Post on 19-Mar-2016
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KineticsLesson 5
PE Diagrams Mechanisms
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products
Potential Energy
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products
Potential Energy
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products max
Potential Energy high low
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products max
Potential Energy high low Kinetic Energy
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products max
Potential Energy high low Kinetic Energy
high min low
Potential and Kinetic Energy Changes during a CollisionEndothermic Reactants Activated Complex Products max
Potential Energy high low Uphill- endothermic! Kinetic Energy
high min low
Pick the slow and fast reaction
Pick the slow and fast reaction
Ea Ea
Pick the slow and fast reaction
Ea Ea
Slow Fast- low Ea
Reaction Mechanisms Consider the following reaction: 4 HBr(g) + O2(g) → 2H2O(g) + 2Br2(g)
Watch Simulation- set both temperature and mass to the highest setting. Set red to 1 and blue to four and remove the barrier. How often do all five particles collide?
There are five reactant particles.If there are three or more reactant particles they will not likely react in one step.They will react in a series of steps, which is a mechanism.
Mechanism 1 .
HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast
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Reaction Path
Mechanism 1 Cancel out identical formulas to get the overall equation.
HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast
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Reaction Path
Mechanism 1 Cancel out identical formulas to get the overall equation.
HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast
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Reaction Path
Mechanism 1 Cancel out identical formulas to get the overall equation.
HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast
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Reaction Path
Mechanism 1 Intermediates are produced and then consumed and cross out from right (first) and left (second). HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast
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Reaction Path
Mechanism 1 What is left is the overall reaction.
HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast
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Reaction Path
Mechanism 1 What is left is the overall reaction.
HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast 4HBr(g) + O2(g) → 2H2O(g)+ 2Br2(g)
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Reaction Path
Mechanism 1 Step 1, which is the slow step, is called the rate determining step and has the highest activation energy. HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast 4HBr(g) + O2(g) → 2H2O(g)+ 2Br2(g)
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Reaction Path
Mechanism 1 HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast 4HBr(g) + O2(g) → 2H2O(g)+ 2Br2(g)
A potential energy diagram for this reaction might look like this.
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Reaction Path
Mechanism 1 HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast 4HBr(g) + O2(g) → 2H2O(g)+ 2Br2(g)
A potential energy diagram for this reaction might look like this.
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Reaction Path
Mechanism 1
HBr(g) + O2(g) → HOOBr(g) slow HBr(g) + HOOBr(g) → 2HOBr(g) fast 2HOBr(g) +2HBr(g) → 2H2O(g)+ 2Br2(g) fast 4HBr(g) + O2(g) → 2H2O(g)+ 2Br2(g)
highestA potential energy diagram for this Mechanism has three humpsThe slow step has the highest Ea
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Reaction Path
Ea
Ea(rev)
The Rate Determining Step
The slowest step in the reaction mechanism is called the rate-determining step. It has the highest Ea. To increase the rate, you must increase the rate of this step. Increasing the rate of a fast step will not increase the rate of the overall reaction.
Identifying a Catalyst in a Mechanism A catalyst is not consumed in the reaction. It is used in one step; it speeds up the reaction, and then is regenerated in a later step. A catalyst will cancel out but will be on the left side in an earlier step than on the right side.
Identifying a Catalyst in a Mechanism A catalyst is not consumed in the reaction. It is used in one step; it speeds up the reaction, and then is regenerated in a later step. A catalyst will cancel out but will be on the left side in an earlier step than on the right side.
C →→ C
Identifying a Catalyst in a Mechanism A catalyst is not consumed in the reaction. It is used in one step; it speeds up the reaction, and then is regenerated in a later step. A catalyst will cancel out but will be on the left side in an earlier step than on the right side.
C →→ C
Identifying a Catalyst in a Mechanism A catalyst is not consumed in the reaction. It is used in one step; it speeds up the reaction, and then is regenerated in a later step. A catalyst will cancel out but will be on the left side in an earlier step than on the right side.
C →→ C
An intermediate is produced and then consumed. It will be on the right side in an earlier step than on the left side.
Identifying a Catalyst in a Mechanism A catalyst is not consumed in the reaction. It is used in one step; it speeds up the reaction, and then is regenerated in a later step. A catalyst will cancel out but will be on the left side in an earlier step than on the right side.
C →→ C
An intermediate is produced and then consumed. It will be on the right side in an earlier step than on the left side.
→ II →
Identifying a Catalyst in a Mechanism A catalyst is not consumed in the reaction. It is used in one step; it speeds up the reaction, and then is regenerated in a later step. A catalyst will cancel out but will be on the left side in an earlier step than on the right side.
C →→ C
An intermediate is produced and then consumed. It will be on the right side in an earlier step than on the left side.
→ II →
Mechanism 2
1. A + B → C 2. C + D → CD 3. CD + E → ABE + D Overall Equation: Catalyst: Intermediate:
Mechanism 2
1. A + B → C 2. C + D → CD 3. CD + E → ABE + D Overall Equation: Catalyst: Intermediate:
Mechanism 2
1. A + B → C 2. C + D → CD 3. CD + E → ABE + D Overall Equation: Catalyst: Intermediate: C
Mechanism 2
1. A + B → C 2. C + D → CD 3. CD + E → ABE + D Overall Equation: Catalyst: Intermediate: C
Mechanism 2
1. A + B → C 2. C + D → CD 3. CD + E → ABE + D Overall Equation: Catalyst: Intermediate: C CD
Mechanism 2
1. A + B → C 2. C + D → CD 3. CD + E → ABE + D Overall Equation: Catalyst: Intermediate: C CD
Mechanism 2
1. A + B → C 2. C + D → CD 3. CD + E → ABE + D Overall Equation: Catalyst: D Intermediate: C CD
Mechanism 2
1. A + B → C 2. C + D → CD 3. CD + E → ABE + D Overall Equation: A + B + E → ABE Catalyst: D Intermediate: C CD
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Intermediates:
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Reaction Path
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Intermediates:
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Reaction Path
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates:
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Reaction Path
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates: Br Cl
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Reaction Path
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates: Br Cl
ΔH =Ea (forward) = Ea (reverse) =The enthalpy of BrThe enthalpy of BrCl
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Reaction Path
800
200
400
600
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates: Br Cl
ΔH = 200 kJEa (forward) = Ea (reverse) =The enthalpy of Br The enthalpy of BrCl
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Reaction Path
800
200
400
600
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates: Br Cl
ΔH = 200 kJEa (forward) = Ea (reverse) =The enthalpy of Br The enthalpy of BrCl
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Reaction Path
800
200
400
600
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates: Br Cl
ΔH = 200 kJEa (forward) = 600 kJ Ea (reverse) =The enthalpy of Br The enthalpy of BrCl
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Reaction Path
800
200
400
600
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates: Br Cl
ΔH = 200 kJEa (forward) = 600 kJ Ea (reverse) = 400 kJThe enthalpy of Br The enthalpy of BrCl
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Reaction Path
800
200
400
600
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates: Br Cl
ΔH = 200 kJEa (forward) = 600 kJ Ea (reverse) = 400 kJThe enthalpy of Br 300 kJ The enthalpy of BrCl
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Reaction Path
800
200
400
600
Mechanism 3
Step 1 Br2 → 2BrStep 2 Br + OCl2 → BrOCl + ClStep 3 Br + Cl → BrCl
Overall Reaction: Br2 + OCl2 → BrOCl + BrCl Intermediates: Br Cl
ΔH = 200 kJEa (forward) = 600 kJ Ea (reverse) = 400 kJThe enthalpy of Br 300 kJ The enthalpy of BrCl 400 kJ
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Reaction Path
800
200
400
600
Mechanism 4
The following mechanism shows how chlorine-containing fluorocarbons destroy the ozone layer. Ozone is O3 and O 1. CFCl3 → CFCl2 + Cl 2. Cl + O3 → ClO + O2
3. ClO + O → Cl + O2
Overall Reaction: Intermediates:
Mechanism 4
The following mechanism shows how chlorine-containing fluorocarbons destroy the ozone layer. Ozone is O3 and O 1. CFCl3 → CFCl2 + Cl 2. Cl + O3 → ClO + O2
3. ClO + O → Cl + O2
Overall Reaction: Intermediates:
Mechanism 4
The following mechanism shows how chlorine-containing fluorocarbons destroy the ozone layer. Ozone is O3 and O 1. CFCl3 → CFCl2 + Cl 2. Cl + O3 → ClO + O2
3. ClO + O → Cl + O2
Overall Reaction: CFCl3 + O3 + O → CFCl2 + 2O2 + Cl Intermediates:
Mechanism 4
The following mechanism shows how chlorine-containing fluorocarbons destroy the ozone layer. Ozone is O3 and O 1. CFCl3 → CFCl2 + Cl 2. Cl + O3 → ClO + O2
3. ClO + O → Cl + O2
Overall Reaction: CFCl3 + O3 + O → CFCl2 + 2O2+ Cl
Intermediates: Cl ClO
Determine the Missing Step of the Mechanism
Mechanism 5
A + B → C
C + D → B + AD
Overall: A + D + E → ADE
Determine the Missing Step of the Mechanism
Mechanism 5
A + B → C
C + D → B + AD
Overall: A + D + E → ADE
Determine the Missing Step of the Mechanism
Mechanism 5
A + B → C
C + D → B + AD
Overall: A + D + E → ADE
Put in step 3 so that you get the overall reaction
Determine the Missing Step of the Mechanism
Mechanism 5
A + B → C
C + D → B + AD
AD Overall: A + D + E → ADE
Put in AD to cancel
Determine the Missing Step of the Mechanism
Mechanism 5
A + B → C
C + D → B + AD
AD + → Overall: A + D + E → ADE
Put in AD to cancel
Determine the Missing Step of the Mechanism
Mechanism 5
A + B → C
C + D → B + AD
AD + E → Overall: A + D + E → ADE
Put in E
Determine the Missing Step of the Mechanism
Mechanism 5
A + B → C
C + D → B + AD
AD + E → ADE Overall: A + D + E → ADE
Put in ADE
Determine the Missing Step of the Mechanism
Mechanism 6
C + D → CD
CD + E → ABE + D
Overall: A + B + E → ABE
Determine the Missing Step of the Mechanism
Mechanism 6
C + D → CD
CD + E → ABE + D
Overall: A + B + E → ABE
Determine the Missing Step of the Mechanism
Mechanism 6
C + D → CD
CD + E → ABE + D
Overall: A + B + E → ABE
Determine the Missing Step of the Mechanism
Mechanism 6
C + D → CD
CD + E → ABE + D
Overall: A + B + E → ABE
Determine the Missing Step of the Mechanism
Mechanism 6
→ C
C + D → CD
CD + E → ABE + D Overall: A + B + E → ABE
Determine the Missing Step of the Mechanism
Mechanism 6
→ C
C + D → CD
CD + E → ABE + D Overall: A + B + E → ABE
Determine the Missing Step of the Mechanism
Mechanism 6
A + B → C
C + D → CD
CD + E → ABE + D Overall: A + B + E → ABE
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
Cl
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
Cl
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
Cl + O3
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
Cl + O3 → ClO + O2
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
Cl + O3 → ClO + O2
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
Cl + O3 → ClO + O2
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
Cl + O3 → ClO + O2
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl
Determine the Missing Step of the Mechanism
Mechanism 7
CFCl3 → CFCl2 + Cl
Cl + O3 → ClO + O2
ClO + O → Cl + O2
Overall: O + CFCl3 + O3 → CFCl2 + 2O2 + Cl