40S Unit 3: Chemical Equilibrium I Flashcards
what are the 2 types of equilibrium
dynamic and static
what is a static equilibrium
a motionless equilibrium involving the balance of stationary objects
what is a dynamic equilibrium
an equilibrium that involves the balance of opposing motions in which the rate of the forward reaction is equal to the rate of the reverse reaction
what are the 3 types of dynamic equilibriums
solubility, phase and chemical
what is a closed system
a system that may exchange energy but not matter with its surroundings
what do dynamic equilibriums always have
they always involve 2 opposing reaction rates that are equal in size yet opposite in flow
do the amounts of species on each side of a reaction have to be equal in dynamic equilibriums?
no, they do not need to be equal in concentration or amount
what is a solubility equilibrium and give an example
they involve solutions where the rate of dissolving and the rate of precipitation are equal.
e.g.:
NaCl(s) in equilibrium with Na+(aq) + Cl-(aq)
what is a phase equilibrium and give an example
equilibrium between opposing phase change rates where the chemical reactant and product are the same but the phase changes and can occur between any phases
e.g.:
H2O(l) in equilibrium with H2O(g)
what is a chemical equilibrium and give an example
equilibrium between the forward rate of reaction and the reverse rate of reaction
e.g.:
2H2(g) + O2(g) in equilibrium with 2H2O(g)
when does equilibrium occur on a graph
whenever the concentration of reactants and products plateau
what is percent reaction and what is the formula
an indication of how completely the reactants have formed products
% reaction = (actual yield / theoretical max yield) x 100%
the theoretical max yield is the yield provided by the stoichiometry
if a reaction is 99% complete, what is it called
a quantitative reaction (considered to be a one way reaction)
what are the 4 ways we can express equilibrium
- graphs/pictures
- words
- numbers
- ICE chart
what does ICE stand for
I - initial concentration
C - change in concentration
E - equilibrium concentration
what is the formula for moles (n), concentration (C) and volume (V)
n = C x V
if a reaction is a quantitative reaction, what is its % reaction
99%
if a reaction is product favoured, what is its % reaction
50% < x < 99%
if a reaction is neither favored, what is its % reaction
50%
if a reaction is reactant favoured, what is it’s % reaction
1% < x < 50%
if there is no reaction, what is it’s % reaction
1% or less
if there is ________________________________________ we have an equilibrium
more than 1% reverse reaction
if one reactant changes _________, all other reactants must change negatively but all products change ________
negatively, positively
state if this is product favoured, reactant favoured or neither
reactants changes negatively and products change positively
product favoured
state if this is product favoured, reactant favoured or neither
no changes
neither favoured
state if this is product favoured, reactant favoured or neither
reactants change positively and products change negatively
mostly reactant favoured
who determined the formula for the equilibrium constant
Guldberg and Waage in the 1800s
they realized that no matter how a reaction starts and ends, something stays the same
given the reaction
aA + bB in equilibrium with cC + dD
what is the equilibrium constant equation
k = [D]^d • [C]^c / [A]^a • [B]^b
k is measured in M
only using equilibrium concentrations not initial
what is the difference between the rate law and the equilibrium constant
the rate law doesnt use coefficients as the exponents, it uses the reaction rate, but the equilibrium constant uses the coefficients
how do you differentiate between the equilibrium constant for the regular reaction and the reverse reaction
regular —> k = products / reactants
reverse —> k’ = reactants/ products
when is the equilibrium constant true
when the temperature and pressure are constant as k stays constant regardless of initial concentration
what is a limitation of k
changing anything other than concentration as it will result in a different k
when does concentration change, when i add more solid, liquid or gas
when i add more gas and/or aqueous solutions
when does concentration change, when i add more solid, liquid or gas
when i add more gas and/or aqueous solutions
what appears on ICE charts, solids, liquids, gases or aqueous solutions
gases and aqueous only
determine which is product favoured, which is neither and which is reactant favored
k < 1, k > 1, k = 1
k < 1 is reactant favoured
k > 1 is product favored
k = 1 is neither favored
what is Le Chatelier’s principle
when a chemical system in equilibrium is disturbed by a change in a property, the system responds to oppose that change
as the system changes to oppose the disturbance, ________ species in the equilibrium changes
every
what are 3 ways to disturb a system
- change concentration
- change temperature
- change pressure
if a reaction is exothermic, what side is heat added to the reaction
the products side because heat is released
in an exothermic reaction, is H negative or positive
negative
where is heat added in an endothermic reaction
to the reactants side
in an endothermic reaction, is H negative or positive
positive
the amount of concentration changes depending on the __________________
stoichiometry
what type of equilibriums do pressure disturbances affect
equilibrium systems containing at least one species that is a gas
if we increase the pressure on an equilibrium, how will the system respond
the system will respond to decrease the pressure by flowing to the side with less moles of gas
if we decrease the pressure on an equilibrium, how will the system respond
the system will respond to increase the pressure by flowing to the side with more moles of gas
