ch 6 Flashcards
equilibrium
when the forward reaction rate = the backward reaction rate
@ equilibrium, the amount of react and product remain constant
equilibrium expression
kc = [products]^n / [reactants]^n
pressure equilibrium expression
kp = (Pproducts)^n/(Preactants)^n
reaction between Kc and Kp
Kp=Kc(RT)^delta n
delta n = products moles — reactants moles
what does a k»1 mean
reaction is product-favored
add to product side
what does K«1 mean
reaction is reactant-favored
add to reactant side
solving for equilibrium concentration values (step-by-step)
use an ice chart
- add to side with initial value 0 OR look at K-value to see shift in equilibrium
- use x=(-b+- sqrt (b^2) - 4ac )/2a to solve for x
Manipulating K
K-value when original equation is multiplied by a #
Ex:
N2O4 <—> 2NO2. K=0.212
2N2O4<—> 4NO2. K=???
raise K to the Number you multiplied by
K=(0.212)^2
Manipulating K
What is K value when you have a reverse reaction of the original reaction
Ex:
N2O4 <—> 2NO2. K=0.212
2NO2 <—> N2O4. K=???
K= 1/0.212
put K under 1
Manipulating K
two equations added together to form a third reaction —> what is K value
K3 = (K1)(K2)
multiply k values of first two equations
exothermic
also what happens to K when u increase heat
releases heat as a product
reactant —> product + heat
if you increase heat you decrease K
reaction shifts to left
Endothermic
what happens when you increase heat
absorbs heat as a reactant
reactant + heat —> product
increase heat = increase K
shift to right
what is the reaction quotient
Q
indicated reaction concentration ratio at any point in reaction
comparison to K tells us which way the reaction needs to shift until equilibrium is reached
Q=K
reaction is at equilibrium
Q<K
reaction will shift to the right until equilibrium is reached
Q>K
reaction will shift to the left until equilibrium is reached
Le Chateliers Principle
when a stress is added to a reaction at equilibrium, it will shift to a certain direction until equilibrium is reached again
what happens when u remove a gaseous product in a reaction at equilibrium
reaction shifts to the right
(Q<K)
what happens when you add a gaseous product that is at equilibrium
reaction shifts to left
(Q>K)
what happens when you add HCl to the following reaction:
Mg(OH)2 (s) <-> Mg^2+ + OH-
shifts to the right because H+ forms water with OH- so you are basically removing product
volume and pressure relationship
inverse relationship
when you reduce volume pressure increases
when you increase volume pressure decreases
what happens when you reduce volume
reaction shifts to side with less moles of gas (pressure is high so it wants to go to side with less pressure)
what happens to reaction when mol reactant= mol products and there is a change in volume
nothing
no shift
