Equilibrium 1
Dynamic Equilibrium (7.1.1)
Reference: Higher Level Chemistry, p. 238-240
1
Assessment Statements
7.1.1
Outline the characteristics of chemical and
physical systems in a state of equilibrium.
2
Chemical
A Equilibrium
Chemical Equilibrium
- Some Examples
In the Environmental Chemistry unit, you looked at
this example of an equilibrium system:
3O2(g) ⇌ 2O3(g)
What does “equilibrium” mean in this context?
What is required for an “equilibrium” to exist?
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Chemical Equilibrium - Some Examples
+
HHb
+ O2 ⇌ HbO2 +
+
H
N2 + 3H2 ⇌ 2NH3
homeostasis - many mechanisms
4
Chemical
Chemical Equilibrium
Equilibrium -- Some
A Simple
Examples
Look
https://www.youtube.com/watch?v=dUMmoPdwBy4
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Chemical
ChemicalEquilibrium
Equilibrium--Some
Requirements
Examples
1. a reversible reaction
dissolving and
precipitating salts
phase changes
synthesis and
decomposition of ionic
compounds
acid-base indicators
thermochromic
products
6
Chemical
ChemicalEquilibrium
Equilibrium--Some
Requirements
Examples
2. a closed system
X
√
reactions involving gases
must be in sealed
containers
︀︁︂︃︄︅︆︇︈︉︊︋︌︍︎️
aqueous reactions
(no gases) may be in
open containers
the Earth may be considered
as a closed system
7
Chemical
Chemical Equilibrium
Equilibrium -- Some
Characteristics
Examples
1. rate of forward reaction = rate of reverse reaction
equilibrium state
rate
forward reaction
reverse reaction
time
8
Chemical
Chemical Equilibrium
Equilibrium -- Some
Characteristics
Examples
2a. macroscopic properties are constant
constant colour
constant pressure
constant pH
constant volume
constant conductivity
time
concentration
concentration
concentration
2b. reactant and product concentrations are constant,
but not necessarily equal
time
time
9
Chemical
Chemical Equilibrium
Equilibrium -- Some
Characteristics
Examples
3. the system is DYNAMIC
At the microscopic (or molecular) level, changes are still occurring.
Reactants are being converted to products AND
products are being converted back to reactants.
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Chemical
Chemical Equilibrium
Equilibrium -- Some
Characteristics
Examples
4. equilibrium can be approached from either direction
reactants ⇌ products
starting with products
concentration
concentration
starting with reactants
time
time
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Chemical
Chemical
Equilibrium
Equilibrium
- Some
- Act Examples
It Out!
Pl(wad) ⇌ Pr(wad)
2 teams, 64 wads of paper
Scenario 1:
Equal size teams, all wads starting on left side
time (s)
# wads
(left)
# wads
(right)
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Chemical
Chemical
Equilibrium
Equilibrium
- Some
- Act Examples
It Out!
Scenario 2:
left side = ___ students; right side = ___ students; all wads on right side
time (s)
# wads
(left)
# wads
(right)
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Chemical
Chemical
Equilibrium
Equilibrium
- Some
- Act Examples
It Out!
Scenario 3:
left side = ___ students; right side = ___ students; all wads on right side
time (s)
# wads
(left)
# wads
(right)
14
Chemical
Chemical
Equilibrium
Equilibrium
- Some
- Act Examples
It Out!
How does this simulation demonstrate the requirements and characteristics
of a chemical equilibrium?
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