Chemical Equilibrium Flashcards
when two opposing reactions occur simultaneously at the same rate, what is achieved?
chemical equilibrium
this occurs when the rate of forward rxn is equal to the rate of reverse rxn
equilibrium
formula for chemical equilibrium assuming A→B
Keq = Kf/Kr
or
[B]/[A]
Forward rate constant over Reverse rate constant/products over reactants
Keq is often associated with Kc or K; When Kp, it is used for partial pressure (or pressure only) and rxn must be homogenous w/o pure solids
If 1N2(g) + 3H2(g) ⇄ 2NH3(g) is given, what is Kc and Kp?
Kc = [NH3]2/[N2] [H2]3
Kp = P[NH3]2/P[N2] P[H2]3
If 1N2(g) + 3H2(g) ⇄ 2NH3(g) is given, what is Kp if Kc is 9.60 at 300oC
use formula Kp = Kc (RT)Δn
wherein: R = gas constant 0.0821 Latm/molK
T = absolute temp (+273.15)
Δn = product - reactant coefficients
Therefore
Kp = 9.60 ((0.0821)(300+273.15))2-4
Kp = 4.34 x 10-3
hehe i added para lng makita use ng formula
If 1N2(g) + 3H2(g) ⇄ 2NH3(g) is given, what is Kc if Kp is 1.45 x 10-3 at 500oC
use formula Kp = Kc (RT)Δn
wherein: R = gas constant 0.0821 Latm/molK
T = absolute temp (+273.15)
Δn = product - reactant coefficients
Therefore
Kc = Kp/(RT)Δn
Kc = 1.45 x 10-3/((0.0821)(500+273.15))2-4
Kc = 5.84
hehe i added para lng makita use ng formula
If K > 1, which side is preferred in a reaction?
products dominate and is favored. equi is to the right
if K and 1, look at tail. If Q and K, tingin sa bunganga
If K < 1, which side is favored?
reactant side is favored; equilibrium is to the left
if K and 1, look at tail nito (<). If Q and K, tingin sa bunganga (<)
what do you call the equilibrium wherein reactants and products are in different phases?
heterogenous equilibrium
what do u call the equilibrium wherein products and reactants are in the same phases?
homogenous equilibrium
what do u call this equilibrium that has many steps?
multiple equilibrium
when looking for K, multiply equi constants for each step
If K = equilibrium constant, what is Q for?
Q = initial concentration of products over reactants
same as K pero this one deals w/ the initialzzxzc
what can u say if Q = K
prod-favored, reactant-favored, or at equi
system is at equilibrium
what is favored when Q < K?
forward rxn is favored; product-favored
if K and 1, look at tail. If Q and K, tingin sa bunganga
what is favored when Q > K?
reverse rxn is favored; reactant-favored
if K and 1, look at tail. If Q and K, tingin sa bunganga
what do u call the principle wherein it states that if stress is applied to a system in equilibrium, the system will adjust in such a way that the stress is partially offset to achieve a new equilibrium?
basically, the system will try to achieve equilibrium if may imbalance
Le Chatelier’s principle
determine if forward rxn or reverse rxn is favored
↑ in conc of products
reverse rxn
determine if forward rxn or reverse rxn is favored
↑ in conc of reactants
forward rxn
determine if forward rxn or reverse rxn is favored
↓ conc of reactants
reverse rxn
determine if forward rxn or reverse rxn is favored
↓ conc of products
forward rxn
what does it mean if a rxn has a positive enthalpy?
it means it is endothermic in nature
it increases in temp as rxn goes on (assuming forward onli)
what does it mean when a rxn has a negative enthalpy?
it means it is exothermic
decreases temp as rxn goes on (assuming forward rxn)
determine if forward rxn or reverse rxn is favored
in an endothermic rxn, what happens if u increase temp?
forward rxn is favored
tip: look wer the endothermic side is, usually ↑ in temp is on dat side
similarly, the decrease in temperature is found sa exothermic side ng rxn (product or reactant)
determine if forward rxn or reverse rxn is favored
↓ temp in endothermic rxn
reverse rxn is favored
determine if forward rxn or reverse rxn is favored ↑↓
↑ temp in exothermic
reverse side is favored
determine if forward rxn or reverse rxn is favored ↑↓
↓ temp in exothermic
forward rxn is favored
determine if forward rxn or reverse rxn is favored ↑↓
↑P (only applicable to gases)
favors side w/ fewer gas molecules
↑P ↓V
determine if forward rxn or reverse rxn is favored ↑↓
↓P in gases
favors side w/ more gas molecules
↓P ↑V
A catalyst affects the equilibrium and speeds up reactions, allowing system to reach equilibrium.
True or False?
False. A catalyst does not affect equi, but indeed it speeds up rxns (so it affects rxn rates but not equi)
