equilibrium Flashcards
open system
exchanges energy & matter with surroundings
closed system
exchanges only energy with surroundings
reversible reaction
products once formed can react & re-form reactants
“⇌”
products can collide with enough energy [reverse activation energy] to cause the reverse reaction
dynamic equilibrium
both reactants & products are present
rate of forward reaction = rate of reverse reaction
bonds constantly broken & formed
can only occur in a closed system
le chatelier’s principle
if a stress is applied to a system at equilibrium, the system will oppose the stress & restore equilibrium
temperature’s effect on equilibrium
permanent effect on position of equilibrium & equilibrium constant
exothermic reaction
reaction that releases energy
negative enthalpy change
energy among products
endothermic reaction
reaction that absorbs energy
positive enthalpy change
energy among reactants
temperature’s collision theory
↑temperature = ↑kinetic energy (reactants & products)
reactants & products move faster
↑frequency of collisions; thus, successful collisions
↑rate of reaction
decrease temperature [endothermic reaction]
system opposes the stress by favoring the reverse reaction
exothermic reaction releases heat
reaction moves to the left-hand-side
reactants are favored
equilibrium constant decreases
increase temperature [endothermic reaction]
system opposes the stress by favoring the forward reaction
endothermic reaction absorbs heat
reaction moves to the right-hand-side
products are favored
equilibrium constant increases
decrease temperature [exothermic reaction]
system opposes the stress by favoring the forward reaction
exothermic reaction releases heat
reaction moves to the right-hand-side
products are favored
equilibrium constant increases
increase temperature [exothermic reaction]
system opposes the stress by favoring the reverse reaction
endothermic reaction absorbs heat
reaction moves to the left-hand-side
reactants are favored
equilibrium constant decreases
pressure’s effect on equilibrium
no effect on equilibrium constant, only position of equilibrium
pressure’s collision theory
↑pressure packs gas molecules closer together
↑frequency of collisions; thus, successful collisions
↑rate of reaction
increase pressure
favors the side of least molecules
decrease pressure
favors the side of most molecules
concentration’s effect on equilibrium
no effect on equilibrium constant, only position of equilibrium
catalyst’s effect on equilibrium
no effect on equilibrium constant nor position of equilibrium
↓activation energy (forward & reverse reaction)
↑rate of reaction (forward & reverse reaction)
↓time taken to reach equilibrium
extent of reaction
how much product is formed at equilibrium
equilibrium constant
expresses the relationship between reactants & products at equilibrium
(g) & (aq)
(s) & (l) do not appear in the Kc expression (unless all species in the system are liquid)
H₂O appears in the Kc expression if it is a reactant or product
Kc > 1
products favored
Kc = 1
reactants & products balanced
Kc < 1
reactants favored
reaction quotient
expresses the relationship between reactants & products at any position
relative to equilibrium
Q > Kc
reactants favored
Q < Kc
products favored
