EQUILIBRIUM
Equilibrium
● System is at equilibrium when rate of forward reaction is equal to the
rate of backward reaction
● Concentrations of reactants + products remain unchanged at
equilibrium
● Reversible reaction = products can reform to produce reactants
● Only occurs in a closed system (only energy but not matter can be
exchanged)
Dynamic equilibrium
● Rate of forward + backward reaction is equal
● No changes at macroscopic level
● Changes in microscopic level
Equilibrium state
1. Dynamic: Reaction hasn't stopped, forwards + backwards reaction
occur at same rate
2. Closed system: No exchange of matter, reactants + products can
recombine
3. Constant concentration of reactants/products: Produced + destroyed
at an equal rate
, 4. No macroscopic changes: Because they depend on concentration of
reactants and products
5. Equilibrium can be reached from either direction
Equilibrium constant (Kc)
● Kc = [Products]^Coefficient stoichiometry/ [Reactants]^Coefficient
stoichiometry
● Kc has a fixed value at a specific temperature
Magnitude of Kc
● Kc > 1 = More products
- [Products] > [Reactants]
● Kc < 1 = More reactants
- [Reactants] > [Products]
● Kc = 1
- [Products] = [Reactants]
- Half-point has been reached
Reaction quotient (Q)
● Q = Equilibrium expression with non-equilibrium concentration of
[Products] and [Reactants]
● Can be used to measure whether reaction is at equilibrium
- Q = Kc → Equilibrium
- Q > Kc → Q decreases as the reaction moves toward equilibrium →
[Reactants] should increase, [Products] should decrease → Reaction
shifts to the left
● Q < Kc → Q increases as the reaction moves towards equilibrium →
[Reactants] should decrease, [Products] should increase → Reaction
shifts to the right
Kc relationships with different reactions
1. Inverse
Equilibrium
● System is at equilibrium when rate of forward reaction is equal to the
rate of backward reaction
● Concentrations of reactants + products remain unchanged at
equilibrium
● Reversible reaction = products can reform to produce reactants
● Only occurs in a closed system (only energy but not matter can be
exchanged)
Dynamic equilibrium
● Rate of forward + backward reaction is equal
● No changes at macroscopic level
● Changes in microscopic level
Equilibrium state
1. Dynamic: Reaction hasn't stopped, forwards + backwards reaction
occur at same rate
2. Closed system: No exchange of matter, reactants + products can
recombine
3. Constant concentration of reactants/products: Produced + destroyed
at an equal rate
, 4. No macroscopic changes: Because they depend on concentration of
reactants and products
5. Equilibrium can be reached from either direction
Equilibrium constant (Kc)
● Kc = [Products]^Coefficient stoichiometry/ [Reactants]^Coefficient
stoichiometry
● Kc has a fixed value at a specific temperature
Magnitude of Kc
● Kc > 1 = More products
- [Products] > [Reactants]
● Kc < 1 = More reactants
- [Reactants] > [Products]
● Kc = 1
- [Products] = [Reactants]
- Half-point has been reached
Reaction quotient (Q)
● Q = Equilibrium expression with non-equilibrium concentration of
[Products] and [Reactants]
● Can be used to measure whether reaction is at equilibrium
- Q = Kc → Equilibrium
- Q > Kc → Q decreases as the reaction moves toward equilibrium →
[Reactants] should increase, [Products] should decrease → Reaction
shifts to the left
● Q < Kc → Q increases as the reaction moves towards equilibrium →
[Reactants] should decrease, [Products] should increase → Reaction
shifts to the right
Kc relationships with different reactions
1. Inverse
