TOPIC 9- CHEMICAL EQUILIBRIUM Flashcards
applies to the extent of a reaction, the
concentration of product that has appeared after an unlimited
time, or once no further change occurs.
Equilibrium
is the state where the concentrations
of all reactants and products remain constant with time.
Chemical Equilibrium
At equilibrium,
rate forward = rate reverse
is the ratio of reactants and products
calculated the same way as Keq.
Reaction quotient
If Q = K, the reaction is in
equilibrium
If Q < K, the reaction will proceed from
reactants to products
If Q > K, the reaction will proceed from
product to reactants
applies to reactions in which all reacting species are in the same phase.
Homogeneous Equilibrium
Only _________________ are accounted for in calculating the
reaction quotient and the equilibrium constant.
Gaseous species
three ways to change the pressure of a reaction system
involving gaseous components.
- Add or remove a gaseous reactant or product.
- Add an inert gas (one not involved in the reaction).
- Change the volume of the container.
Adding a gaseous reactant increases the volume of the reactant
side. For the system to reach equilibrium again, the volume is
decreased by
increasing pressure
Increasing the pressure (decreasing the volume) shifts the
equilibrium to form
fewer molecules and moles of gas
Decreasing the pressure (increasing the volume) shifts the
equilibrium to form
more molecules and moles of gas
If a gaseous reactant/product is added/removed, check the
changes in Q to determine where the
equilibrium shifts
The addition of an inert gas increases the ________________ but
has no effect on the concentrations
total pressure
When the volume of the container is changed,
concentrations (and thus the partial pressures) of both
reactants and products are changed.
Reducing the volume of the container shifts the equilibrium to the
side with ____________________ in the balanced equation.
fewer gas molecules
Increasing the volume of the container shifts the equilibrium to the
side with ______________ in the balanced equation.
more gas molecules
ndicates there are relatively large
concentrations of product gases as compared with the
concentrations of reactant gases at equilibrium.
large value for Keq (Keq > 1)
A reaction with
a large Keq value is a
good source of products
Keq and Kp are equilibrium constants as determined by the
law of mass action
Q is called the
reaction quotient
Q has the same
form as Keq or Kp, but instead of equilibrium concentration, ___________ are used to calculate the Q value.
initial concentrations
When a chemical system at equilibrium is subjected to stress,
the system will return to equilibrium by shifting to reduce the
stress.
Le Chatelier’s Principle
If the reactant concentration increases, the system reacts to
consume some of it
if the concentration decreases, the system
reacts to
produce some of it
If the concentration of the product decreases, the system
reacts to
produce some of it
The reaction will start from which side concentrations were
increased
Only _________changes can alter K.
temperature
is considered as a product or reactant
heat
In exothermic reactin, heat is a
product
in endothermic reaction, heat is a
reactant
applies to reactions in which reactants and products are in different phases.
Heterogeneous equilibrium
