Equilibrium Flashcards
what does irreversible mean
when the reaction proceeds in one direction only, goes to completion, and the maximum amount of product formed is determined by the amount of limiting reagent initially present
what does reversible mean
when the reaction can proceed in either direction, usually doesn’t not go to completion and usually goes into dynamic equilibrium (when the system’s entropy is at a maximum and gibbs free energy is at a minimum)
what is the law of mass action
states that if the system is at equilibrium at a constant temperature, then the following ration is constant
Keq= [C]^c[D]^d/[A]^a[B]^b
what is the reaction quotient, Q
essentially serves as a timer to indicate how far the reaction has proceeded toward equilibrium
Qc = [C]^c[D]^d/[A]^a[B]^b
what does it mean when Q < Keq
the forward reaction has not yet reached equilibrium
there is a greater concentration of reactants
the forward rate of reaction is increased to restore equilibrium
what does it mean when Q = Keq
the reaction is in dynamic equilibrium
the reactants and products are present in equilibrium proportions
the forward and reverse rates of reaction are equal
what does in mean when Q > Keq
the forward reaction has exceeded equilibrium
there is a higher concentration of products
the reverse rate of reaction is increased to restore equilibrium
Keq is a characteristic of particular reaction at a given temperature; therefore the equilibrium constant is
temperature-dependent
the larger the value of Keq …
the farther to the right the equilibrium position
if the concentration of products is greater than the concentration of reactants, Keq must be
greater than 1 or Keq > 1
if the concentration of reactants is greater than the concentration of the products, Keq must be
less than 1 of Keq < 1
what does a large positive exponent in Keq mean
the reaction strongly favors products at equilibrium
the larger the exponent, the less reactant that will be present at equilibrium
the reaction goes almost to completion
what does a large negative exponent in Keq mean
the reaction strongly favors reactants at equilibrium
What does Le Chatelier’s Principle state
that if a stress is put on a system, the system shifts to relieve that applied stress
if reactants are added/products are removed to a reaction in equilibrium, what direction will the reaction proceed
this means Qc < Keq
this means that the reaction will spontaneously proceed in the forward direction
if reactants are removed/products are added to a reaction in equilibrium, what direction will the reaction proceed
this means that Qc > Keq
this means that the reaction will spontaneously proceed in the reverse direction
what kind of chemical reactions will be affected by changes and pressure and volume
reactions with at least 1 gaseous species
if a system is compressed, what direction will the reaction proceed
if the system is compressed, this means that the pressure has increased
the reactions will move toward the side of the reactions that has fewer moles of gas
if a system expands, what direction will the reaction proceed
if the system expands, that means the pressure has decreased
the reaction will move towards the side of the reaction that has more moles of gas
what does a change in temperature change: the Keq or the Q
the Keq is changed
the change in temperature does not cause the partial pressures or the concentrations to change immediately
if the reaction is endothermic (H>0) heat functions as
a reactant
if the reaction is exothermic (H<0) heat functions as
a product
if heat is added and the temperature increases, the reactions shifts to the
right
if heat is removed and the temperature decreases, the reactions shift to the
left
