Equilibrium Flashcards
What is equal when a reaction is at equilibrium
Forward and reverse reactions
I’m equilibrium the reaction is not
Static
In equilibrium, the rates of forward and reverse reactions are
Equal
At equilibrium, the concentration of products and reactants
Remain constant
Chemical equilibrium
Equilibrium involving a chemical reaction
Physical equilibrium
Equilibrium involving physical change (states of matter)
Chemical equilibrium has two types :
Homogenous and heterogenous
Homogenous equilibrium
All chemicals are in the same state of matter
Heterogenous equilibrium
More than one state of matter
The equilibrium constant
No matter starting composition of reactants and products, the same ratio of concentrations is achieved at equilibrium
The equipment constant expression
Kc= produces over reactants
[P][P]/[R][R]
Kc is
Equilibrium constant
Based on molarities
The larger the K value
The more products present at equilibrium
K»1
Products dominate at equilibrium (equilibrium to left) right shift
K«1
Reactants dominate at equilibrium (equilibrium to right) left shift
LeChateliers principle
If you disturb equilibrium, it will shift to undo disturbance,
(Changing in products or reactants concentrations)
Adding a reactant or product
Shifts the equilibrium away from the increase
Removing the reactant or product
Shifts the equilibrium towards the decrease
To optimize the amount of product at equilibrium
Flood reaction vessel with reactant and continually remove products
Increase of pressure
Favors the direction that has fewer moles of gas in a reaction
Decrease in pressure
Shift toward larger number of gas moles
Temperature increase or decrease
Using energy term in equation, can be treated like reactant or product
Does changing temperature change the value of K (ratio)
Yes
Positive Kj
Reactant
Endothermic
Negative Kj
Product
Exothermic
What do solids do for equilibrium
Adding or removing solids does not shift equilibrium
Adding or removing catalyst
Doesn’t shift
Only speeds up reaction
Increasing volume
Decreases reactants and products
What increases the rate of a reaction and why
Breaking it up increases surface area so more collisions
Higher concentration so more in it so more collisions
Dynamic equilibrium
There is constant change but the total remains the same
When shifts to right (happens to reactants)
It favors products, so need to decrease reactants
If a system at equilibrium is subjected to a disturbance
The equilibrium is displaced in the direction that relieves the disturbance
Stressor
Any change which could affect equilibrium of either or both forward or reverse reactions
Forward reaction is faster
What happens to shift
Products
Reactants
Shift right
Increase products
Decrease reactants
When added
Shifts away
When removed
Shifts toward
Characteristics of equilibrium
Concentration
Pressure
When approaching equilibrium reactant concentration
Decreases because used to make products
When approaching equilibrium product concentration
Increase because formed in forward reaction
When approaching equilibrium forward reaction rate
Decrease
Lower reactant concentration= less collisions
When approaching equilibrium reverse reaction rate
Increase
Higher product concentration= more collisions
What is constant at equilibrium
Concentration
Law of mass action
The ratio of forward and reverse reactions is described by the equilibrium constant kc
ICE
I- initial concentrations
C-change, -(coefficient)x
E- concentrations at equilibrium
