Equilibrium Flashcards
Reactions can go both ways. These reactions are called ________ if its easily observed both ways
Reversible
Proceeds to complete OR irreversible means:
the reverse reaction is too slow to detect, only trace reactants remain (still in dynamic equilibrium)
Chemical equilibrium
State when concentrations of reactants and products reman constant over time (things stop changing)
On a graph what should chemical equilibrium look like
the lines are like parellel and straight like a equals (=) sign
At equilibrium, the ________ and ________ reactions occur at the ______ rate
forward, reverse, same
At equilibrium the ___________ are still ocurring, but there isn’t ____ ___ ___________
Reactions, NO NET REACTION
Chemical equilibria are ______ and ________
dynamic and reversible
aA + bB <–> cC dD equilibrium equation in a formula is what??
products on top reactants on bottom, a goes exponent A etc
Reversing the reaction is just
inverse it OR
K(rev) = 1/k(forward)
multiplying the reaction is just
Kc (double) =Kc²
or whatever it is multiplied by, put it as an exponent of original kC
adding reactions you can ______ ____ common multiples (reaction intermediates)
cancel out
,Equilibrium constants are defined as _______ ______ and why?
Unitless quantities and cuz its DEFINED by the activity which is just moles divided by moles
Homogenous equilibria
only chemical change
Heterogeneous equilibria
Chemical change AND phase change
Pure _____ + _______ are ________ from equilibrium expressions because they are always in their ______ _____
Solids
liquids
excluded
standard state
ensure K is unitless, each MUST be unitless
for a species in solution:
for a gas:
species: ax= [X]/[X]ref (1.0M)
For a gas:
ax = P/Pref 1.0atm
ax = 1.0
For gases u can use _____ instead of _______
pressures
concentrations
Working with gas formula
Kₚ = Kc (RT)Δⁿ
R is gas constant 0.08206
T is kelvin
Δn is number of moles of GASEOUS products minus GASEOUS reactants NOT THE DIFFERENCEEEEEE
IF Kc > 10³
reaction proceeds _____ __ _______, products favoured
nearly to completion
IF Kc < 10⁻³
Reaction proceeds ______ __ _____, reactants favoured
hardly at all
10⁻³ < Kc < 10³
Appreciable _________ of both _____ and ______
concentrations
reactants
products
Use quadratic equation when
u have the x stuff in a kc
Chataliers principle
If stress is applied to a reaction mixture AT equilibrium, a net reaction occurs in the direction that relieves the stress.
Examples of chatalier stresses than can be applied (3)
concentration of reactant or product
Pressure (and/or) volume
Temperature
On a concentration graph, chatalier principle will show a spike of added _____, a ______ in the other reactant getting ___ __, and an _______ in the product
reactant
decrease
used up
increase
For chatalier change in concentration, use hands as added or taken out and see
do it
For chatalier change in volume/pressure, REDUCING volume will _______ partial pressures and ______ total moles of gas
increase
reduce
For chatalier change in volume/pressure, INCREASING volume will _______ partial pressures and ______ total moles of gas
decrease
increase
other ways of changing pressure:
adding inert will ____
Adding reactant/product gas
do nothing cuz partial pressures dont change
Increases THAT gas’s partial pressure
For adding temp, use hands in reactant or product
DO IT
sign for Kc for an exothermic reaction
negative , DECREASES as the temperature INCREASES
DECREASE INCREASE
sign for Kc for an endothermic reaction
positive , INCREASES as temp INCREASES
For temperature Kc diagram with balls, how to tell if its endo or exo thermic
follow if kC INCREASE as temp INCREASE (endothermic) or if kC decrease as temp INCREASE (exo)
How to link chemical equilibrium and kinetics:
IF Kc is really large
IF Kc is nearly unity
IF kc is really small
large: Kfwd»_space;Krev and rxn goes almost to completion
unity: Kfwd ~= Krev, products and reactants exist in equilibrium
small: Krev»_space; Kfwd, consits mostly of reactants
How would the rates and equilibrium constants be connected in a multi-step (overall) reaction?
rules of sequential equilibria
Ktotal = K1K2 = (Kf1/Kr1) * (Kf2/Kr2)
Exothermic graph will have higher or lower products? WHat is the Ea?
Lower (releasing energy)
Ea arrow + released energy arrow
Endothermic graph will have higher or lower products? WHat is the Ea?
Higher product (absorbing energy)
Ea arrow BESIDE the shorter energy absorbed arrow
What is Kc
equilibrium constant
Is Kc affected by catalyst? explain
NO
catalyst speeds up forward or reverse by SAME factor, so equilibrium misture is unchanged
reaction quotient
products over reactants
K = at equilibrium
Q = current concentration
they both use the same forumla.
What is when K > Q
What is when K < Q
What is when K = Q
too few product, shift right
too much product, shift left
equilibrium, no shift
