Chapter 13 Flashcards
static equilibrium does not occur in?
chemical systems
chemical equilibrium
usually studied in a closed system with controlled variables.
Equilibrium
the state where the concentrations of reactants and products remain constant over a period of time
all reactions that are carried out in a closed system will?
reach equilibrium at some point.
If little product is formed the equilibrium is?
far to the left or reactant favored
If little reactant remains the equilibrium is?
far to the right or product favored
In static equilibrium, reactions?
do not take place
In dynamic equilibrium, reactions?
continue to take place
In static equilibrium, products?
will remain products
In dynamic equilibrium, products?
continue to be converted to reactants
In dynamic equilibrium, when products continue to be converted to reactants what is that called?
reverse reaction
In static equilibrium all unused reactant molecules will?
remain unreacted
In dynamic equilibrium reactant molecules continue?
being converted into products
Causes of equilibrium?
beginning of reaction, middle of reaction, at equilibrium
Equilibrium at beginning reaction
only reactant molecules exist, so only reactant molecules may collide
Equilibrium in the middle of reaction
as product concentration increases, collisions may take place that lead to the reverse reaction.
equilibrium at equilibrium
rates of forward and reverse reaction are identical
k is a constant called?
the equilibrium constant
k varies depending on?
temperature and value of the coefficients of the balanced equation
equilibrium position
a set of specific conditions that define when the system has reached the equilibrium point
In the equilibrium position k can only have ?
one value at a specific temperature
k can only have ___ value but_____?
one, the system can have an infinite number of equilibrium positions
Why can a system have an infinite number of equilibrium positions?
the specific equilibrium position is dependent on the initial concentrations of the species in the reaction.
When the balanced equation for a reaction is multiplied by some factor, the equilibrium position for?
the new reaction is the original expression raised to the nth power
For a particular reaction at a given temperature, the value of k is?
constant regardless of the amount of gases that are mixed together.
the position of heterogeneous equilibrium does not?
depend on the amounts of pure solids or liquids present because their concentrations remain constant
In a heterogeneous equilibrium, if pure solids or gases are present we?
omit them from our law of mass action equation
In a heterogeneous equilibrium, only gases and aqueous solution are?
included in mass action laws when working with heterogeneous reactions
reactions with large equilibrium constants
k > 1
when k > 1 the reaction is likely to?
be completed and equilibrium position is far to right.
large equilibrium constants generally have?
large and negative Δ E
reactions with small equilibrium constants
k < 1
when k < 1 the reaction is likely to?
not take place, consist of mainly reactants, and equilibrium position is far to left.
time required to reach equilibrium is related to?
the reaction rate and activation energy
time required to reach equilibrium is not related to?
the magnitude of k
to find Q, we use?
the initial concentrations and not the equilibrium concentrations.
If Q = K the system is at?
equilibrium and no shift occurs
If we apply the law of mass action to our initial concentrations, than we can?
determine what direction the reaction must move in order to achieve equilibrium
If Q > K the system will?
shift to the left, consuming products and forming reactants to reach equilibrium
If Q < K the system will?
shift to the right, consuming reactants and forming products to reach equilibrium.
Le Chatlier Principle
States that any equilibrium reaction will do what is necessary to return to equilibrium if we change a condition.
Equilibrium systems want to remain?
constant
For Le Chatlier Principle, systems must be?
closed so that the adjustment occurs
If we increase the concentration of any compound of an equilibrium system, the system will shift?
away from the change in opposite direction
The opposite shift that takes place during an increase in concentration will?
consume anything that is on the same side as what we increased
The opposite shift that takes place during an decrease in concentration will?
consume anything that is on the same side as what we decreased
Ways to change pressure
-add or remove a gaseous reactant or product
-add an inert gas
-change the volume of the container
inert gases _____ the pressure but have no effect on ______ or ________.
increase, concentrations, partial pressures
If pressure is increased on a system, the equilibrium will shift?
to the side with less moles of gas
If pressure is decreased on a system, the equilibrium will shift?
to the side with more moles of gas to maintain energy
When volume is reduced the shift is?
high # of moles to low # of moles
When volume is increased the shift is?
low # of moles to high # of moles
in endothermic systems heat is a?
reactant
in endothermic reactions if we increase temp/heat/energy the shift is?
to the right
in endothermic reactions if we decrease temp/heat/energy the shift is?
to the left
endothermic reactions have __ Delta h
positive
in exothermic systems heat is a?
product
in exothermic reactions if we increase temp/heat/energy the shift is?
to the left
in endothermic reactions if we decrease temp/heat/energy the shift is?
to the right
exothermic reactions have __ Delta h
negative
add a reactant shift to?
products
add a product shift to?
reactants
increase temperature
shift away from heat
decrease temperature
shift towards heart
increase pressure
shift to side with fewer moles of gas
decrease pressure
shift to side with more moles of gas
the only stress that changes Keq is?
temperature
