Quiz 1 Flashcards
What happens and what direction does a rxn at equilibrium go when you add reactants?
To the right and produces more products
What happens and what direction does a rxn at equilibrium go when you remove reactants?
To the left and produces more reactants
What happens and what direction does a rxn at equilibrium go when you add products?
To the left and produces more reactants
What happens and what direction does a rxn at equilibrium go when you remove products?
To the right and produces more products
Heating an exothermic reaction
Equilibrium shifts towards the reactants and K decreases
Heating an endothermic reaction
Equilibrium shifts towards the products and K increases
Q<K
Shifts right and produces products (reactants consumed)
Q>K
Shift left and consumes products (produces reactants)
Small K
Left, reactants increase and products decrease
Large K
Right, reactants decrease and products increase
Cooling an exothermic reaction
Moves to the right and produces more products and K increases
Cooling an endothermic reaction
Moves to the left and produces more reactants and K decreases
Le Chatelier’s Principle
Added stress @equilibrium = shifts in direction to reduce change
Q=K
equilibrium and no change
Equilibrium
A rxn will continue going in the forward and reverse direction because concentration and pressure are no longer changing
Equilibrium constant
Relationship between products and reactants at equilibrium (P/R)
Equilibrium position
Concentration of each molecule at equilibrium based on initial concentration
There are an _____ number of initial concentration and equilibrium positions
Infinite
What does the equilibrium constant depend on?
Temperature
What does the equilibrium position depend on?
Temperature, pressure, and/or initial concentrations
What is the equilibrium constant (K) for a reverse reaction?
K’ = 1/K
What is the equilibrium constant (K) if the rxn is multiplied by a factor n?
K” = K^n
Kc = Kp(RT)^?
-Δn
Kp = Kc(RT)^?
+Δn
What is Δn?
Difference in mols (P-R) of gaseous species only
How does the rate of a forward reaction change as the rxn approaches equilibrium?
Rate decrease b/c reactant concentrations are decreasing
K>1
Large K and mainly products
K<1
Small K and mainly reactants
Do rates depend on time required to reach equilibrium?
No, only temperature
How is Q different than K?
Q is the concentrations at any time, K is the concentrations at equilibrium
Do catalysts influence rate or position of equilibrium?
Rate
What is a catlyst?
Substance that speeds up a chemical rxn or lowers temp/pressure to do so
Decrease volume =
Increase in partial pressure and decrease in moles of gas
Increase volume =
Decrease in partial pressure and increase in moles of gas
Where does equilibrium shift when pressure is increased?
Toward side with fewer moles of gas
Where does equilibrium shift when pressure is decreased?
Toward side with more moles of gas
What is Q called?
Reaction quotient
What is used to calculate Q?
Initial concentrations/concentrations not at equilibrium
