Approaching

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Approaching Equilibrium Lesson 1
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Approaching Equilibrium   Many chemical reactions
are reversible if the activation energy is low
and the system is closed. Reactants ?
Products  
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Approaching Equilibrium Many chemical reactions
are reversible if the activation energy is
low.   Reactants ? Products  
Forward Reaction is left to right
 
Reverse Reaction is right to left
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Lets see what happens to some reactants if they
are placed in a reaction vessel and allowed to
react.  
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Approaching Equilibrium
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium
Products
Reactants
Forward Rate
Reverse Rate
Are Equal
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Approaching Equilibrium
Products
Reactants
Forward Rate
Reverse Rate
Are Equal
Are Constant
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Graphing the Approach to Equilibrium
 
product
 Concentration
reactant
Time
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Graphing the Approach to Equilibrium
 
reactant
 Concentration
product
Time
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Graphing the Approach to Equilibrium
 
Forward rate
 Concentration
Reverse rate
Overall rate
Time
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Approaching Equilibrium Reactant concentrations
start high and decrease as the reaction proceeds.
The forward rate, which depends on collisions of
the reactants, also decreases.   Product
concentrations start at zero and increase as the
reaction proceeds. The reverse rate, which
depends on collisions of the products, also
increases.   Eventually the forward rate is
equal to the reverse rate and the concentrations
are constant. This is equilibrium.
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Characteristics of a System at Equilibrium   The
Forward rate The Reverse rate   The Reactant
and Product concentrations are constant   The
Macroscopic (observable) properties are
constant   The system is Dynamic as the forward
and reverse reactions continue.   The equilibrium
can be approached from starting with reactants or
starting with products.
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Approaching Equilibrium from Products
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium from Products
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium from Products
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium from Products
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium from Products
Products
Reactants
Forward Rate
Reverse Rate
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Approaching Equilibrium from Products
Products
Reactants
Forward Rate
Reverse Rate
Are Equal
Are Constant Same as before
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If you start with products all aspects of the
approach to equilibrium are reversed
Products and Reverse Rate decrease
Reactants and Forward Rate increases
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Conditions Necessary for Equilibrium
Closed system
Constant temperature
Ea is low so the reaction is reversible