymesEnzymes are biological catalysts.EnzymesEnzymes are biological catalysts.
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Catalytic ConverterCatalytic Converter
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Catalytic ConverterCatalytic Converter
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EquilibriumEquilibriumA state where the forward and reverse
conditions occur at the same rate.
DynamicEquilibrium
I’m in staticequilibrium.
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Chemical equilibriumChemical equilibriumDynamic processDynamic process Rate of forward Rxn = Rate of reverse RxnRate of forward Rxn = Rate of reverse Rxn
HH22OO(l) (l) HH22OO((g)g)
(reactant) (product)(reactant) (product)
DynamicEquilibriumConcentration of reactants Concentration of reactants
and products remain constantand products remain constant over time.over time.
5 - 26Chemistry for Allied Health: Equilibrium
Equilibrium andEquilibrium andreaction ratesreaction rates
A point is ultimatelyreached where therates of the forwardrates of the forwardand reverse reactionsand reverse reactionsare the same.are the same.
At this point, equilibrium is achieved.
Rea
ctio
n r
ate
Time
HH22OO(l)(l) H H22OO(g)(g)
(reactant) (product)(reactant) (product)
5 - 27Chemistry for Allied Health: Equilibrium
Figure 9.8Figure 9.8
2SO2(g) + O2(g) 2SO3(g)
At Equilibium
SO2(g)+O2(g)
Initially
SO3(g)
Initially
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Figure 9.9Figure 9.9
2SO2(g) + O2(g) 2SO3(g)
At Equilibium
SO2(g)+O2(g)
Initially
SO3(g)
Initially
5 - 29Chemistry for Allied Health: Equilibrium
Figure 9.10Figure 9.10
N2(g) + O2(g) 2NO(g)
At Equilibium
N2(g)+O2(g)
Initially
NO(g)
Initially
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EquilibriumEquilibriumC
on
cen
trat
ion
Time
Kinetic EquilibriumRegion Region
CConcentration of oncentration of reactants and products reactants and products remain constantremain constant over time. over time.
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[C]c [D]d
[A]a [B]bKeq =
Equilibrium constant (K)Equilibrium constant (K)
Equilibrium expressionEquilibrium expression (for any reaction at constant
temperature)aA + bB cC + dD
moles per litermoles per liter
coefficients
productsreactants
5 - 32Chemistry for Allied Health: Equilibrium
Figure 9.11Figure 9.11
[C]c [D]d
[A]a [B]bKeq =
aA + bB cC + dDproductsreactants
Equilibrium constant (K)Equilibrium constant (K)
5 - 33Chemistry for Allied Health: Equilibrium
N2(g) + 3 H2(g) 2 NH3(g)
Keq = [ NH3 ] 2
[ N2 ] [ H2 ] 3
Equilibrium constant (K)Equilibrium constant (K)
5 - 34Chemistry for Allied Health: Equilibrium
Le Chatelier’s principleLe Chatelier’s principle
Stress causesStress causes shift shift in equilibriumin equilibrium
Adding or removing reagent
N2(g) + 3 H2(g) 2 NH3(g)
Stress causesStress causes shift shift in equilibriumin equilibrium
Adding or removing reagent
N2(g) + 3 H2(g) 2 NH3(g)
Add moreN2?
NN22
Reaction shifts to the right[NH3] inc, [H2] dec
5 - 35Chemistry for Allied Health: Equilibrium
Le Chatelier’s principleLe Chatelier’s principle
Adding or removing reagent
N2(g) + 3 H2(g) 2 NH3(g)
Adding or removing reagent
N2(g) + 3 H2(g) 2 NH3(g)
Add moreNH3?
NHNH33
Reaction shifts to the left[NN22] and [H2] inc
5 - 36Chemistry for Allied Health: Equilibrium
Le Chatelier’s principleLe Chatelier’s principle
Adding Pressure affects an equilibrium with gases
N2(g) + 3 H2(g) 2 NH3(g)
Add PP?
Increasing pressure causes the equilibrium to shift to the side with the least moles of gas.
4 mol
of reactants
2 molof products
5 - 37Chemistry for Allied Health: Equilibrium
Le Chatelier’s principleLe Chatelier’s principle
Temperature can also have an effect.
For exothermicexothermic reactions
reactants products + heatreactants products + heat
Raising the temperature shifts it to the left.
For endothermicendothermic reactions
heat + reactants productsheat + reactants products
Raising the temperature shifts it to the right.
5 - 39Chemistry for Allied Health: Equilibrium
FeClFeCl33 + 3NH+ 3NH44CNSCNS Fe(CNS)Fe(CNS)33 + + 3NH3NH44ClClYellowYellow RedRed
1. What happens when FeClFeCl33 is added ?2. What happens when NHNH44CNS CNS is added ?3. What happens when Fe(CNS)Fe(CNS)33 is removed ?
Le Chatelier’s principleLe Chatelier’s principle
5 - 40Chemistry for Allied Health: Equilibrium
Figure 9.12Figure 9.12
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Figure 9.13Figure 9.13
5 - 42Chemistry for Allied Health: Equilibrium
ExampleExampleOO22 transport in blood transport in blood
Equilibrium equationEquilibrium equation
HbHb + 4 OO22 Hb(OHb(O22))44
lungs = abundance of Oabundance of O22 :lungs = abundance of Oabundance of O22 :
IncInc
Cells = lack of Olack of O22 :Cells = lack of Olack of O22 :
DecDec
5 - 43Chemistry for Allied Health: Equilibrium
ExampleExampleOO22 transport in blood transport in blood
Equilibrium equationEquilibrium equation
HbHb + 4 OO22 Hb(OHb(O22))44
Equilibrium expressionEquilibrium expression
KKHbHb = = [Hb(O[Hb(O22))44]]
[Hb][Hb] [O[O22]]44
5 - 44Chemistry for Allied Health: Equilibrium
lungslungs = = abundance of Oabundance of O22 : :
ExampleExampleOO22 transport in blood transport in blood
HbHb + 4 + 4 OO22 Hb(OHb(O22))44
HbHb + 4+ 4 OO22 Hb(OHb(O22))44
Cells =Cells = lack of Olack of O22 : :
Oxygen is given up by the hemoglobinOxygen is given up by the hemoglobin..
OxygenOxygen is picked up by the is picked up by the hemoglobin.hemoglobin.
(Hypoxia) :(Hypoxia) :
50% more 50% more red blood cellsred blood cells in persons in persons living at high altidudes.living at high altidudes.