Drill:

1
Drill

• List five factors explain how each affect
  reaction rates

2
Review DrillCheck HW
3
CHM II HW

• Review PP-19 20
• Complete the attached worksheet turn it in
  tomorrow
• Lab Thursday

4
Are there any questions on previous material?
5
Chemical Equilibria
6
Equilibrium

• The point at which the rate of a forward reaction
  the rate of its reverse reaction

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Equilibrium

• The concentration of all reactants products
  become constant at equilibrium

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Equilibrium

• Because concentrations become constant,
  equilibrium is sometimes called steady state

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Equilibrium

• Reactions do not stop at equilibrium, forward
  reverse reaction rates become equal

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11
Reaction

• aA(aq) bB(aq) pP(aq) qQ(aq)
• Ratef kfAaBb
• Rater krPpQq
• At equilibrium, Ratef Rater
• kfAaBb krPpQq

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At equilibrium, Ratef Rater kfAaBb
krPpQq kf /kr (PpQq)/ ( AaBb) kf
/kr Kc Keq in terms of concentration Kc
(PpQq)/ ( AaBb)
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All Aqueous aA bB pP qQ
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15
Equilibrium Expression
( Products)p (Reactants)r
Keq
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Drill Solve Rate Expr
X Y M N fast 3M N 2G
fast 2N K fast 2G K
Prod. slow
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Drill Solve Rate Expr
X Y M N fast 3M N 2G
fast 2N K fast 2G K
Prod. slow
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Work from the slow step up
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Drill Solve Rate Expr
X Y M N fast 3M N 2G
fast 2N K fast 2G K
Prod. slow
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1) Cancel K G
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Drill Solve Rate Expr
X Y M N fast 3M N 2G
fast 2N K fast 2G K
Prod. slow
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1. Cancel K GTriple rxn 1 cancel

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Drill Solve Rate Expr
3X 3Y 3M 3N 3M N 2G
fast 2N K fast 2G K
Prod. slow
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Solve Rate Law
A B C D fast 4 C A
2G fast 2 K 4D B fast G K
2 Q 2 W fast Q W Prod. slow
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Drill Solve Rate Law
A B C D fast 4 C A
2G fast 2 K 4D B fast G K
2 Q 2 W fast Q W Prod. slow
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1) Reverse step 3
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Drill Solve Rate Law
A B C D fast 4 C A
2G fast 4 D B 2K fast G K
2 Q 2 W fast Q W Prod. slow
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1. Reverse Rxn 3Divide Rxn 4 by 2 cancel

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Drill Solve Rate Law
A B C D fast 4 C A
2G fast 4 D B 2K fast G/2 K/2
Q W fast Q W Prod. slow
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1. Reverse Rxn 3Divide Rxn 4 by 2 cancelDivide
   Rxns 2 3 by 4 cancel

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Drill Solve Rate Law
A B C D fast C A/4
G/2 fast D B/4 K/2 fast G/2 K/2
Q W fast Q W Prod. slow
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1. Reverse Rxn 3Divide Rxn 4 by 2 cancelDivide
   Rxns 2 3 by 4 cancelAdd the rxns

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5/4 A 5/4 B ? ProductRate kA5/4B5/4
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Review Collect Drill HW
35
CHM II HW

• Review PP-19 20
• Remember M. S.

36
Are there any questions on previous material?
37
Equilibrium Applications

• When K gt1, P gt R
• When K lt1, P lt R

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Equilibrium Calculations

• Kp Kc(RT)Dngas

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Equilibrium Expression

• Reactants or products not in the same phase are
  not included in the equilibrium expression

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Equilibrium Expression
aA(s) bB(aq)?? cC(aq) dD(aq)
Cc Dd Bb
Keq
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Reaction Mechanism

• When one of the intermediates anywhere in a
  reaction mechanism is altered, all intermediates
  are affected

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Reaction Mechanism

• 1) A B lt---gt C D
• 2) C D lt---gt E K
• 3) E K lt---gt H M
• 4) H M lt----gt P

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Lab Results

• 100 80 60 40
• RT 5.21 8.42 11.9 21.7
• WR 2.75 4.23 7.96 11.2

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ReactionQuotient
aA(aq) bB(aq) ?? pP(aq) qQ(aq)
where A, B, P, and Q are molarities at
any time. Q K only at equilibrium.
45
Drill NH3 H2 N2

• At a certain temperature at equilibrium Pammonia
  4.0 Atm, Phydrogen 2.0 Atm, Pnitrogen 5.0
  Atm.
• Calculate Keq

46
Review Collect Drill HW
47
CHM II HW

• Review PP 19 20
• Complete the attached assignment turn it in
  tomorrow

48
Are there any questions on previous material?
49
ReactionQuotient
aA(aq) bB(aq) ?? pP(aq) qQ(aq)
where A, B, P, and Q are molarities at
any time. Q K only at equilibrium.
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Equilibrium Applications

• When K gt Q, the reaction goes forward
• When K lt Q, the reaction goes in reverse

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Equilibrium Calculations

• aA bB ?? pP qQ
• Stoichiometry is used to calculate the
  theoretical yield in a one directional rxn

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Equilibrium Calculations

• aA bB ?? pP qQ
• In equilibrium rxns, no reactant gets used up
  so, calculations are different

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Equilibrium Calculations

• Set balance rxn
• Assign amounts with x
• Write eq expression
• Substitute amounts
• Solve for x

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Equilibrium Calculations

• CO H2O CO2 H2
• Calculate the partial pressure of each portion at
  eq.when 100.0 kPa CO 50.0 kPa H2O are combined
  
• Kp 3.4 x 10-2

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Equilibrium Calculations
CO H2O CO2 H2 100 -x 50 - x x
x PCO2PH2 x2
PCOPH2O (100-x) (50-x) Kp 3.4 x 10-2

KP
Send to the next page
56
Equilibrium Calculations
x2 (100 -x)(50 - x)
x2 5000 -150x x2 x2 170 - 5.1x
0.034x2 0.966x2 5.1x - 170 0

3.4 x 10-2
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Equilibrium Calculations
0.966x2 5.1x - 170 0 Use the quadratic
equation to solve for x x 11 x
-16 Substitute 11 back into the originally
assigned
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Equilibrium Calculations
CO H2O CO2 H2 100 -x 50 - x x
x 100-11 50-11 11 11 PCO 89 kPa
PH2O 39 kPa PCO2 11 kPa PH2 11 kPa
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Equilibrium Calculations
Xe (g) F2(g) XeF2(g) Calculate the
partial pressure of each portion when 50.0 kPa Xe
100.0 kPa F2 are combined Kp 4.0 x 10-1
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Equilibrium Calculations
Xe F2 XeF2 50 -x 100 - x x
PXeF2 x PXePF2
(50-x) (100-x) Kp 4.0 x 10-1

KP
Send to the next page
61
Equilibrium Calculations
x (50 -x)(100 - x) x 5000
-150x x2 x 2000 - 60x 0.40x2 0.40x2 -61x
2000 0

4.0 x 10-1
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Equilibrium Calculations
0.40x2 - 61x 2000 0 Use the quadratic
equation to solve for x x 48 x
105 Substitute 48 back into the original
assignmented
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Equilibrium Calculations
Xe F2 XeF2 50 -x 100 - x x
50-48 100-48 48 PXe 2 kPa PF2
52 kPa PXeF2 48 kPa
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SO2 O2 SO3

• Determine the magnitude of the equilibrium
  constant if the partial pressure of each gas is
  0.667 Atm.

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Drill Write the equilibrium expression solve
its magnitude when PNO2 PN2O4 50 kPa each at
eq
N2O4(g) NO2(g)
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Review DrillCheck HW
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CHM II HW

• Review PP-20
• Complete the attached HW

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CHM II Schedule

• Lab Later this week
• Test Early next week

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Are there any questions on previous material?
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Equilibrium Calculations
Xe (g) 2 F2(g) XeF4(g) Calculate the
partial pressure of each portion when 75 kPa Xe
20.0 kPa F2 are combined Kp 4.0 x 10-8
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Le Chateliers Principle

• If stress is applied to a system at equilibrium,
  the system will readjust to eliminate the stress

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LC Eq Effects

• A(aq) 2 B(aq) lt---gt
• C(aq) D(aq) heat
• Write equilibrium exp
• What happens if

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LC Eq Effects

• 2 A(aq) B(s) lt---gt
• C(aq) 2 D(aq) heat
• Write equilibrium exp What happens if

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LC Eq Effects

• 2 A(g) 2 B(g) lt---gt
• 3 C(g) 2 D(l)
• What happens if

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Equilibrium Applications

• DG DH - TDS
• DG - RTlnKeq

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Drill Solve for K
A(aq) 2 B(aq) C(s) 2 D(aq) Calculate
Keq if A 0.30 M B 0.20 M C
5.0 g D 0.30 M
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Review Collect Drill HW
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Schedule

• Lab Friday
• Test Next week

79
CHM II HW

• Review PP-20
• Complete the attached assignment turn it in
  tomorrow.

80
Are there any questions on previous material?
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A(aq) B(aq) AB(aq) Calculate the
equilibrium concentration of each species when
equal volumes of 0.40 M A 0.20 M B are
combined. Keq 0.50
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Equilibrium Calculations
Xe (g) F2(g) XeF2(g) Calculate the
partial pressure of each portion when 80.0 kPa
Xe 60.0 kPa F2 are combined Kp 4.0 x 10-2
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Drill
A B C D Calculate the
equilibrium concentration of each species when
equal volumes of 0.60 M A 0.80 M B are
combined. Keq 5.0 x 10-6
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Review Collect Drill HW
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CHM II HW

• Review PPs 19 20
• Review both for the Test on Monday.

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The Test on Rxn Rates Chemical Equilibria will
be on Monday
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Are there any questions on previous material?
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Working with Equilibrium Constants
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When adding Reactions

• Multiply Ks

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• A B K1
• B C K2
• A C K3
• K3 (K1)(K2)

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Solve K for each
K1

• A B C D
• C D P Q
• A B P Q

K2
K3
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When doubling Reactions
Square Ks
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A B K1 2 A 2 B K2 K2 (K1)2
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When a rxn is multiplied by any factor, that
factor becomes the exponent of K
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A B K1 1/3 A 1/3 B K2 K2 (K1)1/3
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When reversing Reactions
Take 1/Ks
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A B K1 B A K2 K2 1/K1
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Equilibrium Calculations
CuCl6-4 (aq) 2 NH3(aq)
Cu(NH3)2Cl4-2(aq) Calculate the molarity of
each portion when 0.10 M CuCl6-4 1.0 M NH3 are
combined Kformation 0.060
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Equilibrium Calculations
Rn(g) F2(g) RnF2(g) Calculate the
partial pressure of each portion when 25 kPa Rn
75 kPa F2 are combined Kp 4.0 x 10-2
100
Drill
A B P Q Calculate the concentration
of each portion at equilibrium when 100.0 mL 0.50
M A is added to 150 mL 0.50 M B Kc 6.0 x 10-8
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Review DrillCheck HW
102
Next Test

• Monday

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Reviewfor theTest
104
Rate Law aA bB pP qQ
Rate
kAaBb
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Equilibrium Equation aA bB pP qQ
PpQq AaBb
Kc
at equilibrium
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Reaction Quotient aA bB pP qQ
PpQq AaBb
Q
at the other conditions
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The data on the next slide was obtained in lab.
Use that data to solve for the order with
respect to each reactant, the reaction order, the
rate expression, k, Ea.
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Experimental Results

• Exp A B Rate
• 127 1.0 1.0 2.0 x 10-2
• 227 2.0 1.0 4.0 x 10-2
• 327 1.0 2.0 8.0 x 10-2
• 477 1.0 1.0 2.0

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Reaction Mechanism

• Step 1 A lt--gt B fast
• Step 2 2 B lt--gt 3C fast
• Step 3 C lt--gt 2D fast
• Step 4 D ? P slow

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LC Eq Effects

• 2 A(aq) B(s) lt---gt
• C(aq) 2 D(aq) heat
• Write equilibrium exp What happens if

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LC Eq Effects

• 3 A(g) B(g) lt---gt
• 2 C(g) 2 D(l)
• Write equilibrium exp
• What happens if

112
SO O2 SO3Calculate the equilibrium
pressures if SO at 80.0 kPa is combined with O2
at 40.0 kPa. K 2.00
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Equilibrium Calculations
I2 2 S2O3-2 S4O6-2 2 I- Calculate the
equilibrium concentration of each portion when
its 0.25 M I2 0.50 M S2O3-2 at the start of
the rxn. Kc 4.0 x 10-8
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Clausius-Claperon Eq
(T2)(T1) k2 (T2 T1) k1
Ea R ln
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Clausius-Claperon Eq
(T2)(T1) P2 (T2 T1) P1
Hv R ln
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Clausius-Claperon Eq
(T2)(T1) K2 (T2 T1) K1
DH R ln
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DG DH - TDSDGo -RTlnK
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Experimental Results

• Exp A B C time
• 1 1.0 1.0 1.0 16
• 2 2.0 1.0 1.0 2
• 3 1.0 2.0 1.0 8
• 4 1.0 1.0 2.0 4

119
Drill
1 A 1 B 1 Z 1 Y Calculate the
concentration of each portion at equilibrium when
1.0 L 0.50 M A is added to 1.5 L 0.50 M B Kc
2.0 x 10-2
120
Drill

• Calculate the heat of reaction when K
• 2.5 x 10-6 at 27oC,
• K 2.5 x 10-4 at 127oC.

121
Write the Eq Expression
AB(aq) A(aq) B(aq) Calculate A,
B, AB at equilibrium when AB 0.60 M at
the start Keq 6.0 x 10-5
122
Write the Eq Expression
PQ(aq) P(aq) Q(aq) Calculate P,
Q, PQ at equilibrium when PQ 0.90 M at
the start Keq 9.0 x 10-5
123
Write the Eq Expression
AB(aq) A(aq) B(aq) Calculate A,
B, AB at equilibrium when AB 0.60 M at
the start Keq 6.0 x 10-5
124
Experimental Results

• Exp A B C Rate
• 1 0.1 0.1 0.2 2
• 2 0.1 0.3 0.2 18
• 3 0.1 0.1 0.8 8
• 4 0.2 0.1 0.2 64

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• A B lt---gt C D
• C H lt---gt M N
• N T lt---gt P Q
• What happens all intermediates if

126
1A 1B 1P 1QAi 0.20 M Calcu-Bi 0.30
M late thePi 0.20 M eq con-Qi 0.30
M centra-Kc 0.020 tion of ea.