Energy Diagrams: Drawing it Out

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Energy Diagrams Drawing it Out
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Why are we learning this?

• Energy diagrams show how a reaction works.
• Energy diagrams display
• The energy of reactants and products
• The energy needed for a reaction to occur
• The energy absorbed or released due to reaction

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Energy Diagram Parts

• Potential Energy of the reactants
• Potential Energy of the products
• Activation Energy E the amount of energy
  required to reach the transition state or
  activated complex from the reactant
• Transition State, Ts (Activated Complex) when
  bonds break and form and reactants become
  products
• Enthalpy, DH science word for heat, Energy of
  products energy of reactants

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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products            
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products            
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products              
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products              
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products         Potential
Energy      
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products         Potential
Energy      
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products         max Potential
Energy high    low    
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products         max Potential
Energy high    low     Kinetic
Energy
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products         max Potential
Energy high    low     Kinetic
Energy high min low
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Potential and Kinetic Energy Changes during a
Collision Endothermic    Reactants Activated
Complex Products         max Potential
Energy high    low   Uphill-
endothermic!   Kinetic Energy high
min low
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Putting Pieces Together

• Transition State, Ts

Activation Energy of forward reaction, EF EF Ts
- Reactants
Reactants
Enthalpy of forward reaction, DHF
Products
DHF Products - Reactants
Energy
Reaction
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Putting Pieces Together

• Transition State, Ts

Activation Energy of reverse reaction, ER ER Ts
- Products
Reactants
Enthalpy of forward reaction, DHR
Products
DHR Reactants - Products
Energy
Reaction
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Types of Energy Diagrams

• Endothermic the reaction absorbs heat so DH is
  positive
• The reactants have less potential energy than the
  products

A - - - B
AB
DH gt 0
A B
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Types of Energy Diagrams

• Exothermic the reaction releases heat so DH is
  negative
• The reactants have more potential energy than the
  products

A - - - B
A B
DH lt 0
AB
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Types of Energy Diagrams

• Catalysts lower the activation energy of a
  reaction by finding an alternate route. However,
  the change in heat, or enthalpy is the same.

Blue without Catalyst Green with Catalyst
A - - - B
A B
DH lt 0
AB
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Try it together
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Use the numbers to find What is EF? What is
DHF? What is DHR? What is ER?
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150
100
50
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Pick the slow and fast reaction
Slow
Fast- low Ea